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Surgical Resolution of Soft Tissue Disorders
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Table of Contents
- Patient Evaluation
- Patient Preparation
- Wound Healing
- Laser Surgery
- Illumination and Magnification
- Suture Materials and Adhesives
- Postoperative Care
- Rhinolith Removal
- Infraorbital Exploration and Trephination
- Choanal Atresia
- Rupture of the Cervicocephalic Air Sac
- Oral Cavity
- Esophageal Perforation
- Crop Burn Repair
- Ingluviotomy and Crop Biopsy
- Esophageal Stricture Correction
- Anatomy of the Female Reproductive Tract
- Ovocentesis and Manual Egg Delivery
- Caesarean Section/oviductalsparing Celiotomy
- Removal of the Ovary and Ovarian Biopsy
- Anatomy of the Male Reproductive System
- Orchidectomy and Testicular Biopsy
Preparation and Considerations for Avian Surgery
A full signalment and history should be obtained and a physical examination performed prior to anesthesia and surgery (see Chapter 6, Maximizing Information from the Physical Examination and Chapter 34, Surgical Resolution of Orthopedic Disorders).
Preoperative diagnostics may include a complete blood count, serum chemistry and electrolyte profile, and other serologic or hematologic tests. The surgeon should evaluate the risk/benefit ratio for each diagnostic test, particularly in smaller avian patients (<100 g). Presurgical blood collection may cause hypovolemia and/or anemia that may dispose these birds to life-threatening intraoperative hemorrhage. Hematologic findings that may preclude or delay elective surgery are similar to those in domestic animals. These include the following:
- An elevated hematocrit, which may indicate dehydration or cardiovascular compromise.
- A decreased hematocrit. Anemic patients have increased surgical risks, particularly if there is perioperative hemorrhage . Severe anemia (i.e., PCV <20%) requires correction or treatment prior to surgery.
- A decreased total protein, which may delay healing as well as indicate underlying metabolic disease.
- Leukocytosis, which may indicate an infectious or inflammatory process, requiring pre-, peri- and postoperative antimicrobial therapy. Perioperative antibiotic or antifungal agents should be administered when indicated.
- Hypocalcemia that may pose an anesthetic risk, compromise cardiac and neurologic function, and impair bone healing subsequent to fracture repair . Evaluation of both total calcium and ionized calcium is strongly recommended prior to surgery  (M. Stanford, personal communication, 2000), particularly in those patients with associated malnutrition or history of egg production.
- Organ system disease (e.g., renal, pancreatic), which may require medical therapy prior to surgery and may influence anesthetic choices.
- Hepatic insufficiency which may debilitate the patient due to decreased hepatic production of clotting factors as well as reduced liver function, that may affect various critical aspects of patient homeostasis.
- Reduced thrombocyte counts, which may predispose the patient to coagulopathy.
- Electrolyte imbalances [1,5,8].
Radiographs and ultrasonography may be utilized in establishing a diagnosis, treatment plan and prognosis, as well as determining the patient’s degree of anesthetic and surgical risk.
Cardiovascular function should be thoroughly evaluated prior to anesthesia and surgery. Arrhythmias, murmurs, tachycardia, bradycardia and pulse abnormalities (pulse deficits or jugular pulses) should be investigated with radiographs, electrocardiology, echocardiography and evaluation of blood pressure [5,87].
Anorexia, disease and stress may all contribute to nitrogen imbalance. Starvation and disease may result in a hypermetabolic state, and stress may cause an initial hypometabolic state followed by a hypermetabolic state. Hypermetabolism increases the body’s protein requirement. Birds have a higher protein requirement than mammals. Protein demands are further increased because there is increased need for tissue repair, blood cell production and antibody production with surgery [5,87].
Carbohydrates are a nitrogen-sparing energy source and are recommended for correction of a stress-related negative nitrogen balance. A successful postsurgical patient requires a positive nitrogen balance to facilitate tissue repair, and a source of non-protein energy to meet their increased caloric requirements . Patients with a decreased blood glucose level should be supported intravenously with dextrose as part of their fluid therapy pre-and intraoperatively .
Resting basal metabolic rate (BMR) may be determined by using the formula BMR kcal/kg per day = (K)BW.75. Additional energy is required for growth, reproduction, disease and tissue repair. Severe trauma and sepsis may increase the patient’s energy requirements 1.5 to 3 times their resting requirement. There are several commercially available supplemental diets that can be utilized to meet these nutritional requirements, ranging from juvenile hand-feeding formulas to avian critical care diets  (see Chapter 7, Emergency and Critical Care).
Malnutrition may lead to obesity, vitamin A deficiency and other nutritionally related diseases. These conditions may pose anesthetic and surgical risks, and predispose the patient to infection, delayed healing and/or coagulopathies .
Birds normally maintain relatively low hepatic glycogen stores. Liver glycogen stores may decrease as much as 90% during a 24 to 36 hour fast and possibly more in small birds. However, it is important for the crop to be completely empty prior to anesthetizing the patient to prevent regurgitation and aspiration. Therefore, general guidelines include a short fast of 2 to 4 hours for birds <300 g body weight, 5 to 8 hours for birds >300 g body weight, 2 to 4 hours for frugivores and 24 to 36 hours for larger raptor species weighing 2 to 4 kg. It is generally recommended to leave water available until 1 hour prior to anesthesia .
Decreased gastrointestinal motility may alter these recommendations. The crop should be thoroughly palpated immediately prior to anesthesia. If surgery must be performed and the crop is not completely empty, fluid or liquefied food may be aspirated through a feeding tube and/or the head should be elevated during the surgery to prevent regurgitation and aspiration of crop contents. It is advisable to intubate these patients to protect the airway . Following intubation, cotton balls or gauze can be placed in the caudal pharynx to prevent reflux of crop contents.
Anesthesia and analgesia are indicated to promote patient comfort and reduce pre-, peri- and postoperative stress (see Chapter 8, Pain Management and Chapter 33, Updates in Anesthesia and Monitoring).
Patient positioning varies with the surgical approach. Lateral and dorsal recumbent positions are most common (Fig 35.1). Respiration may be impaired when the avian patient is placed in ventral recumbency. Procedures that may require ventral recumbency include excision of the uropygial gland, surgery of the pygostyle and excision of dorsal feather follicle cysts .
When the patient has been properly positioned, atraumatic adhesive tape such as masking or certain medical tapes may be used to secure the patient. Restraint boards are commercially available and are preferred by some surgeons. It is helpful to secure the patient to a platform that then may be repositioned as needed to facilitate intraoperative adjustments in surgical access .
Birds require movement of the keel and intercostal muscles for respiration, therefore, care should be taken to avoid placing any pressure on the thorax with surgical drapes, instruments or the surgeon’s hands .
Figure 35.1. The lateral and ventrodorsal patient positions are most commonly used for avian surgery. Care should be taken to avoid placing pressure on the thorax with surgical drapes, instruments or the surgeon’s hands, as birds require movement of the keel and intercostal muscles to expand the thorax for respiration. Tape that is not traumatic to skin and feathers, such as masking or certain medical tape, may be used to position the patient. (Espen Odberg).
Hypothermia is a significant concern, particularly in small avian species. Several heating systems exist including circulating water heating pads, electric heat pads, heated forced air systems and overhead heat sources. Some of these may not provide adequate supplemental heat to the patient and others may mechanically interfere with the surgeon and/or anesthetist [5,67] (see Chapter 33, Updates in Anesthesia and Monitoring).
Creating a Sterile Surgical Field
In preparation for surgery the feathers should be removed in a 2 to 3 cm radius beyond the edges of the surgical site (Fig 35.2). It may not be possible to remove all the feathers from the surgical field due to skin trauma, species-specific skin fragility, location of the surgical site, need to retain flight feathers or patient body size. Removal of the rectrices or remiges, which insert into the periosteum of the associated bones, may increase postoperative pain. These larger feathers may instead be wrapped with sterile non-adherent bandage material. The remaining feathers may be retracted from the surgical field with light adhesive tape such as masking tape. A small amount of alcohol may be used to lightly wet feathers and smooth them away from the surgical site ; however, alcohol should not be used when radiosurgery or electrocautery will be employed. Alternately, sterile, water-soluble lubricant jelly may be used to smooth the feathers out of the surgical field .
Figure 35.2. Prior to surgery, all feathers 2 to 3 cm from the surgical site should be removed. Standard aseptic technique applies to avian surgery. Chlorhexidine diacetate (0.05%), povidone iodine (1.0%) or chlorhexidine gluconate (4%) rinsed with alcohol and saline are all effective for presurgical skin disinfection. (Espen Odberg).
Standard aseptic surgical techniques apply to avian surgical procedures. Skin disinfectant scrub should be used to minimize the risk of bacterial contamination of the surgical site without damaging the skin. Chlorhexidine diacetate (0.05%) and povidone iodine (1%) have been found equally effective for skin preparation, and have no significant effect on wound healing. Chlorhexidine gluconate (4%) is equally effective when rinsed with alcohol or saline. Saline provides the benefit of not predisposing patients to hypothermia and does leave sufficient residual chlorhexidine solution bound to the skin. One study demonstrated that 50% of dogs developed erythema, edema, papules, wheals and weeping of serum from the skin when the skin was prepared with povidone iodine. This may suggest that chlorhexidine solutions are a less irritating class of disinfectants .
Aseptic preparation of the cloaca is difficult. Maximum disinfection can be achieved by irrigating the cloaca with chlorhexidine gluconate(4%), then infusing antibiotic ointment .
There are several lightweight surgical drapes available. Clear adhesive drapes allow the surgeon and anesthetist to monitor the rate and depth of respiration, and may be more effective in maintaining body temperature.
Surgical instruments for avian surgery must be appropriately sized and designed to atraumatically manipulate delicate tissue (Fig 35.3a, Fig 35.3b and Fig 35.3c). Microsurgical tools such as those utilized in human vascular surgery, ophthalmic instruments and instruments specifically designed for small veterinary patients may be used. Microsurgical instruments should be of a standard length, counterbalanced and have miniature tips (Fig 35.4a). The length allows for balancing in the hand (Fig 35.4b and Fig 35.4c). When utilized correctly, the arm provides stability while the fingers carefully move the tip. This balance, stability, and rounded shape allow for smooth, precise movement, thereby preventing any trauma to delicate tissues, blood vessels or nerves (Fig 35.4a-35.4f). Jeweler’s instruments are often used for their small size; however, these are usually not ergonomically designed for microsurgery. Several courses are available for microsurgical training. Microvascular and human plastic surgery techniques are particularly helpful with avian patients [1,4,5].
Figure 35.3a. A traditional small-animal thumb forceps with teeth is shown. This instrument has a curved tip and unique jaws for handling delicate tissues. (Greg J. Harrison).
Figure 35.3b. The forceps in Fig 35.3a have unique jaws (40x). The central row of teeth is elevated to fit into a depression on the opposite jaw. The apposing jaw has a recession for the ridge to fit in. On either side of the ridge and recession are alternating teeth and an offset space to receive a tooth. This setup maximizes tissue contact. Dr. Harrison has found this to be the most versatile instrument in avian surgery. (Greg J. Harrison).
Figure 35.3c. The basic minimal surgical pack should include top-quality instruments with carbide steel inserts. Minimal requirements for a basic surgical pack include Brown-Adson tissue forceps, Adson tissue forceps, smooth-tipped and toothed Bishop-Harmon tissue forceps (used for smaller patients), a larger pair of DeBakey tissue forceps, two or more curved-tip Halstead mosquito hemostats, tenotomy or small Metzenbaum scissors, and two needle holders. The recommended needle holders include a small Mayo-Hegar or Olsen-Hegar needle holder for 3 - 0 to 5 - 0 suture, and a smaller Castroviejo or Mathieu-type needle holder for 5 - 0 to 8 - 0 suture. The surgical pack also should include small, sterilized gauze pads and cotton swabs. (Espen Odberg).
Figure 35.4a. Bottom to top: Standard delicate-tissue, small-animal thumb forceps. Regular thumb forceps. Microsurgical thumb forceps. (Greg J. Harrison).
Figure 35.4b. Microsurgical forceps in Fig 35.4a showing the counterbalance and scooped-out area that fits over the web of the index-thumb finger area of the operator’s hand. Grasping the round handles approximates using a writing instrument. (Greg J. Harrison).
Figure 35.4c. The two tips available for microsurgical forceps (40x). On the left bottom is a fine needle tip that tends to slip if any tissue volume is grasped. On top is a circular or ring tip with titanium dust on the contact surface to aid in grasping. This greatly improves delicate tissue handling and reduces bleeding caused by slipping with the other forceps. (Greg J. Harrison).
Figure 35.4d. Needle holders. Top: Standard small-animal surgical needle holder. Right: Delicate-tissue needle holder. Left bottom: Microsurgical needle holder. The extra-fine tip and the round handles allow increased speed and accuracy of suturing when handling 6 - 0 to 10 - 0 swaged-on suture material. (Greg J. Harrison).
Figure 35.4e. Top to bottom: Delicate-surgery hemostat. Standard hemostat. Microsurgical hemostat. (Greg J. Harrison).
Figure 35.4f. Hemostat tips. Top: Delicate-surgery hemostat. Right: Microsurgical hemostat. Bottom: Standard hemostat. The microsurgical hemostat allows pinpoint grasping. Only the tiny area of concern is grasped. If needed these hemostats can be touched with the radiosurgery tips to coagulate the vessel contained within. Cauterization of surrounding soft tissue should be minimized to prevent unnecessary necrosis. (Greg J. Harrison).
Small, angled (60 - 90°) mosquito hemostats and hemostatic clip applicators are useful for avian celiotomies (Figs 35.4g-35.4j). These allow increased accessibility to viscera and blood vessels located deep within the coelomic cavity. Angled DeBakey neonatal vascular clamps [a] are useful for ovariectomy .
Figure 35.4g. Various hemoclip applicators. Left to right: Small hemoclip with 20° tip. Small hemoclip with 90° tip. Medium hemoclip with 20° tip. Medium hemoclip with 90° tip. Top: Microsurgical forceps for size comparison. (Greg J. Harrison).
Figure 35.4h. Loading the hemoclip applicators from a clip cartridge. (Greg J. Harrison).
Figure 35.4i. Comparison of a small hemoclip applicator (left), a medium hemoclip applicator (right) and a US 25-cent coin. (Greg J. Harrison).
Figure 35.4j. Side view of the hemostat applicator tips. Top: 90° tip. Bottom: 20° tip.
Sterile gavage and feeding tubes may be used for irrigation, to moisten tissue or to flush hollow viscera. Tuberculin or other small syringes may be used for suction, as some traditional suction units may traumatize delicate tissues. Mini-Frazier suction tips and Poole-type suction tips may be used in avian patients. The Pooletype suction tip may be fashioned from a rubber feeding tube by creating multiple fenestrations [1,4,5].
Abdominal retractors must adequately retract tissue without causing tissue trauma (Fig 35.5). Mini-Balfour and Alm retractors may be used in larger avian species such as macaws and Amazon parrots. Heiss retractors and ophthalmic eyelid retractors may be used in small avian species such as cockatiels and budgerigars. Lone Star retractors are lightweight and allow the surgeon to achieve retraction at several areas surrounding the surgical site [1,4,5].
Figure 35.5. Adjustable wound retractor frame and two tension bands hooked into one another. The location and tension on the band can be adjusted after inserting the hook into the surgical tissue. Then the band is slipped into a V-shaped slot in the frame at the ideal location and the desired pressure is applied. (Greg J. Harrison).
Hemostasis is of the utmost importance in birds. Minor hemorrhage can result in severe compromise to these small patients. Large blood vessels are located just below the dermis and care should be taken to either avoid severing or to preempt bleeding prior to transection of these vessels. Several tools exist to assist the surgeon. These include chemical cautery agents, metal clips, radiosurgery, electrocautery and lasers [1,5]. Hemoclips [b] are small, atraumatic, stainless steel clips applied with hemostat type applicators (Fig 35.4i). These applicators facilitate access into small, deep, difficult to reach areas [1,5]. Gel foam, surgical spears, Monsel’s solution [c], chemical cautery, collagen sheets, beaded polysaccharide powder [d] and direct manual pressure can assist in the control of minor hemorrhage [1,5].
Wound healing has been thoroughly evaluated in mammals and determined to occur in a sequential series of events. These include the inflammatory stage, fibroblastic stage, epithelialization phase, contraction phase and the remodeling phase. Cellular and vascular processes of the inflammatory stage have been evaluated in chickens and are similar to that described in mammals. Birds lack significant subcuticular tissue, therefore primary skin closure is often necessary. Excessive scar tissue does not typically form in birds (Fig 35.6) .
Figure 35.6. The scar from a previous surgery is visible (arrow). There may be minor adhesions between skin and the abdominal wall; however, scar formation is generally minimal in the avian patient. (Espen Odberg).
Radiosurgery utilizes high-frequency (2 - 4 MHz) alternating current to generate energy waves that create vibration and molecular intercellular heat (Fig 35.7a). This results in vaporization of water and rupture of affected cells while the electrode remains cool. The frequency may be manually set to cut tissues or coagulate blood vessels. Coagulation occurs when the current density dehydrates cells and coagulates the cellular contents (Figs 35.7b-35.7e) [4,5].
Figure 35.7a. Frequency chart. (Ellman International).
Figure 35.7b. The multifrequency radiosurgery generator for performing avian surgery with minimal hemorrhage. (Ellman International).
Figure 35.7c. This unit has been modified to allow multiple bipolar or unipolar hand pieces with a flick of a switch. (Ellman International).
Figure 35.7d. Advantages of radio wave surgery. (Ellman International).
Figure 35.7e. Versatility of radio wave surgery. (Ellman International).
When the radiosurgery unit is set for monopolar operation, it utilizes two electrodes: an active electrode and an indifferent electrode or ground plate. This concentrates the current density at the tip of the active (smaller) electrode. Monopolar radiosurgical technique is indicated for gross tissue manipulation in larger avian patients (>2 kg). The ground or indifferent electrode should be placed in contact with the patient as close to the surgical field as possible. Patient contact is improved with the application of a contact gel to the patient and ground. Alternatively, the ground plate may be permanently mounted under the surgery table and the patient placed on a non-metal material such as a towel. Such material will prevent thermal burns to the dependent aspect of the patient. This is particularly important in thin patients with prominent bony sites that provide small conduction points that can generate high localized temperatures. The active electrode must be kept clean and free of char and debris. An excessive amount of char or debris will interfere with conduction, thereby creating drag through the tissue, inhibiting cutting action and increasing coagulation. This may delay wound healing and predispose the patient to wound dehiscence. Several types of electrode tips are commercially available. Ball-tipped electrodes create significant tissue destruction for fulguration and coagulation of large amounts of tissue; loop electrodes are useful to obtain tissue biopsies and surgically excise tissues; and fine wire electrodes are utilized for incisions. It is useful to have some tips (such as those used in dentistry) that function in a wet field for effective coagulation during hemorrhage [4,5].
If cryosurgery is performed in conjunction with radiosurgery, it is important to note that radiosurgical tools will not work on frozen tissues [4,5].
Bipolar radiosurgical forceps are useful, particularly in small avian patients (<2 kg) (Fig 35.7f). These allow for hemostatic control at the tip without the use of a ground plate, as one of the tips serves as the active electrode and the other as the indifferent electrode. The current passes from one tip, the active electrode, to the other, the indifferent electrode, without passing through the entire patient. Closer proximity of the two electrodes alters the transmitted wave currents from those transmitted by monopolar electrodes, resulting in more precise control and less reflux hemorrhage. The cut settings are used for tissue incisions. The cut/coagulation settings are indicated for vessels that are difficult to coagulate and for controlled cutting with coagulation properties (ie, as for organ biopsy). The coagulation settings are used for tissue fulguration. The material and design of the bipolar forceps, as well as proper calibration of the machine, determine the efficiency and performance of bipolar radiosurgery (Fig 35.7e) [4,5].
Figure 35.7f. Various bipolar forceps. Left to right: The Harrison modification and three custom ring-tip models. (Espen Odberg).
Bipolar forceps may be used to make primary skin incisions, to incise through muscle with minimal hemorrhage, and to coagulate cutaneous blood vessels prior to incision with a scalpel blade or scissors. The skin may be grasped and elevated with thumb forceps, then incised with bipolar radiosurgical forceps. This incision is then extended by inserting the indifferent electrode of the bipolar forceps subcutaneously to the full extent of the desired incision. The forceps are then apposed with the skin between them and the incision performed is extended by dragging the tips over the full thickness of the skin. This will incise the skin and coagulate the blood vessels. Correct settings and proper use of radiosurgery does not cause discoloration of the skin lateral to the incision (ie, if the skin is discolored, tissue damage has occurred and primary intention healing is unlikely) .
Tissue incisions may be performed with monopolar tips as well. Wire-type tips may be used as an "electrosurgical scalpel". The current should be initiated prior to touching the tissue. Often, higher settings are necessary in birds as compared to mammals due to the lower water content of the skin, which may result in less coagulation of associated vessels and hemorrhage. Cutting ability may be improved in very dry skin by moistening the skin with saline [4,5]. Feather follicles and their associated blood supply should be preserved whenever possible .
When using the bipolar forceps for hemostasis, the forceps tips are relaxed as current is applied, providing a small gap between the two sides through which the radio current flows, thereby sealing the vessel. It is important to clean the forceps tips frequently. Accumulated blood and tissue can adhere to the clot and subsequently destroy it when the forceps are removed. Forceps tips are currently being developed with new materials that do not accumulate blood and tissue. When using the coagulation settings, the vessel may retract within the tissue due to vasospasm. This results in temporary hemostasis until the vessel relaxes, but hemorrhage may recur. A new modification that can be used with an endoscope has been developed (Fig 35.7g and Fig 35.7h).
Figure 35.7g. The trigger handle allows endoscopic bipolar applications of a radio frequency instrument. (Ellman International).
Figure 35.7h. The trigger handle has directional control. This illustration is from use in human disc disease therapy. (Ellman International).
Light Amplification by the Stimulated Emission of Radiation (LASER) relies on the production of electromagnetic radiation in response to photon emission by a lasing medium. Electrical energy excites a lasing medium (carbon dioxide, diode or argon) contained within an optical laser chamber, which, upon returning to a steadier electrical state, loses energy and generates photons in the form of electromagnetic radiation or light. These photons are directed from the optical laser chamber as monochromatic electromagnetic radiation transmitted via a series of lenses and delivery fibers in a focused and controlled laser beam. The type of lasing medium will alter the wavelength and frequency of the radiation [38,69].
Carbon dioxide and diode lasers are most commonly used in veterinary medicine. Both produce an immediate region of vaporization, surrounded by a zone of irreversible photothermal necrosis and a zone of reversible edema. Laser surgical incisions seal blood vessels, nerves and lymphatics for controlled hemostasis, analgesia and postoperative edema. Carbon dioxide lasers operate at a wavelength of 10,600 nm. They may be operated with a focused beam, ideal for cutting, or a defocused beam, used for vaporizing tissue. They provide accurate, noncontact surgery with minimal tissue penetration and minimal collateral thermal injury (0.05 - 0.2 mm from the incision), as compared to the diode laser, which offers a zone of thermal injury of 0.3 to 0.6 mm from the incision. Thermal penetration is relatively superficial, penetrating only 50 to 100 µm in depth [38,54,69].
Diode lasers operate at a wavelength of 635 to 980 nm. They may be operated in direct contact with tissue (contact mode) or at a distance from tissue (non-contact mode). They have the ability to operate in a fluid environment (intestinal tract, fluid-filled coelom) and provide improved hemostasis, with the ability to coagulate blood vessels up to 2 mm in diameter, as compared to the CO2 laser, which coagulates blood vessels up to 0.6 mm in diameter. Operation results in deeper tissue penetration and is relatively less precise. Diode lasers have been used for photocoagulation of retinal and other ocular tissues, chromophores enhanced tissue ablation and coagulation, laser welding and photodynamic therapy. In addition, the diode laser has the fiberoptic ability to operate with several endoscopes [38,54,69].
Laser is particularly useful for avian surgery, where hemostasis is of great concern. Surgical indications include salpingohysterectomy, orchidectomy, and limb amputation. It is also beneficial in the excision of granulomas, abscesses, and neoplasms. Endoscopic diode laser techniques provide minimally invasive access to several anatomic sites as well as endoscopic hemostatic control. Superficial lung and air sac granulomas within the cranial thoracic, caudal thoracic and abdominal air sacs have been successfully ablated with the 810-nm diode laser [21,37,61].
Illumination and Magnification
Avian surgery often requires delicate handling of small structures. Coelomic surgery is performed within a deep cavity, which obstructs visualization. Therefore, magnification and illumination equipment are essential (see Chapter 1, Clinical Practice). The ideal avian surgical light source provides optimum illumination with minimal heat transfer to the patient that may result in tissue dehydration and surgeon discomfort. (Ed Note: Although overhead lights that produce significant heat have been shown to be effective in helping to prevent hypothermia during avian anesthesia, forced warm air blankets also are effective and do not have the disadvantage of tissue desiccation and overheating of the surgeon). The small size of the avian patient necessitates intense light, precisely focused. This often requires changing the angle of the light to provide illumination and avoid shadows. A three-headed, flexible fiberoptic light source provides ideal illumination and the ability to change the focal area of the light. Often, 250-watt bulbs with no less than 20,000 lux are required [1,4,5].
Ocular head loupes and operating binoculars with a halogen light source also may be used for magnification and illumination. These allow the surgeon to set the light source on the surgical site, and magnification and illumination move with the surgeon. Operating microscopes are useful for avian patients, particularly those weighing less than 1 kg, and are advantageous for handling blood vessels in larger birds as well. An operating microscope with a lens objective approximately 150 power and a 12.5 power binocular objective is most useful [1,4,5].
A less expensive but also less effective option for increased magnification and illumination includes adjustable magnifiers with attached lights available for sewing and other home uses.
Suture Materials and Adhesives
Significant information is available regarding appropriate selection of suture material in veterinary and human medicine. Suture material utilized in birds must be minimally reactive and of an appropriate size. Tissue reaction to five suture materials has been evaluated in pigeons at 3, 7, 15, 30, 60, 90 and 120 days following implantation in the body wall. These include polyglactin 910, polydioxanone, monofilament nylon, medium chromic catgut and stainless steel. Pigeons developed a marked granulocytic inflammatory response to medium chromic catgut that diminished during the evaluation period. The suture was still present at the end of the study, indicating prolonged absorption of the material. Polyglactin 910 caused the most inflammatory reaction and was the most quickly absorbed, being completely gone by day 60. Polydioxanone, like polyglactin 910, is absorbed by hydrolysis. Unlike polyglactin 910, however, it caused minimal tissue reaction and absorption was occurring by day 120. Nylon and stainless steel are non-absorbable materials that caused minimal tissue reaction. However, the stiffness may make them mechanically irritating to surrounding tissues, and these were more often associated with hematoma, seroma and caseogranuloma formation.
This study concluded that chromic catgut should be avoided; slowly absorbed monofilament and synthetic materials absorbed by hydrolysis rather than proteolysis are recommended when prolonged wound healing is expected. Rapidly absorbed, braided, synthetic suture materials absorbed by hydrolysis are recommended when the benefit of rapid absorption outweighs the disadvantage of possible pronounced inflammatory reaction. Monofilament suture material has the advantage of minimizing trauma and cutting of tissue when compared to multifilament material. Taper-point needles are usually indicated in avian surgery, as compared to cutting needles to prevent tearing of tissues being sutured. Cutting needles may be useful for suturing thicker, tougher tissues such as the feet of larger species [4,5,10].
Cyanoacrylate tissue adhesives hold tissues in apposition to allow healing. The cyanoacrylate monomer is a liquid that polymerizes in a small amount of water present in tissues. However, it is important not to allow the acrylic to run between the apposed tissues, as this physical barrier will delay wound healing. One should be cautious when using these adhesives in the presence of anesthetic gases with which they are reactive. They may also cause ocular irritation and vomiting in avian patients. The fumes of some cyanoacrylate tissue adhesives may cause respiratory irritation as well .
Postoperatively, the patient should be placed into a temperature-controlled incubator once it is able to stand without ataxia. Temperature should be set according to each individual’s optimal requirements (27 - 30° C or 81 - 86° F for most psittacines) and supplemental humidified oxygen is beneficial to those patients at risk for hypoxia/hypercapnea during recovery [1,5,9,41].
Perches should be avoided until the bird has recovered sufficiently to balance and grip well. Once the patient can balance and grip, perches of low height are recommended. Food and water are not introduced until the patient has fully recovered to prevent regurgitation and aspiration [1,5,9,41].
The likelihood of postoperative self-trauma varies with the species, the individual patient and the surgical procedure performed. Avian patients generally do not traumatize their surgical incisions. Some clinicians advocate leaving longer-than-average suture ends to allow the bird to groom these as they would a feather [1,5,9,41].
Occasionally an Elizabethan or other collar is necessary to provide a mechanical barrier to self-induced trauma to the surgical site. In all cases where a collar is first applied, the bird should be monitored following the collar application. Agitation, depression, or inability to access food or water must be noted and corrected. If the bird can still traumatize the surgical site, collar adjustment also would be needed. Applying the collar prior to surgery may enhance acceptance of an Elizabethan or foam collar. This allows the bird to adjust to the collar, thus minimizing postoperative stress. Antianxiety or sedative medications such as diazepam may be given prior to collar application to decrease stress. Initially applying a small collar and increasing the size as necessary also may improve patient acceptance. Some birds will not tolerate restraint collars and customized body suits may be used to prevent self-trauma [1,5,9,41].
Soft Tissue Surgery
Birds have a relatively thin, dry epidermis. In feathered regions, the skin may be only 10 cell layers thick. The dermis is loosely attached to the underlying muscle fascia with very little subcutaneous tissue except in the distal extremities where it is firmly adhered to the underlying bone .
Constriction and Avascular Necrosis of the Digits
Avascular necrosis of the phalanges of the pelvic limbs may occur secondary to circumferential constriction caused by fibers, scabs or necrotic tissue. These constrictions compromise vascular flow to and from the distal phalanx, leading to edema and necrosis (Fig 35.8a and Fig 35.8b). If detected early, the toe may be salvaged and amputation avoided. This condition is particularly common in pediatric patients. Proposed etiologies include low relative humidity, egg fiber-related strictures from hatching, septicemia and ergot-like intoxication. Increasing the environmental humidity and applying topical creams to promote hydration of the affected tissue may be effective in resolving early lesions. Eschars should be debrided and the digit cleaned and bandaged with a hydroactive dressing and allowed to heal by secondary intention. If tissue fibers are the inciting cause, a full-thickness linear skin incision should be made over the dorsal aspect of the constricted region. This area is then bandaged with a hydroactive dressing to prevent scab formation. Complete healing may require weeks to months. A circumferential excision of the constricted region followed by anastomosis of the skin may be performed. The constricted tissue is surgically removed with a scalpel blade. One to two subcutaneous sutures are placed to prevent excessive tension on the skin repair. The skin edges are apposed with several simple interrupted sutures placed superficially to prevent disruption of the vascular supply by resulting eversion of the skin edges, which will delay wound healing. After the skin edges are apposed, 2- to 3-mm superficial release incisions should be made on the lateral and medial aspects of the digit at the site of the anastomosis. This will allow postoperative swelling to occur without constriction. A hydroactive dressing is applied and the digit bandaged. Magnification and illumination such as a head loupe or operating microscope are useful to visualize the fibers [1,9].
Figure 35.8a. Avascular necrosis of the phalanges can occur as a result of circumferential constriction due to fibers from cage bedding or as a condition of undetermined etiology. In the case of this bird, cloth fibers became entwined around the foot, leading to the visible digit swelling and potential for necrosis of the digits. Removal of the constricting fibers, appropriate topical antibiotics and bandage application are necessary to treat this condition. (Bob Doneley).
Figure 35.8b. Manmade fibers tend to entrap digits. The threads are removed using 40x magnification and a bent-tip hypodermic needle as a cutting tool. When the constricting band is not accompanied by foreign material, treatment is similar to that described in Fig 35.8a. The circumferential bands may require debridement and suturing. (Greg J. Harrison).
If the distal phalanx has developed complete avascular necrosis, amputation is necessary. Amputation should be performed just proximal to the proximal end of the necrotic tissue, where a good vascular supply still is present. An incision is made in the skin and subcutaneous tissue circumferentially. One or two sutures are placed in the subcutaneous tissue to relieve tension on the skin incision. Several simple interrupted sutures are placed in the superficial epidermis to prevent eversion of the skin edges, which will delay healing. The digit is bandaged and sutures removed in 10 to 14 days [1,9] (see Amputation of Digit later in this chapter).
It is best to avoid the use of electrocautery or radiocoagulation to prevent damage to the minimal vascular supply of the digits. If a tourniquet is utilized to control hemorrhage, it should be used for only a limited time to avoid vascular compromise [1,9].
Passerines are prone to developing avascular necrosis of the pelvic limbs or digits due to entanglement with synthetic fibers such as nesting string. Microsurgical tools or a bent 25-gauge needle may be used to remove the constricting fibers. The tip of the needle can be used to elevate the fibers and the edge of the needle used to severe the material. A hydroactive dressing is applied and the area bandaged [1,9].
Passerines also may develop constrictions secondary to hyperkeratosis or to the development of excessively large scales over the pelvic limbs and digits. Malnutrition and Knemidokoptes sp. infection have both been implicated as etiologies. These conditions may predispose the patient to Staphylococcus spp. infections. In most cases, skin lesions will resolve with correction of nutritional problems or treatment with ivermectin. In severe cases, it may be necessary to surgically debride these hyperkeratotic lesions or enlarged scales. Microsurgical instruments and magnification are useful for manipulating these small structures. Antibiotic emollient creams will soften and hydrate the skin while treating bacterial infection [1,9].
Feather cysts are usually formed as a result of injury to or deformation of the follicle [36b]. Direct trauma, mechanical and chemical cautery also are inciting causes.
Damage to one side of the follicle may result in asymmetrical feather growth. The developing feather may then grow in an arch back toward the body, forming a feather cyst (Figs 35.9a-35.9i). Certain species of canaries, particularly the Norwich, Gloucester and their crossbreeds, may develop cysts as a result of abnormally formed feathers (Fig 35.10). These birds have been genetically selected to produce a downy, soft feather type that predisposes them to feather cysts. Malnutrition, viral, bacterial and parasitic infections may result in formation of feather cysts as well [1,9,36b].
Figure 35.9a. Feather cysts in parrots usually form as a result of injury to the follicle. Direct trauma to the feather follicle can result in abnormal feather growth, thus promoting feather cyst formation. Improper wing trim, malnutrition, viral, bacterial and parasitic infections may result in the formation of poor-quality feathers that are easily damaged. This cyst has formed in the follicle of the dorsal major covert overlying primary remex VIII. While the cyst is dorsal, this follicle inserts on the ventral aspect of the major metacarpal bone. The underlying primary feather structures form the strongest boundary, so the cyst herniates dorsally. Approaching the cyst from this dorsal aspect fails to address the germinal tissue found at the point of insertion. (Greg J. Harrison).
Figure 35.9b. Incising alongside the cyst using radiosurgery bipolar forceps. (Greg J. Harrison).
Figure 35.9c. Freeing the cyst dorsally from surrounding feather structures. (Greg J. Harrison).
Figure 35.9d. Next the ventral surface of the wing is incised between primary VII and VIII, allowing access to the insertion of the cystic follicle on the ventral aspect of the metacarpal bone of the manus. (Greg J. Harrison).
Figure 35.9e. Retractor bands used to improve the view and hold the unaffected follicular tissues out of the way of the radio wave’s energy field to avoid damage. In Harrison’s opinion, feather damage and failure to resect the point of insertion are the major causes of cyst surgery failure and cyst recurrence. (Greg J. Harrison).
Figure 35.9f. Dissection of the follicular tissue. Retractor bands are repeatedly relocated to minimize trauma during cyst removal. (Greg J. Harrison).
Figure 35.9g. The freed follicle is traced to its insertion and the nutrient vessel is coagulated. (Greg J. Harrison).
Figure 35.9h. The full cystic follicle is removed intact.
Figure 35.9i. Cyst removed intact and microsurgical needle holder. (Greg J. Harrison).
Figure 35.10. Multiple feather cysts can occur on the body, either over a regional area or in a particular feather tract. Multiple cysts may be removed surgically using an elliptical or fusiform excision followed by primary closure with a simple continuous pattern using a monofilament suture. (Espen Odberg).
The surgeon should examine the cyst to determine whether it contains a viable or devitalized feather. Perform an initial evaluation of the feather by making a small incision at the distal aspect of the cyst and examining the contents. Every attempt should be made to salvage viable feathers and tissue, particularly those involving tail rectrices and flight feathers [1,9].
If excision is required, use of a scalpel blade offers the benefit of complete excision of the affected follicle without damage to adjacent follicles. Damage to adjacent feather follicles and/or their blood supply may disrupt feather formation and result in the formation of additional feather cysts. Radiosurgical fulguration has been performed successfully; however, the adjacent feather follicles may be damaged due to difficulty in controlling the extent of tissue destruction. Feather cysts typically have good vascular supply, so hemostasis is required.
A tourniquet, direct manual pressure applied to the surgical site or polysaccharide beaded may aid in hemostasis. The site may be sutured or left to heal by second intention and bandaged with a hydroactive dressing. As adjacent feathers begin to regrow, debris should be removed carefully and the bandage changed frequently to prevent interference with developing feathers. Laser excision may improve hemostasis. Occasionally the cyst contains necrotic material but the follicular epithelium is not damaged, making new feather growth possible. In these cases, the follicle is incised and necrotic material removed. The follicle is then irrigated with sterile saline and the edges of the incision apposed. The site may be bandaged and local and/or systemic antibiotic therapy initiated. New feather growth must be carefully monitored for formation of cysts and disfigurement of new feathers. Feathers may fail to regrow if the epithelium has been severely damaged [1,9].
Occasionally a cystic follicle may be salvaged by marsupialization, particularly if there is a single cyst or a large follicle. An incision is made over the center of the cyst with a scalpel blade parallel to the direction of feather growth. Hemorrhage is controlled with a tourniquet, manual pressure or by ligation. Radiocautery or chemical hemostatic agents may damage the epithelium and further damage the follicle. The contents of the cyst are removed and the lining sampled for cytology and bacterial culture. Redundant tissue is excised and the follicle irrigated with sterile saline solution. The margin of the cyst is then sutured to the adjacent skin using a simple continuous pattern with a fine monofilament suture. New feather growth must be carefully monitored for formation of further cysts or disfigured feathers. Feathers may fail to form if the epithelium is severely damaged [1,9].
Occasionally multiple feather cysts are present on the body, either over a regional area or in a particular tract. Multiple cysts may be removed using an elliptical or fusiform excision followed by primary closure with a simple continuous pattern using a monofilament suture material. Radical excision of an entire pteryla of affected feathers has been described. This is typically necessary in canaries. A fusiform incision is made around the affected pteryla. The primary vascular supply to the tract, and any large blood vessels are ligated or coagulated. The affected follicles are removed along with the surrounding skin. The remaining skin edges are apposed using a simple continuous pattern with a monofilament suture [1,9].
Feather cysts of the tail may be severe and disfiguring. Birds may traumatize these and develop secondary infections. Cysts can be excised as described previously. Amputation of the pygostyle is an option in those patients suffering from multiple cysts or those that have severe trauma to the surrounding soft tissues and underlying bone. This is performed by blunt dissection to the coccygeal vertebrae and disarticulation at the sacrococcygeal junction. Soft tissues are closed routinely and care should be taken not to enter the cloaca. Intraoperative hemorrhage and postoperative pain may be severe, and hemostasis and analgesia are crucial to a successful outcome [1,9].
Skin and Follicular Biopsy
Skin biopsy is indicated as part of a diagnostic process for dermatoses including feather dysplasia, feather destructive behavior, auto-mutilatory conditions, ulcerative dermatitis, hyperkeratinization and feather loss (see Chapter 13, Integument). Selection of biopsy sites is crucial to accurate diagnostic results. A sample with an actively growing feather, an entire follicle and surrounding skin should be obtained for conditions affecting the feathers. The surgical site should be gently prepared, avoiding vigorous scrubbing that may irritate the skin and alter the histopathology results. The follicle is grasped with atraumatic forceps and the feather, follicle and skin excised with scissors or a blade. Disposable skin punch biopsy instruments also work well. Minimal pressure should be exerted with these biopsy punches due to the thin avian skin and absence of significant subcutaneous tissue. It is best to avoid cautery prior to excising the sample to prevent cellular and tissue changes to the edges, which may complicate histopathologic analysis. Radiosurgery may be used to control hemorrhage after the sample is obtained. Closure is routine .
Cranial Skin Defect Repair with an Advancement Pedicle Flap
Soft and hard tissue injury to the cranium may occur due to trauma from various sources including predator attack or attack from other birds, ceiling fan injuries and cage trauma. Species that commonly "flush" such as quail may be susceptible to cranial trauma if the caging does not have significant height to allow for flight. Soft tissue injuries that expose the cranium may result in chronic, non-healing wounds and devitalized cranial bone, which impedes formation of granulation tissue and epithelial migration. The skin covering the cranium is firmly adhered to the cranium. Primary and secondary closure of larger wounds may be difficult once skin edges have begun to fibrose. In addition, closure may create tension when apposing the skin edges, creating deformation of the eyelids and even exposure keratitis. Some wounds may be allowed to heal by second intention under a hydrophilic bandage material [27,73].
A pedicle advancement flap is preferable to simple closure to surgically resolve larger defects to the soft tissue covering the cranium. Advancement flaps remain continuous with the donor site thereby maintaining blood supply to the subdermal plexus within the flap. Pedicle advancement flaps have a greater chance of remaining viable, as compared to free grafts, particularly when the recipient site is poorly vascularized. In addition, full thickness skin and subcutaneous grafts will provide normal feather coverage if they contain pterylae [33,55,62-65,73].
Initially, the wound is assessed to determine the degree of necrosis of the skin and cranial bone, and to examine the size of the defect to be repaired. The cranial skin is undermined and the skin edges are debrided, removing just enough skin to obtain a good vascular supply. If necessary, small rongeurs may be used to carefully remove devitalized bone; obviously, the cranium should not be completely penetrated. Initiating two skin incisions at the lateral aspects of the caudal end of the defect creates the pedicle flap. These incisions are continued caudolaterally over the cervical region. Divergence of the lateral incisions creates a wider base that increases the blood supply to the subdermal plexus, and compensates for the tendency for inadvertent convergence of the incisions when applying lateral skin tension where the skin is more mobile [33,55,62-64]. These incisions should be made with either a scalpel blade or sharp surgical scissors to maintain integrity of the ends of the blood vessels that will be advanced cranially. The pedicle is undermined bluntly to prepare the flap for advancement. The skin flap is advanced rostrally and the skin edges apposed with small monofilament suture in a simple continuous or interrupted pattern using a taperpoint needle [27,73].
If the defect is too large to correct with a single surgery, the initial procedure should close as much of the defect as possible and the remaining defect can be covered with a hydroactive dressing. A second surgical flap may be created or a staged closure of the defect using horizontal mattress sutures may be performed to completely repair the defect.
Repair of Ulcerative Lesions of the Sternum (Carina of the Keel)
Ulcerative lesions to the carina of the keel are most often traumatically induced (see Chapter 1, Clinical Practice). Thermal burns, foreign bodies, poxvirus, mycobacteriosis or other stressful situations such as heat and overpopulation have been implicated as well. Improper wing trimming, particularly in heavier bodied birds (African grey parrots and Amazon parrots) may cause the bird to impact the floor when it attempts to fly. This trauma may create a bruise or a laceration of the skin over the carina. Scars from previous traumatic episodes are often evident upon routine physical examination. Auto-mutilation of the tissue overlying the carina may occur as well. Secondary bacterial infection, often involving anaerobes, is common in this location .
Traumatic lesions of the carina often heal readily if the patient is prevented from falling and re-injuring the site. Conversely, repeated trauma and/or auto-mutilation may cause more severe and chronic lesions. These lesions may require extensive surgical debridement. Extensive lesions may prevent primary closure and may heal by second intention.
Surgical correction is accomplished with the patient in dorsal recumbency. The feathers are removed in a 2-cm diameter around the circumference of the wound and the area surgically prepped. The skin and subcutaneous tissues are debrided until healthy tissue is encountered. It may be necessary to debride devitalized pectoral muscle and affected portions of the carina of the keel. Radiosurgery may be used for hemostasis. Tissue and bone samples should be submitted for bacterial culture and histopathologic examination. The elevated origins of the pectoral muscles are sutured together over the keel or anchored to the cartilaginous portion of the keel in an interrupted horizontal mattress pattern with absorbable monofilament suture. The skin is closed in a simple interrupted or continuous pattern with monofilament suture. There is often considerable tension on these incision sites, therefore, it may be necessary to place tension-relieving sutures lateral to the incision. One method described involves placing interrupted horizontal mattress sutures through the skin and pectoral muscle tied over gauze sponges just lateral to the medial incision. The wings may be bandaged to the body to prevent extension and movement that would place additional tension on the suture site, and a restraint collar or body suit is usually necessary if auto-mutilation has occurred. Defects that are too large to close surgically may heal by second intention. Gentle irrigation and frequent bandage changes with a sterile hydrophilic dressing will assist in healing .
Xanthomatosis results from the accumulation of lipidladen macrophages, giant cells, free cholesterol and variable degrees of fibrosis. Xanthomas often occur at the distal wing, but have been found in other locations as well. These masses may be locally invasive and wide margins may be necessary to completely excise and prevent recurrence. Some birds may mutilate these lesions, causing ulceration and secondary infection. Elevated serum cholesterol, trauma and genetic predisposition in some species have been implicated in the formation of xanthomas. Dietary correction may be curative in some species and in some individuals. However, very large, painful, hemorrhagic or infected xanthomas often require surgical resection.
Masses may be removed with bipolar or monopolar radiosurgery, taking care to avoid damage to remaining feather follicles and their blood supply. The site may be closed if there is enough remaining tissue or allowed to heal by second intention and bandaged with a hydroactive dressing (Figs 35.11a-35.11g). If extensive subcutaneous tissues and bone are involved, amputation of the affected area may be necessary .
Figure 35.11a. Xanthomas often occur at the distal wing, but have been found in other locations. Note the balding plantar foot patterns and the discoloration of the feathers. These are indicative of malnutrition and related disorders. (Espen Odberg).
Figure 35.11b. Xanthomas that are well demarcated and/or pedunculated may need to be excised. (Espen Odberg).
Figure 35.11c. Xonthomas that are closely associated with feather follicles may be excised, being cautious not to cause follicle damage. (Espen Odberg).
Figure 35.11d. Removal of such welldefined distal wing xanthomas can be performed by making a small skin incision and gently teasing the contents out with a sterile cotton swab. (Espen Odberg).
Figure 35.11e. Hemorrhage can be controlled with a bipolar or monopolar radiosurgical unit. (Espen Odberg).
Figure 35.11f. After using radiosurgical hemostasis allow a few moments to make sure no oozing occurs. (Espen Odberg).
Figure 35.11g. The skin is closed in a simple interrupted suture pattern with a monofilament suture. (Espen Odberg).
The uropygial gland is located dorsal to the tail. It is absent in Amazon parrots (Amazona spp.) and the hyacinth macaw (Anodorhynchus hyacinthinus) and may be reduced in size in some cockatiels. Disease of this gland and/or its papillae is not uncommon and surgical correction may be necessary. Absence of papilla feathers may indicate a problem with glandular function. Left untreated, a gland may rupture, causing inflammation and significant scar tissue formation. Simple impaction of the gland may respond to medical therapy and gentle expression of the contents. If the impaction cannot be alleviated by conservative therapy, small incisions may be made over the affected lobe(s) of the gland, the contents expressed, and the gland irrigated with saline. Antibiotics and analgesics may be indicated during recovery . Neoplastic conditions of the uropygial gland with secondary infection occur with some frequency (see Chapter 13, Integument).
Chronic impaction and/or infection unresponsive to medical therapy and neoplasia of the uropygial gland may require surgical removal of the affected gland. The patient is placed in lateral or semi-ventral recumbency. Intermittent positive pressure ventilation and close monitoring of respiration is necessary when positioned ventrally to ensure movement of the sternum is not reduced and respiration not impaired. The head may be elevated and a pad may be placed under the tail, with the tail rectrices taped in place to elevate the sacrum and improve exposure and visualization of the uropygial gland. The surgical site is aseptically prepared. The gland is bilobed and each lobe receives its vascular supply from a vessel that branches at the cranial, middle and caudal portions of the gland. These vessels and other surrounding vessels require ligation or bipolar radiocoagulation. The gland may extend deep to the synsacrum and caudally to the insertion of the tail feathers .
A fusiform incision is made via unipolar or bipolar radiosurgery around the circumference of the gland. This is initiated caudal to the papilla and continued craniolaterally along both sides of the gland. Dissection of the gland is initiated at the caudal aspect of the gland and extended circumferentially and cranially until the gland is removed. Mosquito hemostats or thumb forceps may be used to apply gentle traction on the gland, facilitating removal. The strongest attachments are associated with the muscle fibers at the cranial border of the gland. Hemorrhage must be strictly controlled by radiocoagulation, manual pressure and/or hemostatic products . The deeper fascia is closed with absorbable monofilament suture in a simple continuous or interrupted pattern, depending on the amount of tension present. Subcutaneous and skin closure is routine. Extensive tissue trauma, neoplasia or rupture of the uropygial gland may require additional dissection and debridement. An additional caudal incision perpendicular to the dorsal midline incision may be necessary. If the remaining defect is too large to allow full closure, staged closure or healing by second intention may be necessary. Any open defects should be bandaged under a hydroactive dressing to promote granulation and prevent exposure. Antibiotics and analgesics should be administered as appropriate to each patient. Dehiscence, damage to the follicles of the rectrices and infection are potential complications (Figs 35.12a-35-12e) .
Figure 35.12a. The feathers of the uropygial gland and the feathers of the skin dorsally should be removed prior to surgical removal of the gland. Care must be taken when removing these feathers to prevent gland rupture or hemorrhage. Once the feathers of the papilla are removed, material may drain from the gland. This material will need to be cleaned and a gentle routine surgical scrub performed prior to surgery. A fusiform incision is made around the uropygial gland papilla, remaining dorsal to the tail feathers. (Espen Odberg).
Figure 35.12b. The tissues underlying the skin are gently dissected and the skin flap is gently reflected dorsally and cranially. Hemorrhage is controlled by coagulation with a bipolar radiosurgical unit. The difference in the appearance between the left (impacted) and the right (non-impacted) side of the gland are apparent in this picture. (Espen Odberg).
Figure 35.12c. The largest vessels of the uropygial gland are located on the cranial aspect of the gland along the muscular attachments. By utilizing the duct as a handle and working caudal to cranial, the underlying vessels can be visualized and coagulated with the radiosurgical unit. Removing the gland requires careful dissection and thorough examination for bleeding vessels. (Espen Odberg).
Figure 35.12d. The skin is apposed using 5 - 0 monofilament nonabsorbable suture. Beginning the sutures in the middle of the incision will allow for easier alignment of the skin flap. (Espen Odberg).
Figure 35.12e. The appearance of the incision following resection of the uropygial gland and completion of the skin closure (see Fig 35.12d). (Espen Odberg).
Treatment and surgical intervention in severe presentations of pododermatitis are outlined in Chapter 13, Integument.
Surgery of the Upper Respiratory System
Birds may develop rhinoliths secondary to chronic rhinitis and malnutrition. These masses are often formed from desiccated secretions and debris and cause a physical obstruction to respiration. The nares and opercula may become severely eroded and disfigured and damage is often permanent. Clinical signs include sneezing, upper respiratory sounds, inflation of the associated infraorbital sinus, nasal discharge and picking at the affected nares with a toenail. The nares will appear impacted with material, but it is important to recognize the normal anatomy and not mistake the operculum for abnormal material (Fig 35.13a and Fig 35.13b). A strong light source, magnification and gentle probing may be required to identify a small rhinolith (Fig 35.14a and Fig 35.13b). Surgical head loupes with halogen light sources are particularly useful [1,9,71].
Nasal tissues are friable and vulnerable to traumatic probing, which will also predispose the mucosa to infection. Prior to attempting removal, warm saline drops should be applied to the affected naris and associated rhinolith. This will ease removal and decrease trauma to the associated tissues. A stainless steel aural curette may be used to gently elevate and remove the mass from the naris. A lacrimal cannula may be used in smaller avian patients such as budgerigars and passerines. Samples should be obtained for cytology, and bacterial and fungal culture. The nares should be flushed with a disinfectant (e.g., dilute chlorhexidine or F10 solution) after removal of the bulk of the mass to remove any small pieces or material and to assist in resolution of any pathogens . Appropriate antibiotic or antifungal therapy should be initiated and subsequent flushing performed. Malnutrition should be treated through diet correction. Proper air filtration, humidification and frequent bathing are necessary to prevent recurrence. The rest of the respiratory system should be thoroughly evaluated to identify other concurrent disease [1,9,71].
Figure 35.13a. Normal naris in a lovebird.
Figure 35.13b. Avian patients with malnutrition and subsequent squamous metaplasia and chronic respiratory infections can develop rhinoliths. Erosions of the operculum and nares may result in permanent disfigurement of the nostrils, as shown in this lovebird.
Figure 35.14a. An African grey demonstrates a mild or early stage of accumulation of debris on the operculum. Left untreated, this condition would likely progress to a rhinolith.
Figure 35.14b. A normal naris in an African grey on a formulated diet. Normal powder down is naturally coating the operculum, illustrating the need for showering.
Infraorbital Exploration and Trephination
Infraorbital sinusitis is a common disease in pet birds. This may lead to rhinitis, conjunctivitis, lacrimal infections, and if left untreated, may result in abscess and necrosis of the infraorbital sinus and osteomyelitis of the surrounding bone. Clinical signs include sneezing, nasal discharge, picking at the nares and choana with the toes, inflation of the infraorbital sinus, periorbital swelling and conjunctivitis. Hypovitaminosis A, low environmental humidity and environmental inhalant irritants may predispose birds to secondary bacterial and fungal infections. A sinus flush with sterile, non-bacteriostatic saline may be performed to obtain samples for cytology, and bacterial and fungal cultures [1,9,71]. If flushing of the sinus via the nares and other medical therapy (e.g., nebulization) is not effective in establishing drainage, a surgical approach may be used.
To access the infraorbital sinus, the patient is placed in dorsal recumbency and ophthalmic lubricating ointment applied to both eyes. An incision is initiated at the rostral aspect of the infraorbital diverticulum of the infraorbital sinus midway between the eye and the external nares. It is continued caudally, staying parallel with the lateral aspect of the head. Caution must be taken not to penetrate the ocular orbit located caudally. This area is extremely vascular and hemorrhage may be controlled by the use of a laser, radiosurgery, direct pressure or commercial hemostatic products. The sinus must be thoroughly explored, as mucoid, purulent or caseous material may be located within the nasal cavity, within the beak, and between the sinus and the nasal cavity caudal to the turbinates. The sinus cavity should be well irrigated with sterile saline prior to closure and it may be necessary to remove affected periorbital bone. Closure is achieved in a simple continuous pattern with monofilament suture [1,9,71].
Supraorbital trephination may be necessary to gain access to the dorsal and caudal areas of the infraorbital sinus, which cannot be accessed with nasal flushing and sinus aspiration. This will allow direct irrigation of these affected areas. The skin is incised to expose the frontal bone. Holes are made in the bone with a sterile rotary tool just above the eye. These holes are angled toward the midline. Cortical bone is removed until cancellous bone above the sinus is visible. Drilling is then advanced and widened to an appropriate diameter. Samples are obtained for cytology and culture, and the sinus irrigated with an appropriate solution such as saline, chlorhexidine, F10, water-soluble antibiotics and/or antifungals. The solution should pass through the choana and into the oral cavity to confirm that the trephination is accurately located. With this irrigation, fluid will enter the oral cavity; therefore, the patient should be intubated and the head positioned to allow the fluid to exit the mouth. To prevent aspiration, the oral cavity may be packed with an absorbent material to collect any excess fluid. The trephination site should be irrigated often and the site may need to be reopened, as healing occurs quickly. This procedure may be performed bilaterally, particularly in species such as passerines, in which the right and left infraorbital sinuses do not communicate. Once therapy is no longer required, the sites will heal quickly with minimal scarring [1,9,71].
Choanal atresia has been reported in African grey parrots (Psittacus erithacus erithacus) and one white cockatoo (Cacatua alba). The choana may either be entirely absent or there may be a membrane present that prevents communication between the nasal cavity and the pharynx. Rhinography and an endoscopic examination reveal this lack of communication [14,36a,71].
A choanal communication may be created with the nasal cavity by hand-drilling a 1/8- or 7/64-inch Steinmann pin into each naris, through the nasal choanae, to enter the choana. An 8 French red rubber catheter is then passed from one naris, through the choana, and exited through the other naris. Previously cut slits in the tubing allow mucus to drain. This creates a loop of rubber tubing across the cere with each end passing through the nares to the choana. The ends are tied and secured behind the head. The tube is left in place for 4 to 6 weeks to allow formation of a permanent communication. Nasal flushes with saline are performed twice daily for 7 to 10 days to prevent mucus from occluding the holes (Figs 35.15a-35.15n) [14,36a,71].
Figure 35.15a. An African grey with epiphora from choanal atresia. (Don Harris*).
Figure 35.15b. (From left to right) 0.065 K-wire, with or without the chuck, 3.5 French closed-end tomcat catheter, No. 5 French rubber feeding tube. (Don Harris*).
Figure 35.15c. To access the nasal passageway, the K-wire pin must be introduced in a direction perpendicular to the long axis of the head. The initial approach is the most important step, as it determines the site of choanal perforation. (Don Harris*).
Figure 35.15d. The tip of the pin (with or without the chuck) is introduced through the nostril beneath the turbinate. While maintaining contact with the ventral surface of the nasal cavity, the pin is angled medially until the ventral midline of the nasal cavity is encountered. The exact ventral midline must be located blindly - based on "feel." In birds that do not have an osseous blockage, the membrane can be determined by some "give" in the distal end of the pin as the midline is slowly approached. Or, instead of a soft membrane, you may encounter a "slot" in the bony tissue into which the pin tends to slip. At the midline of the ventral aspect of the nasal cavity, the pin is directed with minimal pressure and rotation to puncture through into the oral cavity.*
Figure 35.15e. When the perforation has been made, the K-wire is removed, and a tomcat catheter is inserted into the naris and passed in the same direction into the oral cavity. (Don Harris*).
Figure 35.15f. The tomcat catheter is introduced into the oral cavity with a hemostat which is used to pull it through the newly created opening. (Don Harris*).
Figure 35.15g. When the catheter has been pulled most of the way through, the proximal end must be trimmed to fit through the nasal passage. (Don Harris*).
Figure 35.15h. The distal end of the feeding tube is introduced into the proximal end of the catheter. (Don Harris*).
Figure 35.15i. A mark is made at the point where the two join together snugly. The feeding tube is removed and the catheter is trimmed at that point.
Figure 35.15j. After the connection has been made, the catheter is used to pull the feeding tube through the nasal perforation and into the oral cavity. (Don Harris*).
Figure 35.15k. After one end of the feeding tube is introduced into one nostril, the procedure is repeated by introducing the other end of the feeding tube into the other nostril. The free ends of the tube are pulled through so that the middle of the feeding tube is retracted onto the dorsal surface of the cere. (Don Harris*).
Figure 35.15l. At the point where the tube exits one nostril and enters the other, the tube itself must be trimmed to allow the passage of mucus from the nasal cavity externally. If this is not done, the sinuses fill with nasal mucus and the tube would need to be removed, drained and reinserted. (Don Harris*).
Figure 35.15m. The feeding tube actually creates a figure 8 configuration where one end enters the left nostril and comes out the right side of the mouth; the other end of the feeding tube enters the right nostril and exits the left side of the mouth. The ends are tied behind the bird’s head. (Don Harris*).
Figure 35.15n. A chin strap can be devised to help hold the tube in place. (Don Harris*).
Rupture of the Cervicocephalic Air Sac
Hyperinflation of the cervicocephalic air sac has been attributed to chronic infection and/or inflammation, while rupture may occur with trauma, with the former condition being more common. Location of the site of occlusion of normal air flow or rupture of the air sac in traumatic cases may not be identifiable. Smaller avian species typically suffer from generalized overinflation or rupture, while hyperinflation or subcutaneous emphysema is generally confined to the dorsum of the neck. A cutaneous Teflon stent may be surgically implanted at the highest point of the head to allow air to escape. The stent must be carefully monitored for occlusion with debris [1,9].
A skin incision is made just large enough to insert a 5- mm Teflon stent. Sutures are pre-placed in the four pairs of holes in the flange of the stent. The suture enters the one hole from the external side, doubles back, and passes through the other hole from the lateral side. Once all four sutures are placed, the stent is implanted. A 22-gauge needle is inserted through the skin at the proper location for one end of the suture material to be inserted through the needle to be exteriorized through the skin. This procedure is repeated for the remaining three sutures and the sutures tied in place. The stent may become occluded and may require cleaning with a swab or needle. Occasionally the cervicocephalic air sac may be so excessively hyperinflated that it may interfere with prehension of food or even traumatize the cornea. Excess redundant skin may require resection after releasing the excess air and deflating the air sac [1,9].
Placing a one-way valve connecting the cervicocephalic air sac to the clavicular air sac may also be used to treat rupture of the cervicocephalic air sac. An approach is made through the left lateral thoracic inlet. The tube is inserted into the hyperinflated air sac, directed caudally along the esophagus, through the thoracic inlet, and into the cranial aspect of the clavicular air sac. The tube is sutured to the longus coli muscle to prevent migration, but no attempt is made to suture the air sac around the tube. Skin closure is routine. This method does pose a risk associated with leaving a foreign object in the body. The risk/benefit ratio should be considered prior to surgery, as many birds function well with a persistently hyperinflated cervicocephalic air sac [1,9].
Air sac hyperinflation may be treated by an alternative procedure that may be used alone or in combination with those previously described. This procedure is particularly useful if the hyperinflated air sac poses a mechanical obstruction to respiration, food intake and physical movement. The air is removed by making a small incision in the overlying skin and air sac, thereby deflating and collapsing the air sac. Redundant skin and air sac are excised, and the skin and air sac sutured to the underlying tissue in several places to prevent extensive re-inflation. The surgical site is closed with a simple continuous pattern using monofilament suture. Traumatically induced subcutaneous emphysema may be alleviated by surgically incising the site to remove the excess air from under the skin.
Although postsurgical subcutaneous emphysema is possible, it is uncommon even in birds that have undergone extensive surgery to the air sacs and associated bone [1,9].
Foreign material such as seeds, granulomas, inflammation, scarring post-trauma, or concretions of epithelial cells and mucous may occlude the trachea or syrinx, resulting in respiratory distress. Clinical signs include respiratory distress, dyspnea and vocal change. A history of recent anesthesia and intubation should raise concern regarding iatrogenic tracheal trauma, particularly if the endotracheal tube cuff was inflated. Foreign material may be visible in the trachea by wetting the overlying feathers with alcohol and transilluminating the trachea. Often foreign material is located at the syrinx or main bronchi, and therefore may not be visible during an examination. The trachea also may be assessed and obstruction diagnosed with both radiographs and tracheoscopy [9,14,18,71].
Treatment varies with the severity of the disease, size of the patient and anatomy of the trachea. Certain species such as swans and cranes possess elongated, tortuous tracheas with portions being located within the thorax, making access to the distal trachea difficult. Emergency treatment includes oxygen supplementation and possible placement of an air sac cannula to create a patent airway and stabilize the patient prior to further care. Please refer to Chapter 7, Emergency and Critical Care for a complete description regarding placement of air sac cannulas in birds. An appropriately sized needle may be temporarily placed through the trachea just distal to the foreign body or granuloma to prevent distal migration of the obstructing material, particularly during endoscopic retrieval or debridement. In certain avian species, the pessulum, a midline syringeal cartilage, may be present, which may impede access to a syringeal or bronchial foreign body or granuloma [1,9,14,18,71].
Many foreign bodies may be retrieved and infectious or inflammatory granulomas may be debrided via tracheoscopy. This is an effective and minimally invasive procedure that should be pursued prior to tracheotomy. Establishment of a patent airway is necessary for respiration and anesthesia. An air sac cannula should be placed until the obstruction is removed. If the obstruction is due to a granuloma or inspissated material and mucus, a small tube such as a urinary catheter or an endotracheal tube may be advanced to the point of obstruction and used to attempt aspiration of the foreign material. Samples should be submitted for cytology, bacterial and fungal cultures. Appropriate antibiotics, antifungals, and nebulization should be continued postoperatively until resolution is achieved [1,9,18,71,84].
If unsuccessful, or if the patient’s trachea is too small to allow passage of an endoscope, a tracheotomy may be necessary. The patient is placed in dorsal recumbency and the area from the mandible to 1 to 2 cm distal to the thoracic inlet is surgically prepared. A transverse tracheotomy of approximately 50% of the tracheal circumference is performed on the ventral tracheal surface. The entire tracheal diameter should not be transected in order to maintain its anatomic alignment, reduce tension on the surgical closure and prevent disruption of the vascular supply. Stay sutures are placed around the tracheal rings adjacent to the tracheotomy site to atraumatically manipulate the trachea. Foreign material may be grasped and removed, gently debrided, suctioned, or material cranial to the incision may be pushed cranially to exit through the glottis. Simple interrupted sutures are preplaced to incorporate one to two tracheal rings on each end of the incision using small, absorbable monofilament suture. Knots are tied external to the tracheal lumen to prevent granuloma formation intratracheally. If the trachea completely separates during the procedure, an anastomosis may be performed in the same fashion, closing the entire circumference of the trachea. Soft tissue, subcutaneous and skin closures are routine (Figs 35.16a-35.16f) [1,6,7,9,14,18,71,84].
Figure 35.16a. Surgical preparation for tracheal surgery involves placing the patient in dorsal recumbency. The area from the mandible to 1 - 2 cm distal to the thoracic inlet is surgically prepared by removing the feathers and scrubbing the skin with an appropriate presurgical scrub. (Espen Odberg).
Figure 35.16b. A transverse tracheotomy incision is made on the ventral trachea, approximating 50% of the tracheal circumference. (Espen Odberg).
Figure 35.16c. Care should be taken not to exceed 50% of the tracheal circumference with the tracheotomy incision. This is critical in order to maintain anatomic alignment, reduce tension on the surgical closure and prevent disruption of the vascular supply. (Espen Odberg).
Figure 35.16d. A small-diameter endoscope can be inserted into the trachea to identify foreign material. (Espen Odberg).
Figure 35.16e. A small-diameter suction tip, feeding tube or endoscope can be inserted into the trachea and gentle suction applied to remove any aspirated material. (Espen Odberg).
Figure 35.16f. Simple interrupted sutures are pre-placed to incorporate one or two tracheal rings on each end of the incision using small, absorbable monofilament material. Knots are tied external to the tracheal lumen to prevent granuloma formation intratracheally. If the trachea completely separates during the procedure, an anastomosis may be performed in the same fashion, closing the entire circumference of the trachea. (Espen Odberg).
Due to the predilection of masses and foreign bodies to be located at the level of the syrinx, surgery is often focused on the thoracic inlet. An operating microscope or halogen-illuminated magnification head loupe is necessary for optimal visualization. The patient is positioned in dorsal recumbency and gas anesthesia is delivered via an air sac cannula. A sterile swab or feeding tube should be placed in the esophagus to facilitate identification and avoid iatrogenic trauma. The skin is incised from the right clavicular-sternal junction to the clavicular-coracoid junction just lateral and ventral to the crop. The overlying skin is gently elevated from the crop and the surrounding tissues bluntly dissected from the crop to avoid tearing the crop or transecting surrounding blood vessels. Once the crop is freed from its clavicular attachments it should be reflected to the left. The trachea is identified by its complete cartilaginous rings. The sternotracheal muscles traverse obliquely and are transected near their caudolateral tracheal attachments. A large blood vessel lies between the muscle bellies and should be coagulated prior to transection of the muscles [1,6,7,9,14,18,71,84].
Once access to the thoracic inlet has been achieved, it is helpful to elevate the cranial end of the restraint board to improve visualization deep into the thoracic inlet. The interclavicular air sac is bluntly dissected. A blunt hook is looped under the syrinx at the tracheal bifurcation and gently pulled cranially for better visualization. Tracheotomy, foreign body retrieval, granuloma debridement and closure are as described previously .
Certain species such as Amazon parrots, small macaws and smaller birds have shorter primary bronchi, and cranial retraction of the syrinx may result in avulsion of the bronchi from the lung. Therefore, a left lateral approach to the syrinx may be preferable. The patient is positioned in right lateral recumbency. An incision is made over the second and third ribs. These ribs are exposed by blunt dissection and transected at both ends to allow complete removal. This will expose the cranial portion of the lung. The cranial portion of the lung is gently dissected and reflected from its attachments with a moistened cotton-tipped applicator. The jugular vein, pulmonary artery and branches of the subclavian artery are then identified and should be avoided. Dissection between these vessels is performed to access the syrinx. A 2- to 3-mm incision is made in the syrinx using bipolar radiosurgical forceps at the junction with the left primary bronchus. A foreign body may be removed or granuloma debrided via tracheoscopy, suction or gentle manual removal. The syringeal incision heals by second intention. The lung is repositioned into its normal anatomic position and the ribs are not replaced. Soft tissue, subcutaneous and skin closure are routine [1,9,71].
Surgical removal of lung tissue is indicated for biopsy and for removal of abscesses, granulomas and primary lung neoplasia. Biopsy of lung tissue may be performed by endoscopy. This is an effective and less invasive procedure if the desired site for biopsy is accessible via laparoscopy. There is no discrete pleural space in birds and the visceral and parietal pleura are in close approximation. The dorsal pulmonary parenchyma is contoured tightly to the ribs and intercostal spaces, which facilitates the surgical approach. The avian lung is more vascular and the intrinsic clotting mechanism appears to be less efficient, as compared to mammals, therefore, hemorrhage is a concern [1,9].
The patient is placed in right or left lateral recumbency, depending on the site desired for biopsy, and the surgical area prepared routinely. A lateral celiotomy is performed. The lungs may be approached through the caudal thoracic air sac or through the intercostal space by removing one or two ribs. The affected lung tissue is carefully elevated using a sterile, moistened cotton tipped applicator and isolated using vascular or hemostatic clips. The tissue is excised between the clips, leaving them with the viable portion of the lung for hemostasis. No studies exist to determine the amount of lung tissue that may be safely removed or the physiologic effects of pneumonectomy. However, clinically, patients appear to recover well after partial pneumonectomy. Closure includes apposing the intact ribs with stainless steel suture, cerclage wire or non-absorbable monofilament suture. If a caudolateral thoracotomy has been performed and a portion of the last rib had to be removed for maximum exposure, resulting in unsuitable tissue to close the musculature, a stitch surrounding the remaining rib, passing caudally to and around the ipsilateral pubic bone can produce the tension needed to bring the tissues into apposition. Skin closure is routine [1,6,7,9].
Air Sac Granuloma Resection
Air sac granulomas are usually identified via radiographs, endoscopy or occasionally by ultrasound. If resection is indicated, a celiotomy is performed based on the relative location of the granuloma (see Celiotomy under Surgery of the Gastrointestinal Tract below).
Surgery of the Gastrointestinal Tract
Keratinized cysts, abscesses, oral papillomas, neoplastic masses and traumatically induced wounds may be found on the tongue, choana, glottis, submandibular cleft and salivary glands. Chronic vitamin A deficiency may result in the accumulation of keratin within cyst-like structures and the formation of caseous abscesses in the oral cavity, submandibular skin and salivary glands . These may interfere with respiration and swallowing. If respiration and food intake are not compromised, it may be beneficial to perform a fine needle aspirate to obtain samples for cytology, bacterial and fungal cultures. Appropriate antibiotic, antifungal and parenteral vitamin A therapy may reduce the size of the abscess and promote encapsulation, thereby reducing the size and vascularity of the mass to be removed. Medical treatment listed previously, including supplementation with beta-carotene, has occasionally been reported to resolve these abscesses [1,9,73].
Submandibular abscesses may be resected by incising the skin overlying the masses on the ventral neck. Abscesses within the oral cavity may be less accessible and extremely vascular. It is important to intubate these patients to prevent blood and debris from entering the airway, and pre- and postoperative endoscopic examination is helpful to fully assess the oral cavity and choana. Radiosurgery or laser may be used to incise the abscess and to control hemorrhage. The contents of the abscess are removed and the site irrigated with an appropriate disinfectant. If present, the capsule should also be resected if this can be accomplished without clinically significant hemorrhage. Samples are collected for cytology, histopathologic examination, bacterial and fungal cultures. The remaining defect is left to heal by second intention. Abscesses or cysts located on the palatine area and choanal slit may be removed in the same manner. This area is extremely vascular and hemostasis is crucial to prevent severe hemorrhage. Some surgeons recommend temporary ligation of the palatine arteries during the procedure [1,9,73].
Papillomatous masses may be removed from the choanal slit, glottis or pharynx with radiosurgery, laser or cryosurgery. Removal with chemical cauterization must be carefully controlled to prevent severe damage to adjacent tissues. Excision is usually not curative and recurrence is common. Papillomatous masses are often located in other regions of the gastrointestinal tract and cloaca. Hepatic and pancreatic carcinoma are associated with papillomatosis. The reader is referred to other sections of this text for a thorough description of papillomatosis and associated disease conditions (Fig 35.17a, Fig 35.17b, Fig 35.17c, Fig 35.18a, Fig 35.18b and Fig 35.18c) [1,9,73].
Traumatic injuries to the tongue may result in significant hemorrhage, pain and failure to eat. If topical anticoagulants and chemical cautery fail to control hemorrhage, a mattress suture may be placed with an absorbable monofilament suture. The knot of the ligature is placed on the ventral surface of the tongue .
Neoplasia of the tongue has been reported. These masses may be removed by radiosurgery or laser . Complete excision with adequate margins may be difficult and it may be beneficial to ablate the surrounding tissue. A feeding tube or frequent tube-feeding may be necessary for alimentation.
Figure 35.17a. A macaw with severe oral papillomatosis. The choanal slit is occluded with hypertrophic tissue, as is the majority of the oropharynx. (Espen Odberg).
Figure 35.17b. A loupe-monopolar radiosurgical tip can be used to debulk oral masses. Care must be taken not to damage adjacent tissues. (Espen Odberg).
Figure 35.17c. Silver nitrate can be used to debulk oral papillomas, but care must be taken not to cause chemical damage to adjacent structures within the oral cavity. (Espen Odberg).
Figure 35.18a. Papillomas may be found on the mucosal surface of the cloaca, oropharynx, esophagus/crop, proventriculus, ventriculus, bile ducts and pancreatic ducts. Cystic regression and recurrence is extremely common, and E. coli and Clostridium spp. are often isolated from the cloaca of affected birds. Surgical resection is recommended, particularly if the mass is causing straining to defecate, secondary cloacal infection, fecoliths, hematochezia, and cloacal prolapse. (Espen Odberg).
Figure 35.18b. Cloacal papillomas may be visualized by applying gentle pressure to either side of the vent. Insertion of lubricated cotton-tipped applications may aid in eversion of the cloacal mucosa and allow visualization of the prominent papillomatous tissue. Papillomas are identified by a characteristic "cobblestone" appearance of the mucosa. (Espen Odberg).
Figure 35.18c. Methods for removal of cloacal papillomas include silver nitrate cauterization, cryosurgery, radiocautery, laser surgery, and blade excision. The mass and affected cloacal wall may be everted manually and the mass debulked with any of these methods. If silver nitrate is used, as in this photo, the area must be thoroughly flushed with saline to prevent cauterization of normal mucosa as soon as sufficient tissue has been cauterized to debulk the mass. (Espen Odberg).
A pharyngostomy is most often performed in order to place a feeding tube. This is indicated if the patient is anorectic, or if it is necessary to bypass the oral cavity, the esophagus and/or the crop. The patient is placed in left lateral recumbency and the right side of the neck is surgically prepped from the caudal aspect of the mandible to the midcervical region. A small incision is made through the skin and the underlying esophagus is identified. A moistened cotton-tipped applicator or mosquito hemostat is inserted through the mouth and pharyngeal region and visualized through the skin. A small 1- to 2-mm incision is made over this swab in an avascular area. The tube is grasped with the ends of the mosquito hemostat to facilitate entry into the crop and advanced through the lower esophageal sphincter to the proventriculus, depending on the location of the pathology or disease condition that necessitated placement of the feeding tube. The external end of the tube is then sutured in place with two simple interrupted sutures, incorporating the skin and esophageal crop wall on both sides of the incision. The area is bandaged to protect the site, directing the external portion of the tube dorsally to prevent it being chewed or manipulated by the patient. When no longer needed, the sutures are cut and the tube removed. The esophagus/crop and skin can be left to heal by second intention [1,9]. A step-by-step pharyngostomy is shown in (Figs 35.19a-35.19g); the procedural details are similar to those used in other species.
Pharyngostomy - step by step Figs 35.19a-gFigure 35.19a. The length of the tube to be used is determined by measuring from the crop to the level of the proventriculus. (Scott Echols).
Figure 35.19b. The skin over the crop is incised. (Scott Echols).
Figure 35.19c. The crop tissue is exteriorized and incised just enough to allow tube insertion. (Scott Echols).
Figure 35.19d. The tube is placed in the crop and slowly advanced toward the thoracic inlet just ventral to the trachea. The surgeon’s index finger guides the tube within the esophagus, using the trachea as a guide, advancing into the thoracic esophagus and proventriculus. (Scott Echols).
Figure 35.19e. The tube is positioned for suturing. (Scott Echols).
Figure 35.19f. A purse-string suture is placed around the tube to prevent crop contents from leaking. (Scott Echols).
Figure 35.19g. The tube is coiled alongside the head. A bandage is applied that allows syringe access, but prevents the bird from pulling or scratching out the tube. (Scott Echols).
Esophageal perforation may be caused by the use of a firm feeding tube, struggling of the patient during tube feeding, enthusiastic feeding response while a feeding tube is inserted into the crop, or thermal burns followed by necrosis with or without fistulation. Food may enter the subcutaneous space through the lacerated or necrotic esophagus. Severe edema, infection, sepsis, toxemia and necrosis may result. Rapid emergency and supportive care must be instituted. Surgical repair will vary according to the extent of tissue damage, necrosis and infection (see Chapter 14, Evaluating and Treating the Gastrointestinal System, Fig 14.12a,b, Fig 14.12c, Fig 14.12d, Fig 14.12e and Fig 14.12f). The patient is placed in dorsal or lateral recumbency, depending on the location of the tissue damage, and repositioning may be necessary to gain access to all affected areas. A skin incision is made through the overlying skin with a blade, monopolar or bipolar radiosurgery, or with a laser. The subcutaneous and underlying esophagus is then examined to determine the extent of disease. If affected tissues appear healthy, immediate debridement, irrigation and closure may be possible. However, often these patients are diagnosed days to weeks after the initial perforation occurred and severe necrosis and infection are present. These patients may require multiple debridements and irrigation procedures. The external affected area should be bandaged with hydrophilic dressing to promote tissue granulation. Final surgical closure must be delayed until the necrotic tissue has been delineated and resected. Once this is achieved, the esophagus may be closed in a simple continuous inverting pattern, and the subcutaneous and skin closure is routine. A pharyngostomy tube may be placed extending through the lower esophageal sphincter to bypass the esophagus during feeding until the esophagus is healed [1,9].
Crop Burn Repair
Thermal crop damage with or without fistula formation may occur when overheated juvenile feeding formula is stored within the crop immediately after feeding. These thermal burns may range from minor and inapparent to severe and life threatening. The extent of tissue injury and necrosis may not be evident for several days to weeks. An attempt at immediate surgical repair may fail due to progressive tissue necrosis. With severe or extensive crop burns, the patient is often both septic and toxic.
Despite aggressive medical therapy, some of the patients will succumb within the first hours to days following presentation. Patients in this condition are not surgical candidates. Therefore, topical treatment, hydrophilic bandaging and supportive care are indicated. If a fistula occurs prior to delineation of the affected area and the establishment of a granulation bed, it is important to initiate supportive care. A pharyngostomy tube must be placed if the fistula is large enough as not to allow any appreciable food storage or if weight loss is documented. Otherwise the bandage covering the region may assist in containing the formula [1,9]. Medical treatment alone may resolve less severe burns, with shrinkage of the scar tissue closing the potential deficit. When the fistulated area has begun to granulate, then surgical repair should be performed [1,9].
The patient is anesthetized and placed in dorsal or lateral recumbency, depending on the location of the fistula. The area and surrounding skin are prepared aseptically. Do not use alcohol, as it may gain access to the esophagus and damage the serosa. A circumferential incision is made around the edges of the fistula and the adhered skin is separated from the ingluvies by blunt dissection. Care should be taken not to extend the fistula more than is necessary for removal of necrotic tissue. Placement of a tube or swab into the esophagus from the oral cavity will aid in the delineation of the crop. It is important to note that the skin is normally attached to the crop by two layers of striated muscle that form a sling-like support for the diverticulum of the crop. Once the crop is separated from the skin, the crop is closed in a simple continuous inverting pattern and the overlying skin closed in a simple continuous pattern. The skin and crop should be closed in two separate layers, as there is an increased risk of dehiscence if the two layers are closed together (Figs 35.20a-35.20e) [1,9].
Crop Burn Repair - Step by Step Figs 35.20a-e
Figure 35.20a. A severe crop burn that has been allowed several days to granulate. With the initial edema gone, the tissue layers can be more easily identified and separated for repair (6x). (Greg J. Harrison).
Figure 35.20b. The necrotic skin and the anterior wall of the crop have been removed in the scab (6x). (Greg J. Harrison).
Figure 35.20c. Scissors are used to cut the granulated union of the skin and the crop into separate layers (6x). (Greg J. Harrison).
Figure 35.20d. Trimming of devitalized or granulated tissue (6x). (Greg J. Harrison).
Figure 35.20e. A simple interrupted inverting suture pattern is used to close the crop (6x). (Greg J. Harrison).
Occasionally thermal burns are so severe that very little viable tissue remains. The length of the crop should be maintained if possible. Esophageal strictures are more likely to develop if resection and anastomosis are performed than if only a thin strip of esophageal tissue is preserved and allowed to granulate over a stent. If enough viable tissue is present, it may be sutured over a pharyngostomy tube. A longitudinal incision with a transverse closure will increase the diameter of the esophagus and may reduce the risk of esophageal stenosis. The patient must receive frequent small feedings of a soft or liquid diet until the crop stretches and the holding capacity increases. If there is not enough viable esophageal tissue present to close the defect, it may be allowed to heal by second intention while a pharyngostomy tube is in place. Alternatively, a dermoplasty may be performed once healthy granulation tissue is present. A rotating skin flap will usually cover the defect [1,9].
Ingluviotomy and Crop Biopsy
Pet birds, particularly neonates, are susceptible to ingestion of foreign materials. Feeding tubes, substrate and small toys are commonly ingested. The foreign materials will obstruct food passage and irritate the crop. Small objects may be retrieved from the crop by esophagoscopy or by manual retropulsion and withdrawal with a hemostat or tissue forceps. Manual retropulsion is noninvasive, but may result in inadvertent concurrent retropulsion and subsequent aspiration of liquid from the crop. Care must be taken not to damage the crop, esophagus, pharynx, oral cavity and choana, and a thorough examination of all structures should be performed after retrieving the object to note any trauma or remaining pieces of material. An endoscopic exam of the oral cavity, choana, pharynx, esophagus and crop after removal of foreign substance is useful to determine if there is any damage to these structures [1,9].
Indications for an ingluviotomy include foreign body retrieval, endoscopic access to the proventriculus and ventriculus, or biopsy of the crop for histopathologic evaluation. The patient is placed in dorsal recumbency and skin prepped routinely. It is important that the patient be intubated and, if there are contents within the crop, it is recommended to occlude the upper esophagus with a moistened gauze sponge to prevent any refluxed ingesta from entering the airway. An incision is made through the skin over the left lateral portion of the crop. This may be performed by scalpel, monopolar or bipolar radiosurgery, or with a laser unit. The skin is bluntly dissected to identify the crop. Stay sutures are placed in the crop wall to assist in manipulation of the crop, facilitate incising the crop and to prevent uncontrolled exit of material within the crop. The crop is then incised at the cranial aspect of the left lateral side of the sac. This area of the crop is less prone to stress as the crop fills and is not within the path of a feeding tube should the patient require tube-feeding postoperatively. This crop incision should be made with a scalpel blade or sharp scissors to preserve the integrity of small blood vessels. Radiosurgery should be used only to coagulate vessels. If the ingluviotomy is being performed for foreign body retrieval or for access to the proventriculus and ventriculus for an endoscopic exam, the incision into the crop should be performed in a relatively avascular region to control hemorrhage. If the purpose is to collect a biopsy of the crop for histopathologic examination - such as those performed as part of a diagnostic workup in patients demonstrating clinical signs consistent with proventricular dilatation disease- this biopsy should be collected from a vascular region, as it is crucial to collect nerve tissue that typically can be found in close proximity to blood vessels. Closure of the crop is accomplished with a simple continuous pattern oversewn with an inverting pattern with an absorbable monofilament suture on an atraumatic needle. Skin closure is routine (Figs 35.21a-35.21h) [22,25,57].
Ingluviotomy - Step by Step Fig 35.21a-h
Figure 35.21a. Cadaver showing a cotton-tipped applicator coming up the esophagus into the crop and the delicate nature and transparency of the crop’s tissues. (Greg J. Harrison).
Figure 35.21b. Distended crops may occur with primary disorders or lower gastrointestinal dysfunction. (Espen Odberg).
Figure 35.21c. An incision is made through the skin over the crop using a monopolar or bipolar radiosurgery unit or a laser. (Espen Odberg).
Figure 35.21d. The crop has been incised in this picture revealing a large amount of seed and other material within the crop lumen. (Espen Odberg).
Figure 35.21e. The seed and fibrous foreign material present within the crop have been removed. Fibers from a rug had formed a matrix for a bezoar in this bird. (Espen Odberg).
Figure 35.21f. Closure of the crop is performed with an interrupted suture pattern using an absorbable monofilament suture and an atraumatic needle. The needle pictured here is a cutting needle (vs an atraumatic needle) and is very large for use in the crop, thus increasing the risk of trauma and tearing of the tissues. (Espen Odberg).
Figure 35.21g. Once the incision is closed, saline should be injected into the crop, as pictured, or infused via gavage tube in order to identify any areas that are not completely sealed. If leaks are noted, additional sutures should be placed and the patency checked again. It is important to aspirate the fluid from the crop and keep the head elevated to prevent aspiration during anesthesia recovery. (Espen Odberg).
Figure 35.21h. Skin closure after an ingluviotomy. (Espen Odberg).
Esophageal Stricture Correction
Esophageal strictures may develop as a result of previous infection (trichomoniasis, capillariasis, candidiasis), trauma from tube-feeding, thermal or caustic burns, ingestion of a foreign body or secondary to iatrogenic surgical trauma. Therefore, once an esophageal stricture is diagnosed, the underlying etiology must be determined and addressed. It may be necessary to place a pharyngostomy tube for alimentation. The stricture may be resolved by passing a series of tubes of increasing diameter through the oral cavity and esophagus past the stricture over a period of several weeks .
There are several surgical approaches to the avian coelom. These include the left lateral, right lateral, ventral midline, and cranial, mid and caudal transverse approaches. Skin incisions vary with the surgical procedure and amount of coelomic exposure required. The surgeon should evaluate the skin and subcutaneous tissues overlying the surgical site for any sign of trauma, fatty infiltration, infection and necrosis. The surgical approach should maximize exposure of the coelomic organs, but minimize the involvement of diseased skin and subcutaneous tissues. For any celiotomy, the cranial part of the patient should be elevated between 30 to 40° to prevent fluids used for irrigation, or coelomic fluid, from flowing craniad and entering the respiratory tract following penetration of the air sacs. If coelomic fluid is present, as much should be aspirated as possible or surgery delayed until the fluid is resorbed. If coelomic fluid is aspirated while the patient is anesthetized, it may be necessary to adjust the vaporizer setting as the air sacs are allowed to completely expand and anesthetic gas concentration increases [1,9].
The left lateral celiotomy provides the best exposure to the proventriculus, ventriculus, female reproductive tract, left testicle, spleen, left kidney and the left ureter. The patient is placed in right lateral recumbency and the site surgically prepped. The caudodorsal border of the sternum is palpated, and the pelvic bones including the cranial pubis are identified. The left leg may be retracted caudally, creating a fold from the knee to the lateral margin of the sternum (knee web) to increase exposure to the cranial coelom (Figs 35.22a-35.22h). Alternatively, the leg may be retracted cranially to increase surgical exposure to the caudal coelom (Figs 35.22i-35.22p). Lung tissue can be visualized percutaneously between the fifth through seventh ribs in smaller birds. The latissimus dorsi and iliotibialis cranialis muscles obscure visualization of lung tissue in larger species. The skin is incised using monopolar or bipolar radiosurgery or with a laser from the cranial to caudal left paralumbar region. At the cranial edge of the knee web, just caudal to the last rib, the incision is continued caudoventrally to pass through the groove of the groin web to the region of the pubic bone. Once the skin incision is complete, the left leg may be further retracted caudodorsally to expose the abdominal wall. A branch of the superficial medial femoral artery and vein, visible passing over the lumbar fossa toward the pubis, should be cauterized. The abdominal wall incision is initiated in the external abdominal oblique muscle, just caudal to the last rib. This incision is extended caudally through the internal abdominal oblique and transverses abdominis muscles to the cranial aspect of the pubis [1,9,25,78].
Left Lateral Celiotomy - Step by Step Figs 35.22a-p
Figure 35.22a. Left lateral celiotomy with the left leg retracted caudally is the best approach for hysterectomy, ovary, adrenal, anterior kidney or testicular investigations. (Scott Echols).
Figure 35.22b. Site is plucked, surgically prepared and draped. (Scott Echols).
Figure 35.22c. Close-up view of draped site. (Scott Echols).
Figure 35.22d. Finger identifying the anterior border of the iliotibialis cranialis muscle, just caudal to the last rib. This is the paralumbar fossa. (Scott Echols).
Figure 35.22e. The incision is made in the middle of the paralumbar fossa. (Scott Echols).
Figure 35.22f. The last rib is identified and elevated. (Scott Echols).
Figure 35.22g. The last two ribs are transected. (Scott Echols).
Figure 35.22h. A retractor is in place to maximize visualization. (Scott Echols).
Figure 35.22i. Left lateral celiotomy with the left leg pulled anterior. This allows the ideal approach for the proventriculus, ventriculus, spleen, liver and caudal intestine tissues for surgical exploration. (Scott Echols).
Figure 35.22j. Area plucked free of feathers. (Scott Echols).
Figure 35.22k. Site of entry and associated structure locations. (Scott Echols).
Figure 35.22l. Site of entry and associated structure locations. (Scott Echols).
Figure 35.22m. Site of entry and associated structure locations. (Scott Echols).
Figure 35.22n. Site of entry and associated structure locations. (Scott Echols).
Figure 35.22o. Retractor in place. (Scott Echols).
Figure 35.22p. Exploration of the coelom anterior to the ventriculus. (Scott Echols).
In order to achieve adequate exposure to the cranial coelom, the last one to two ribs may be transected. The intercostal blood vessels course along the cranial edge of each rib and require ligation or coagulation. In small birds, these vessels may be coagulated by inserting the indifferent electrode of the bipolar radiosurgical forceps inside the thoracic wall, lightly apposing the electrodes at the cranial edge of the rib and then activating the electrodes. In larger species, it is recommended to clamp these vessel cranial to the ribs, transect the ribs and then apply a hemostatic clip to the respective vessel. Occasionally it is necessary, particularly in larger birds, to transect the last two ribs dorsally and ventrally and remove this section of the rib entirely [1,9,25,42].
Retraction of the abdominal wall may be maintained by a Heiss, Alm, mini-Balfour or Lone Star retractor. Retraction in smaller patients such as budgerigars may be achieved by gently applying a Halstead or Hartman mosquito forceps to the skin flap. This will avoid hemorrhage that may occur with retractors that penetrate tissue. Alternatively, ophthalmic lid retractors may be used. As the caudal thoracic air sac is entered, the caudal aspect of the lung is visible, including the ostium of the bronchi entering the abdominal air sac. The liver is noted ventrally and the proventriculus dorsally. If the abdominal air sac is entered, the lung will lie dorsolaterally. The intestines are apparent and may be gently manipulated with a moistened cotton-tipped applicator, ring-tipped ophthalmic forceps or microvascular surgical forceps. Toothed forceps traumatize intestinal tissue and may cause perforation. The proventriculus is located medially and is suspended by air sacs and suspensory ligaments. The intestines may be retracted caudally and ventrally to reveal the left kidney located dorsomedially in the coelom. The ovary or left testicle is visible at the cranial edge of the kidney and the adrenal gland noted between the gonad and the cranial division of the kidney. Obesity and organomegaly may alter anatomic location and obscure visualization of certain organs [1,9,42].
Transected ribs are not surgically reattached during closure, but left in the correct anatomic location surrounded by soft tissues. If the seventh and eighth ribs have been removed, tension-relieving sutures must be placed from the abdominal musculature to the sixth rib. The abdominal musculature is closed with absorbable monofilament suture in a simple interrupted or continuous pattern. Skin closure is routine [1,9].
A ventral midline, transverse or combination approach to celiotomy provides surgical access to the middle and both sides of the coelomic cavity. These approaches provide access to the small intestine, pancreas, liver, testes, oviduct (when enlarged) and cloaca [1,9,24].
The patient is positioned in dorsal recumbency and the site surgically prepared. Most avian species have a relatively large superficial vein located subcutaneously on the ventral abdomen. This vein may be coagulated prior to incising the abdominal wall to prevent hemorrhage. The skin is incised on the ventral midline from the caudal sternum to the interpubic space. The linea alba is identified and tented upward midway between the caudal sternum and interpubic space. It is then carefully incised with bipolar radiosurgical forceps, and the surgeon may inspect the underlying tissue for adhesions or other attachments to the peritoneum. If adhesions to the abdominal wall are noted or strongly suspected, the coelomic cavity may be evaluated with the use of an endoscope prior to extending the incision. These adhesions may be broken down with the use of a cotton tipped applicator or other blunt instrument. If adhesions cannot be broken down, an alternative surgical approach may be necessary. The incision is extended cranially and caudally by inserting the indifferent electrode under the linea alba, apposing the tips with the linea in between them and initiating the current while dragging the forceps cranially and caudally. This will incise the abdominal wall while preventing any hemorrhage. Extreme caution must be practiced not to extend this incision too deeply to prevent iatrogenic trauma and laceration to the duodenum and pancreas, which lie from left to right just inside the abdominal wall [1,9,24].
A transverse and ventral combination celiotomy may be performed to increase exposure to the
coelomic cavity. An incision may be performed in the cranial region (5 - 7 mm from the caudal border of the sternum), midabdomen or caudal region (5 - 7 mm from the cranial border of the pubic region). Care must be taken when making a caudal transverse incision, as intestinal loops often lie just under and may be attached to the abdominal musculature. A transverse incision is performed on one or both lateral sides caudal to the sternum, leaving sufficient tissue caudal to the sternum to allow subsequent closure. The size of the incision should be large enough to provide adequate exposure, but small enough to minimize escape of anesthetic gas and minimize hypothermia. Please refer to Chapter 33, Updates in Anesthesia and Monitoring for a discussion regarding anesthetic considerations for the avian patient during a celiotomy. The abdominal wall is closed using a simple continuous or interrupted pattern with an absorbable monofilament suture. Skin closure is routine [1,25,57].
Proventriculotomy and Ventriculotomy
Proventriculotomy is indicated for the removal of foreign or toxic material from the proventriculus or ventriculus if endoscopic retrieval is unsuccessful or impossible [1,9,42,78]. The patient is positioned in right lateral recumbency. A left lateral celiotomy is performed to provide the best exposure to the proventriculus and ventriculus. The ventral suspensory structures must be dissected bluntly to retract the proventriculus caudally. Stay sutures are placed in the wall of the ventriculus to exteriorize and manipulate both structures. The proventriculus is fragile and may tear or bruise if manipulated with toothed forceps or if stay sutures are placed in this organ. Certain atraumatic microsurgical instruments may be used to manipulate the proventriculus. The coelomic cavity should be packed with moist gauze sponges to prevent gastric contents from leaking into the coelom and assist in minimizing escape of anesthetic gas [1,9,42].
The proventriculotomy is initiated at the isthmus (junction of the proventriculus and ventriculus) with scissors. This incision is extended into the body of the proventriculus. Hemorrhage from the cut surface of the proventriculus is controlled by radiocautery. Proventricular contents and foreign material may be removed by suction or with a small curette. The lumen should be well irrigated after foreign body removal, and an endoscope may be used to perform an examination of the proventriculus prior to closure to ensure that all material has been successfully removed. The proventriculus is closed using a simple continuous pattern oversewn with a continuous inverting pattern using a fine, absorbable monofilament suture with an atraumatic needle. The inverting pattern should extend beyond the incision on both ends and the integrity of the closure evaluated with the injection of sterile saline. Abdominal wall and skin closure are routine [1,9,42].
Postoperative fasting is not necessary and the patient should be offered food and water once completely recovered. The strength of the incision is strongest immediately postoperatively and during the fibroblastic stage. Leakage of gastric contents is not an infrequent occurrence due to the lack of omentum in birds. If the proventricular wall appears thin or friable, it may be necessary to place a duodenal feeding tube for temporary alimentation. This will allow enteral alimentation of the patient while bypassing the proventricular incision during healing (Figs 35.23a-35.23k) [1,9,42].
The ventriculus may be accessed either through a proventriculotomy incision or through the ventriculus itself. The ventriculus is extremely vascular with heavy musculature in psittacine species, and healing postoperatively can be prolonged. Therefore, access to the ventriculus through the previously described proventricular incision is preferred when possible. The incision is initiated at the isthmus and extended into the ventriculus. The entrance into the ventriculus may be gently dilated to insert instruments to remove any foreign material, apply suction and irrigate the lumen. The ventriculus may be assessed with an endoscope to ensure complete removal of any foreign material.
An alternate approach to the ventriculus is through a cranial transverse celiotomy just caudal to the sternum. The ventriculus is identified and gently rotated clockwise to expose the thinnest portion of the ventricular wall. A longitudinal incision is performed with monopolar radiosurgery through the ventricular wall to access the luminal contents. The incision is typically 1 cm in length in a 400-g bird. Material may be removed with an appropriately sized spatula or curette. Foreign material may be removed from the proventriculus as well. The incision is closed using a horizontal mattress pattern with a slowly absorbable or non-absorbable monofilament suture. Care should be taken that the ventricular lumen is not penetrated during closure [1,9,42].
The serosal surface of the proventriculus or ventriculus also may be biopsied when evaluating a patient for proventricular dilatation disease. It is important to biopsy a vascular region to ensure that the surgeon has obtained nervous tissue. Abdominal wall and skin closure are routine [1,9,42].
Figure 35.23a-d. Approaching the proventriculus to free it for a proventriculotomy. (Scott Echols).
Figure 35.23e-g. Attaching suture to the muscular tissues of the proventricular-ventricular junction and freeing the proventriculus from surrounding attachments to allow exteriorization for the organ entry. (Scott Echols).
Figure 35.23h-j. Access to the lumen of the proventriculus and removal of contents and metal object noted on radiograph. (Scott Echols).
Figure 35.23k. Proventricular closure. (Scott Echols).
Intestinal Resection/Repair/Anastomosis Surgery
Intestinal surgery may be indicated in the following presentations:
- Obstructions, either from foreign bodies or secondary to adhesions or scarring.
- Intestinal neoplasia.
- Undiagnosed intestinal disease requiring biopsy.
- Traumatic incidents, often involving bite wounds from predator species.
- Congenital herniation and strangulation.
- Repair of iatrogenic damage to the intestine occurring during celiotomy.
The patient is placed in dorsal recumbency and a midline or transverse celiotomy is performed. The vascular supply to the small intestine is via the celiac artery to the duodenum and the cranial mesenteric artery to the jejunum and ileum. Any necrotic bowel is resected gently using microsurgical instruments to prevent damage to healthy intestinal tissue. An anastomosis is performed using a 6 - 0 to 10 - 0 absorbable monofilament suture on a one-fourth-circle atraumatic needle. Typically six to eight simple interrupted sutures are necessary for end-to-end anastomosis. Abdominal wall and skin closure are routine [1,9,25,42].
Enteral feeding tubes may be placed in the duodenum. This is indicated if it is necessary to bypass a diseased portion of the alimentary system. The patient is placed in dorsal recumbency and a midline or transverse celiotomy is performed. An indwelling jugular catheter, no less than one-third the diameter of the small intestine, is placed through the left abdominal wall and into the descending duodenal loop. The catheter is then advanced gently through the descending and ascending duodenal loops and the needle withdrawn from the intestine and abdominal wall. One to two sutures are placed with 5 - 0 monofilament in the intestine and abdominal wall to secure the intestine to the body wall and provide a tight seal. The patency and seal of the catheter is tested by injecting sterile saline solution and the celiotomy is closed routinely. The external portion of the catheter is secured using monofilament suture. The excess catheter is coiled and secured to the patient anterior to the leg and under the wing. An appropriate type and amount of a liquid diet is used to aliment the patient [1,9,25,42]. Hyperosmotic diets may cause an osmotic diarrhea. The amount to be fed should be divided into equal volumes and injected 4 to 6 times daily at a rate of approximately 1 ml/15 seconds to allow the intestine to accommodate for the volume. The catheter should be flushed with warm water or lactated Ringer’s solution before and after injecting the food to prevent obstruction of the catheter [1,9].
The patient and surgical site must be monitored closely for leakage and coelomitis, and for damage to the catheter and/or the incision site. Once the catheter is no longer needed, the suture is cut, the catheter removed and the incision is left to heal by second intention [1,9,25].
Surgery of the Reproductive Tract
Anatomy of the Female Reproductive Tract
The avian oviduct is divided into five anatomic regions, which are microscopically distinguishable (see Chapter 18, Evaluating and Treating the Reproductive System).
The avian oviduct is suspended via the dorsal and ventral ligaments within the coelomic cavity. The cranial, middle and caudal oviductal arteries run through the dorsal mesentery vascular supply to the oviduct. Species variations exist, but in general the cranial oviductal artery arises from the left cranial renal artery, aorta or external iliac artery. The middle oviductal artery arises from the left internal iliac artery or the pudendal artery. Venous blood from the cranial oviduct enters into the caudal vena cava via the common iliac vein and venous blood from the caudal oviduct enters the renal portal or hepatic system [24,43,45,59] (see Chapter 7, Emergency and Critical Care Fig 7.16, Fig 7.17, Fig 7.18 and Fig 7.19).
Ovocentesis and Manual Egg Delivery
Egg binding and dystocia occur in many pet bird species. If medical therapy fails to deliver the egg, ovocentesis or manual delivery may be attempted prior to a celiotomy. The clinician should be prepared to perform a celiotomy when attempting ovocentesis or manual delivery, as retropulsion of the egg and oviductal rupture, resulting in an ectopic egg, shell fragments or yolk coelomitis, are potential complications. A celiotomy with or without salpingohysterectomy may, in some cases, be a more rapid and effective method of resolving dystocia (see Chapter 7, Emergency and Critical Care Fig 7.16, Fig 7.17, Fig 7.18 and Fig 7.19).
Salpingohysterectomy involves removal of the oviduct. Salpingohysterectomy is indicated to prevent egg production, resolve disease conditions associated with egg production, infectious/inflammatory disease of the oviduct, oviductal neoplasia, oviductal torsion, oviductal prolapse, and weakening or herniation of the abdominal wall secondary to chronic reproductive activity [3,9,24,34,51,76]. It is not typically performed as a preventive procedure due to possible risks, namely hemorrhage, to the patient during the procedure. However, techniques such as endoscopic salpingohysterectomy in juvenile cockatiels have been described as preventive procedures for removal of the oviduct in juvenile birds . During sexual and egg-laying activities, the oviduct is hypertrophied and blood supply to the ovary and oviduct is significant. It is recommended to delay surgery if possible until the reproductive tract is in an inactive state, thereby reducing the risk of hemorrhage to the patient. Egg production may be stopped, and ovarian and oviductal size and vascularity may be reduced by medical therapy prior to surgery. Please refer to Chapter 18, Evaluating and Treating the Reproductive System for a complete description of medical therapy to reduce egg production [1,9,24].
The size and condition of the oviduct varies with the reproductive and physiologic state of the patient. Birds suffering from previous reproductive disease, particularly coelomitis, may have significant adhesions, which complicate surgical removal of the oviduct. These may include adhesions between the oviduct and the kidney, the cloaca and other coelomic structures. Caution must be taken when separating these adhesions, as hemorrhage and tearing of the affected tissue may occur. A hormonal feedback loop presumably exists between the uterus and the ovary to control follicular development and ovulation. In many birds following salpingohysterectomy, follicles will develop but will not progress to ovulation. However, some birds, namely Anseriformes, will develop large follicles and ovulate freely into the coelom. These ova may be resorbed without incident, but some birds will develop coelomitis. Clients should be informed of this potential and medical therapy to control ovulation, ovariectomy or cryosurgery of the ovary may be considered in these patients [9,24,43].
For salpingohysterectomy, the patient may be placed in right lateral recumbency and a left lateral celiotomy is performed. Alternatively, the patient may be placed in dorsal recumbency and a ventral midline celiotomy with or without a midabdominal transverse incision may be performed [9,24,49]. The ovary is visible at the cranial pole of the left kidney, adjacent to the adrenal gland. It may be necessary to retract the proventriculus and ventriculus ventrolaterally to improve exposure of the oviduct. The convoluted oviduct lies along the dorsal body wall in proximity to the caudal vena cava. The ventral ligament, responsible for these oviductal convolutions, courses caudally and becomes a muscular cord at the vagina. This ligament is dissected with bipolar radiosurgery to allow the oviduct to be released and positioned in a linear fashion [1,9,76].
The fimbria of the funnel portion of the infundibulum lies caudal to the ovary and is elevated to expose the dorsal attachments. The dorsal ligament that suspends the uterus and a branch of the ovarian artery course(s) caudally along the uterus from the base of the infundibulum. A small blood vessel is identified from the ovary through the infundibulum and is coagulated and transected with bipolar radiosurgical forceps or ligated with a hemostatic clip. If it is accidentally transected without coagulation, it retracts dorsal to the ovary and is irretrievable. Manual pressure and application of a small piece of absorbent gelatin sponge or beaded polysaccharide powder may be used to achieve hemostasis. The remaining suspensory tissue may be dissected with bipolar radiosurgical forceps [1,9,24].
The oviduct is retracted ventrocaudally once the infundibulum is free. This exposes the dorsal suspensory ligament, several small blood vessels and branches of the ovarian artery, which should be coagulated or ligated with hemostatic clips. As the dissection is continued caudally toward the cloaca, the ureter is identified as a white, tubular structure extending from the kidney to the cloaca. The ureter courses along the terminal colon and enters the cloaca, and should be identified and avoided. The uterus is ligated at its junction with the cloaca with hemostatic clips, using caution not to trap the left ureter (Figs 35.24a-35.24j) [1,9,24].
Alternatively, if the oviduct does not contain any infectious material, two hemostatic clips may be placed at the mid-magnum region and the tissue between them transected. This results in the removal of two shorter sections. The cranial portion is retracted ventrally and bipolar radiosurgical forceps are used to coagulate vessels and transect the oviductal ligament, thereby freeing the cranial oviductal section from the dorsal body wall and facilitating its removal. Once the cranial portion is removed, the caudal portion is retracted ventrally and bipolar radiosurgical forceps are used to coagulate vessels and transect the oviductal attachments caudally toward the cloaca. The ureter is identified and avoided. A hemostatic clip or ligature is applied at the junction of the uterus and cloaca, avoiding the ureter, and the uterus is transected with radiosurgical forceps or scissors and removed. It is important to ligate the entire circumference of the uterus to prevent any postoperative reflux and leakage of feces and urates from the cloaca into the coelom. Closure is routine and previously described. Samples are collected for cytology, bacterial culture and histopathologic examination, when indicated [1,9,24].
Salpingohysterectomy via Left Lateral Celiotomy - Step by Step Figs 35.24a-j
Figure 35.24a. From the left lateral approach with the leg caudal, the bird will undergo a salpingohysterectomy. (Scott Echols).
Figure 35.24b. Opening the confluent wall of the air sacs and the suspensory tissues of the proventriculus to allow entry into the hepatoperitoneal cavity. (Scott Echols).
Figure 35.24cf. Identifying and exteriorizing uterine tissues for a salpingohysterectomy and/or ovary removal. The use of cotton-tipped applicators allows the very fragile uterus to be manipulated. The blood supply comes from the dorsal aspect of the salpinx and uterus, or from vessels via the ovarian or cloacal areas. Exteriorizing the body of the uterus and transecting it, allows the maximum visualization of the vessels and surrounding tissue that must not be traumatized. Bisecting a large uterus as shown in the lower example can simplify exteriorization. (Scott Echols).
Figure 35.24g-j. Hemostatic clips are applied to the portion of the uterus that attaches to the cloaca. The uterus can then be transected and removed. The anterior vessels from the uterine ligament are ligated with hemoclips in a similar manner (Sealing these vessels with radio current alone is not sufficient). If hemostasis is not achieved in a rapid and thorough manner, the accurate placement of oxidized regenerated cellulose mesh may be required. Closure is routine. Some birds (especially budgies) have very thin paralumbar musculature and sutures tend to tear easily. Including the medial tissues of the thigh and encircling a rib with suture and then a layer of the cellulose mesh to fill the deficit has worked in such cases. Topical and systemic analgesics are needed. (Scott Echols).
Caesarean Section/oviductal Sparing Celiotomy
It is often recommended that a salpingohysterectomy be performed when a celiotomy is necessary for reproductive problems such as removal of an egg that is bound. However, it may be necessary to salvage the reproductive capabilities of some avian patients. In addition, it may be prudent in some patients to initially remove the problematic egg without performing a hysterectomy, employ medical therapy to reduce the size and vascularity of the oviduct, and perform a salpingohysterectomy at a later time. The surgical approach varies with the location of the egg. If located cranially, a left lateral celiotomy is recommended, and if caudally located, a ventral midline approach with or without a transverse incision provides optimal exposure. The oviduct is incised directly over the egg, avoiding obvious blood vessels, and the egg removed. The oviduct is examined for gross abnormalities and samples are collected for cytology, bacterial culture and histopathologic examination. The oviduct is closed with a simple interrupted or continuous pattern using an absorbable monofilament suture. An inverting pattern is not recommended since this may reduce the oviductal luminal diameter. Abdominal and skin closure are routine. It is recommended to rest the hen from reproductive stimuli for a minimum of 2 to 4 weeks and if possible for the remainder of the reproductive season or longer, based on culture and histopathologic results. It is crucial to identify and correct the etiology that initiated dystocia prior to resuming breeding .
Removal of the Ovary and Ovarian Biopsy
Partial or complete ovariectomy may be indicated in patients that suffer from ovarian neoplasia, ovarian granulomas, persistent follicular activity, oophoritis and ovarian cysts that do not resolve with medical therapy. It is a challenging procedure and often poses great risk to the patient. Due to this risk, medical alternatives including hormonal manipulation and intralesional chemotherapeutic administration should be explored. It also is important to note that none of these procedures have been satisfactorily studied in pet birds. Laparoscopic ovarian biopsy is generally preferred. Hemorrhage is a significant potential complication and the clinician should be prepared to perform an emergency celiotomy during the laparoscopic procedure [1,24,57].
The avian ovary is attached to the cranial kidney and the dorsal body wall by the mesovarian ligament and receives its blood supply from the ovarian artery, which originates from the left cranial renal artery or directly from the aorta. Accessory ovarian arteries also may arise from adjacent arteries. The ovarian artery further divides into many branches, with the greatest blood flow directed to any large preovulatory follicles that are present. Ovarian veins join to form the main anterior and posterior veins that drain into the overlying vena cava. Multiple left ovarian veins may be present and drain into the cranial oviductal vein. Venous blood then enters the common iliac vein and finally the vena cava. The cranial oviductal vein may be too short or too poorly developed to identify. Multiple short veins appear to enter the common iliac vein over the length the dorsal base of the ovary [24,34,43,45,59].
The ovary is tightly adhered to its dorsal attachments. This makes complete excision of the ovary extremely difficult and poses significant risk of hemorrhage to the patient. The avian ovary is attached to the cranial renal artery by a short stalk and the attachment to the common iliac vein is intimate and extensive. Life-threatening hemorrhage often occurs from a lacerated common iliac vein during ovariectomy .
Ovariectomy and salpingohysterectomy may be attempted in the juvenile bird as an effort to prevent future reproductive disease. Ovariectomy has been described in many poultry studies. Unfortunately, most articles poorly elucidate the exact technique or associated complications [52,66,70,81,86]. Any of these procedures still pose significant risk to the hen, and clients should be well counseled regarding the potential for hemorrhage and complications. A ball-tipped electrocautery probe may be used to coagulate ovarian follicles of immature hens. However, this procedure results in ovarian regeneration in mature hens. A procedure to remove the ovary of juvenile hens includes manually removing the ovary in toto. The caudal end of the ovary is grasped with angled hemostats and pulled gently in a cranial direction with clear separation from the dorsally located common iliac vein. When performing this procedure it is important to stop immediately if any resistance occurs to prevent tearing of the overlying vein [9,24].
Ovariectomy in the adult hen must include removing ovarian follicles or cysts, debulking the mass of the ovary and then removing the ovary just ventral to its blood supply. The patient is placed in right lateral recumbency and a left lateral celiotomy is performed. Any large preovulatory follicles are either manually debulked or aspirated. Blood-filled follicles may represent previously ruptured blood vessels from an invasive mass and caution must be taken when removing these to prevent hemorrhage. Ovarian cysts should be aspirated. When aspirating follicles or cysts, a small (23 - 25 gauge) butterfly catheter may be inserted into the most avascular region to prevent hemorrhage and the contents aspirated. Care must be taken not to spill aspirated contents, particularly in conditions such as oophoritis, which could result in development of infectious coelomitis. Once follicles and/or cysts have been removed or aspirated and collapsed, the ovarian surface is visible and prepared for debulking. Leakage of cystic contents does not typically result in coelomitis in non-infectious conditions .
An angled DeBakey neonatal vascular clamp is applied dorsal to the ovary to occlude the vascular supply. This clamp is atraumatic, remains in the surgical site without obstructing the surgeon’s view and provides hemostasis. This clamp must be applied parallel to the spine to avoid entrapping the aorta and peripheral nerves. The ovarian tissue is excised with the use of a monopolar radiosurgical wire loop until very little tissue protrudes through the hemostatic clamp. The vascular hemostat is carefully opened, but left in place while the area is monitored for hemorrhage. If hemorrhage occurs the hemostat may be replaced. If possible, the vascular clamp is then opened, moved dorsally and reapplied to the ovarian base. This process is continued until the overlying vasculature is clearly visible and the course of the common iliac vein may be seen .
Once the bulk of the ovary has been removed, the vascular supply must be securely ligated and the remaining ovarian tissue excised. One to two hemostatic clips are applied dorsal to the vascular clamp with 90° clip applicators. It is recommended to apply the first clip in a caudal- cranial direction and the second clip in a cranial-caudal direction to incorporate the entire vascular supply. The remaining ovarian tissue is excised with the use of a monopolar radiosurgical wire loop. Another procedure may be pursued if the ovarian attachment to the common iliac vein is too extensive to apply hemoclips, or if there is erosion into the overlying vessel, as with some invasive ovarian neoplasia. The common iliac vein is ligated with a hemoclip just caudal to the ovary and cranial to its junction with the caudal renal vein. When performed properly, the ovarian artery and common iliac veins are effectively clamped. This allows the surgeon to carefully dissect the ovarian tissue from the overlying vessels. If necessary, the ventral wall of the common iliac vein may be safely removed. It is important to note that there is a significant risk of damaging the left adrenal gland, significantly altering blood flow through the renal portal system and the cranial renal division, and damaging the overlying kidney and lumbar and/or sacral nerve plexus. Closure is routine and the patient must be monitored for postoperative hemorrhage [9,24].
There are reports of carbon dioxide laser ablation and cryosurgical destruction of the ovary and neoplastic tissue (R. Wagner, personal communication, 2003). These techniques may allow for more complete removal of ovarian tissue and less risk of hemorrhage, however, ablation must be strictly controlled to prevent damage to the adrenal gland, vascular supply to the left kidney and local nerves. Removal of avian gonads with laser often resulted in severe hemorrhage intra- and postoperatively .
Anatomy of the Male Reproductive System
The male avian reproductive system includes the testes, the epididymis and the ductus deferens. The testes are located just ventral to the cranial division of the kidneys and are connected to the dorsal body wall by the mesorchium. The epididymis is located at the testicular hilus at the dorsomedial aspect of the testes, and continues caudally lateral to the ureter and terminates at the urodeum as papillae ventral to the ureteral ostium. The testicular artery arises from the cranial renal artery and provides most of the arterial blood supply to the testes. Budgerigars and passerines have a seminal glomus at the distal ductus deferens that forms a prominent projection and serves for sperm storage. There may be an accessory artery that arises directly from the aorta. Venous blood either returns directly to the vena cava or forms a common vessel with the adrenal veins. Testicular vasculature may vary among avian species or individuals [24,46,48,59].
Orchidectomy and Testicular Biopsy
Indications for orchidectomy include testicular neoplasia, testicular cysts, and infectious and inflammatory conditions of the testicle(s) that are unresponsive to medical therapy [1,9,24,30,83]. Laparoscopy is the preferred method for testicular biopsy [15-17].
Castration techniques have included simple extraction in chickens (caponization), laser ablation, intravascular suction and complete surgical excision. Testicular regrowth is extremely common unless the entire testicle is completely removed. Removal of testicles carries significant risk of hemorrhage and should not be used in place of behavioral therapy, environmental manipulation, or exogenous hormone therapy for testosterone-related behavioral disease. In addition, castrated Gamble’s and scaled quail maintained ornate breeding plumage and exhibited overt aggression, demonstrating that these behaviors were either learned or resulted from the influence of hormones other than testicular-produced testosterone [24,60].
Medical therapy is instituted prior to surgery to reduce the size of active testicles. Several surgical approaches have been described. The patient may be placed in dorsal recumbency and a ventral midline celiotomy with or without a transverse flap is performed. This provides access to both the left and right testicles if both are to be removed. Alternatively, a lateral celiotomy may be performed to gain access to either the left or right testicle. It is possible to access the opposite testicle from a lateral incision by incising the midline junction of the corresponding air sacs [9,24].
The testicle is gently retracted ventrally and a 90° vascular hemostat or hemostatic clip is applied to the base of one testicle with 90° clip applicators incorporating its vascular supply. The hemostat or clip must be applied parallel to the spine to avoid entrapping the aorta and peripheral nerves. If possible, a second clip is applied just ventral to the first. One clip is applied in a craniocaudal direction and the second clip in a caudal-cranial direction to incorporate the entire vascular supply. The base of the testicle is incised between the hemostat or clip and the ventrally applied clips with a scalpel blade, scissors or radiosurgery. Alternatively, the testicular tissue may be debrided with the use of a monopolar radiosurgical wire loop or excised with scissors until very little tissue protrudes through the hemostatic clips. The vascular hemostat is carefully opened, but left in place while the area is monitored for hemorrhage. If hemorrhage occurs the hemostat may be replaced and another hemostatic clip applied dorsal to the previous clips, or if hemorrhage is minor a small piece of hemostatic gelatin sponge or beaded polysaccharide powder may be placed over the area. Any remaining testicular tissue that protrudes through the hemostatic clip may be ablated with electrocautery or a laser. Residual testicular tissue may result in tissue hyperplasia and produce reproductive hormones. Closure is routine and the patient must be monitored for postoperative hemorrhage [9,24].
Indications for vasectomy in birds include providing "teaser males" and to control reproduction. This procedure is not typically performed in pet birds. In the budgerigar, the patient is placed in dorsal recumbency and a 3- to 7-mm incision is made lateral to the cloacal sphincter. The fat and abdominal musculature is carefully dissected to enter the coelomic cavity. An operating microscope is used to locate the ductus deferens and a 5-mm section of the ductus deferens is excised. The skin is closed routinely. It is recommended to repeat the procedure on the other side 2 weeks later [24,77].
In the finch, a 3-mm incision is made 5 mm lateral to the cloaca with the use of an operating microscope. The fat and abdominal musculature is incised to access the seminal glomera. The ductus deferens is carefully separated from the ureter and one or more sections excised without ligation. The skin is closed routinely [11,24].
Vasectomy in larger avian patients is performed via transection of the ductus deferens via lateral or transverse celiotomy or laparoscopy. This procedure has been described in Japanese quail (Coturnix japonica). During a laparoscopic approach, the patient is placed in right or left lateral recumbency and the leg pulled cranially. A laparoscope is inserted at the apex of an inverted V created by the semitendinosus muscle as it passes over the last rib. The testis and ductus deferens are identified and distinguished from the kidney, adrenal gland, ureter and common iliac vein. The proximal ductus deferens is isolated and grasped with biopsy forceps. This section of the ductus deferens is transected and removed through the biopsy sheath. Care must be taken not to damage the ureter and common iliac vein. Closure is routine. The patient is repositioned on the contralateral side and the procedure repeated [24,44].
Cloacal Prolapse Repair
Cloacal surgery is indicated in those patients suffering from prolapse of the cloaca for removal of cloacoliths, and for cloacal papilloma debridement. Old World psittacines, particularly cockatoos, may develop intermittent or permanent prolapse of the cloaca. Reduced sphincter tone, chronic masturbation and straining, and chronic bacterial cloacitis have been implicated as causes for this disease. A thorough history and medical evaluation often elicits the cause. Medical therapy may include appropriate antibiotics based on cytology and bacterial culture and sensitivity and counseling clients to create a non-reproductive environment [1,9,24].
If unresponsive to medical therapy, surgical intervention may be necessary to prevent the cloaca from prolapsing. Minor prolapse may be resolved by placing temporary mattress sutures on both sides of the vent or by placing two transverse sutures across the vent. Sutures should not be placed in the vent itself due to potential damage to the innervation. Purse-string suture of the vent is contraindicated due to frequent postoperative cloacal atony. Any procedure involving the surgical fixation of the cloacal wall to the abdominal musculature or ribs will interfere with the normal physiologic movement during voiding and egg laying, and may result in significant discomfort to the patient [1,9,24].
Occasionally, cloacal prolapse is due to or results in atony of the vent sphincter. Narrowing the diameter of the vent or performing a ventplasty may treat this condition. This may be accomplished by one of two procedures. Two triangular-shaped wedges are excised from the superficial surfaces of each side of the vent, without traumatizing the muscular or nervous tissue. This creates a reduction in the vent opening by one-third to one-fourth. Simple interrupted sutures are placed with monofilament nylon through the skin and subcuticular tissues. Another procedure to accomplish reduction of the vent opening includes incising one-half to threefourths of the margin of the circumference of the vent to provide a cut surface for healing. Simple interrupted sutures are placed from one side of the vent to the other to partially close the vent opening, thereby preventing prolapse of the cloaca [1,9,24] (Figs 35.25a-35.25l).
Prolapsed Cloacal Repair - Vent Resection and Reduction - Step by Step Figs 35.25a-l
Figure 35.25af. Prolapsed cloaca is currently considered a malnutritional and/or behavioral disorder. Until corrections for such problems become effective, the prolapses need to be replaced and maintained with some surgical method. Cloacopexy has been used for years, but often proves insufficient for long term treatment. Ventplasty is used to reduce the diameter of the orifice. A thin, superficial dermal layer is removed (c-i) and a routine closure is made. Appropriate space must be maintained to allow passing of droppings but retention of tissues. Over-closing results in retention of droppings. Adjusting the opening in such a case should occur within a matter of hours. Such surgery is often done in cockatoos (notorious self-mutilators) and devices applied to the neck to avoid mutilation are advised, as are pain medicines both systemically and topically. (Scott Echols).
Figure 35.25g-l. Prolapsed cloaca is currently considered a malnutritional and/or behavioral disorder. Until corrections for such problems become effective, the prolapses need to be replaced and maintained with some surgical method. Cloacopexy has been used for years, but often proves insufficient for long term treatment. Ventplasty is used to reduce the diameter of the orifice. A thin, superficial dermal layer is removed (c-i) and a routine closure is made. Appropriate space must be maintained to allow passing of droppings but retention of tissues. Over-closing results in retention of droppings. Adjusting the opening in such a case should occur within a matter of hours. Such surgery is often done in cockatoos (notorious self-mutilators) and devices applied to the neck to avoid mutilation are advised, as are pain medicines both systemically and topically. (Scott Echols).
Current theory attributes cloacal prolapse, in many cases, to behavioral and/or nutritional causes. In the interim, however, surgical reduction of cloacal prolapse may be required. Cloacopexy, following various techniques (see text) tends to be a temporary fix at best, unless underlying causes are addressed.
A percutaneous cloacopexy may be performed. This may offer only a temporary resolution, but it is much less invasive than the more extensive procedures later described. (Ed. Note: With behavioral modification and hormonal manipulation, many practitioners are finding the need for more invasive cloacopexy unnecessary. The percutaneous technique has, in these editors’ experience, supplied sufficient support to allow for the institution of medical and environmental therapy).
The patient is placed in dorsal recumbency and the abdomen surgically prepared from the caudal sternum to the pubis. The prolapsed tissue is replaced manually or with a lubricated cotton-tipped applicator or gloved lubricated index finger. The applicator may be left in the cloaca to delineate the location of the ventral cloacal wall, or finger or appropriately sized syringe case may be inserted into the cloaca. Two to three percutaneous sutures are placed using monofilament nylon while the intracloacal object gently holds the ventral cloacal wall against the abdominal wall. This aids in displacing intracoelomic organs so as not to entrap them in between the abdominal and cloacal walls. Potential complications include entrapment or perforation of the ureters, rectum, duodenum and pancreas. This is avoided if the suture placement is restricted to the ventral aspect of the body wall, directly lateral to the linea alba. It is important to note that any surgery that places the cloaca in a fixed position will interfere with the dynamic action of the cloaca during defecation and micturition [1,9,24].
Birds with chronic cloacal prolapse often have elongated the distal colon from constant straining and subsequent protrusion from the vent. Therefore, although care is taken to remain ventral in the placement of the cloacopexy sutures, this distended colon may be forced to make a "U" turn when the ventral cloaca is sutured too extensively in a cranial direction. This can result in folding of the colon on itself and a functional colonic obstruction. If fecal material is not produced within a reasonable period of time post-cloacopexy, the veterinarian should consider removal of the most cranial abnormal cloacopexy suture.
A circumcostal or rib cloacopexy may be performed in patients suffering from severe cloacal prolapse. The patient is placed in dorsal recumbency and a ventral midline celiotomy is performed. Placing a lubricated cotton tipped applicator, gloved finger, or syringe case will facilitate identification and manipulation of the cloaca. The cloacal wall is identified and bluntly dissected from the surrounding fat and subcutaneous tissues. Fat tissue on the ventral surface of the cloaca must be excised for a successful outcome. The ribs are pushed caudally while the abdominal incision is elevated manually. This will bring the ribs into view to facilitate suture placement. An absorbable monofilament suture material is passed around the last rib on the right and left sides. These sutures are then passed through the full thickness of the ventral aspect of the craniolateral extent of the urodeum. Large tissue sections must be used for suture placement and it appears to be necessary to penetrate the cloacal lumen. The sutures are tied with enough tension to slightly invert the vent. Several other sutures are then placed between the body and cloacal walls. The cloaca also may be sutured to the caudal border of the sternum instead of the ribs if excessive inverting tension is placed on the cloaca when sutured to the ribs. There may be increased discomfort associated with this surgical procedure when compared to others [9,24].
A third cloacopexy technique includes fixing the coprodeum to the abdominal wall. A 2-to 5-mm incision is made in the serosal surface of the coprodeum approximately 5 to 10 mm lateral to the ventral midline of both the right and left sides. Corresponding paramedian incisions are made in the peritoneal surface of the body wall cranial enough so as to result in slight inversion of the vent. Three to four absorbable monofilament sutures are placed in the serosal surfaces of the coprodeum and body wall so as to appose the subserosal surfaces .
An additional cloacopexy technique involves closure of a celiotomy incision to include the cloacal and body wall. The patient is placed in dorsal recumbency and a ventral midline celiotomy is performed. The cloaca is reduced and the lubricated cotton-tipped applicator left in the cloaca to aid in identification and manipulation of the cloaca. Fat is excised from the ventral cloacal surface. The abdomen is closed incorporating the cloacal wall. An absorbable monofilament suture is passed through one side of the body wall, through the full thickness of the cloaca and through the other side of the body wall in a simple interrupted pattern. The overlying skin is closed routinely. Performing the same procedure via a caudal transverse celiotomy approach offers similar benefits, but additionally it avoids incising the cloaca should a future ventral midline celiotomy be necessary .
Cloacal Mass Excision
Internal papillomatosis is reported in New World psittacine species including macaws, Amazon parrots, hawk-headed parrots and conures. Papillomas may be found on the mucosal surface of the cloaca, oropharynx, esophagus/crop, proventriculus, ventriculus, bile ducts and pancreatic ducts. Cystic regression and recurrence is extremely common and E. coli and Clostridium spp., are often isolated from the cloacas of affected birds. Surgical removal is recommended, particularly if the mass is causing secondary cloacal infection, fecaliths, hematochezia, cloacal prolapse or if the bird is straining to defecate, indicating a mechanical obstruction. In addition, cloacal leiomyosarcoma has been reported in a blue-fronted Amazon parrot (Amazona aestiva) [9,28,68].
Methods for removal of cloacal papillomas include silver nitrate cauterization, cryosurgery, radiocautery, laser surgery and excision with a scalpel. The mass and affected cloacal wall may be everted manually and the mass debulked with any of these methods. If silver nitrate is used, the area must be profusely flushed with saline to prevent cauterization of normal mucosa as soon as sufficient tissue has been cauterized to debulk the mass (Fig 35.18a, Fig 35.18b and Fig 35.18c) [1,9].
A cloacotomy may be performed to increase exposure to the affected mucosa and allow complete removal of a large occlusive mass. The patient is placed in dorsal recumbency and the abdomen surgically prepped from the caudal edge of the sternum to the vent. A ventral midline incision with or without a caudal transverse incision is made with a scalpel blade, scissors, radiosurgery or laser through the skin from the mid-abdomen to the ventral vent opening. The underlying vent sphincter muscle and the cloacal mucosa are incised with scissors to expose the entire cloaca. The mass may be removed with chemical cauterization, cryosurgery, radiocautery, laser surgery or excision with a scalpel. When chemical cauterization is used during a cloacotomy, extreme caution must be taken due to increased potential of damage to normal adjacent tissue. Hemorrhage may be controlled with radiocautery. The cloacal mucosa is apposed where the mass is excised with a small, absorbable monofilament suture in a simple continuous pattern. The cloacal mucosa is closed in a simple continuous pattern and the vent sphincter is apposed using a horizontal mattress pattern, both utilizing absorbable monofilament suture. The skin is closed in a simple continuous or interrupted pattern with a monofilament suture. An appropriate antibiotic should be used peri- and postoperatively. Surgical complications may include hemorrhage, scarring, stricture formation, fecal and urate retention, and incontinence [1,9,23].
Mucosal stripping has been reported in a lilac-crowned Amazon parrot (Amazona finschi) for removal of cloacal papillomas. Recurrence of the papilloma occurred at the mucosal border adjacent to the sphincter 4 weeks postoperatively and cloacal anatomy was severely disrupted. Significant pain, lethargy, prolonged recovery, weight loss, leukocytosis and stricture of the cloaca also occurred. Therefore, mucosal stripping is reserved for cases where extensive debulking, is necessary. This may need to be done in a stepwise fashion; resecting only a portion of the mucosa is less invasive .
Coelomitis may occur secondary to ectopic ovulation, inflammatory and infectious conditions of the gastrointestinal, respiratory and reproductive systems. Many patients will recover with medical therapy and those patients that do require surgical intervention may benefit from medical treatment and supportive care prior to surgery 12,13,31.
If appreciable coelomic fluid is present, it is recommended to either delay surgery or perform an abdominocentesis prior to surgery. Abdominocentesis, if performed, must be accomplished precisely on the ventral midline to prevent coelomic fluid from escaping from peritoneal cavities and gaining access to the respiratory system. This escape of peritoneal fluid into the air sacs also can occur during celiotomy. This may result in life threatening respiratory disease [9,24].
The patient is placed in dorsal recumbency with the head and cranial body slightly elevated. Coelomic fluid is aspirated as described above, if indicted a ventral midline celiotomy is performed. A ventral midline approach may avoid transection of the air sacs and any fluid may be suctioned or drained. It may be necessary to adjust the vaporizer setting, as anesthetic depth may be altered when depth of respiration changes. The intestines are retracted atraumatically to gain exposure to the reproductive tract and other coelomic organs. Yolk material and tissue debris are gently removed and the coelomic cavity examined for abnormalities including tissue adhesions . A salpingohysterectomy with or without ovariectomy should be performed to prevent future disease. There is risk of respiratory compromise to the patient if air sacs are transected and additional intracoelomic fluid accumulates postsurgically. There often are significant adhesions present between coelomic structures, particularly between the oviduct, and the kidney, ureter and the cloaca. Salpingohysterectomy requires breaking down these adhesions to allow excision of the oviduct. Tearing of these structures and hemorrhage are potential complications. Occasionally oviductal adhesions are too extensive to allow removal of the oviduct. Patients frequently have abdominal distension and muscular dysfunction postoperatively [9,24]. Some clinicians alleviate this by removing excess muscular tissue or by rolling the muscular tissue to create a muscular stent prior to closure of the coelomic cavity.
Miscellaneous Surgical Procedures
Limb amputation appears to be well tolerated by psittacines, however, emotional concerns of the owners often arise and may present a need for careful counseling by the surgeon prior to committing the bird to the surgery. When amputation is recommended not as a result of severe trauma to the bird, but rather due to neoplasia, nonunion fractures or chronic infection, the surgery may be postponed for 1 to 2 days to allow the owner time to reach a decision.
In cases of amputation due to neoplasia or infection, pre-operative radiographs are necessary to assure that affected bone, which may extend proximal to the visibly affected skin and soft tissue, is completely excised.
Prior to performing an amputation, the surgeon should make sure that the surgical team and equipment are prepared for the potentially life-threatening hemorrhage that can occur. At a minimum, a preoperative hematocrit and total protein should be performed to provide an indication of the overall health status of the patient. Extreme care must be taken in small avian patients and patients with a low hematocrit, as death can occur in these patients from the loss of a relatively small amount of blood. The use of a tourniquet is recommended as a means of controlling intraoperative hemorrhage during most amputations. Commercially available rubber small animal tourniquets have the potential for causing severe skin trauma. These types of tourniquets can be used if they are well padded. A soft nylon rope, 1/2" rolled gauze, rubber band held by a hemostat, or piece of thick (<1 - 0) catgut suture provide alternatives. An assistant is necessary to hold the ends of the rope or suture and control the amount of pressure exerted. Ideal pressure will occlude the blood flow to the distal portion of the limb without causing trauma to the skin and underlying tissue. If skin trauma is noted, the placement of the tourniquet must be altered. If it is determined preoperatively that a tourniquet is not to be used, then careful dissection and ligation of the blood vessels is necessary. This may significantly increase the length of the surgery, but is absolutely necessary to prevent hemorrhage. If a tourniquet is not initially applied, it should be kept readily available in the event of severe hemorrhage. Being able to rapidly apply a tourniquet intraoperatively may mean the difference between life and death for an avian patient .
Appropriate perioperative analgesia will significantly decrease the stress to the patient. If possible, it also is recommended that the avian patient be preconditioned to an Elizabethan collar or "sweater," which will prevent picking at the sutures of the amputation site until the skin is fully healed. Use of these devices and this period of adjustment are especially important for reducing the stress to the patient and decreasing postoperative complications The potential for hemorrhage makes prevention of postoperative picking at the skin and sutures critical.
Amputation of the Wing
When a wing amputation is performed, it is desirable to perform the surgery as distal as possible. This will allow retention of a portion of the normal function of the wing for balance. Some avian patients may traumatize the amputation site and a more proximal amputation site may be necessary. Wing amputation can be divided into three different categories: distal, mid-wing and proximal. A distal wing amputation can be defined as an amputation performed distal to the carpal joint. Indications for this surgery include inoperable neoplasia of the distal wing, severe trauma or chronic infection. These typically occur in small birds such as budgies, lovebirds or cockatiels, making the need for amputation not uncommon in these species [26,40].
Birds weighing less than 150 g should be anesthetized and placed in dorsal recumbency. The feathers distal to the carpal joint should be removed and the area aseptically prepared. Depending on the size of the bird, one or two hemostatic clips can be placed across the distal portion of the carpal joint firmly enough to crush the bone. The portion of the wing distal to the hemoclips can then be removed with a scissors leaving 5 mm of tissue. This small amount of tissue allows for the placement of skin sutures and provides tissue in the event of the hemoclip slipping. The incision is then closed with non-absorbable 5 - 0 monofilament suture with an atraumatic needle of equal size or smaller than the suture. The hemoclips can typically be removed in 2 to 6 weeks. Appropriate postoperative pain management is necessary. The bird should be observed carefully postoperatively to ensure that it is not picking at the hemoclips or sutures. If necessary, an Elizabethan or tube collar can be applied [5,9].
Mid-wing or elbow joint disarticulation is indicated for small to medium-sized birds with trauma, nonunion radial or ulnar fractures, neoplasia or infection of the distal third of the wing. By performing the amputation at this point, the bird will lose its ability to fly but will maintain the use of the wing for balance. The bird should be anesthetized and placed in lateral recumbency. If possible, the feathers 1 to 2 cm proximal and the feathers distal to the elbow joint should be removed and the skin aseptically prepared. A tourniquet can be applied at the level of the mid-humerus to decrease the risk of severe hemorrhage [9,20,40].
A circumferential skin incision is made distal to the elbow joint with a radiosurgical unit, laser or scalpel. Care must be taken to make the incision such that sufficient skin remains to allow closure of the incision. The insertion of the antebrachial muscles and related soft tissues are transected with radiosurgical forceps at the level of the elbow joint. The ligaments of the elbow are transected and the articular cartilage of the humeral condyles is carefully removed with rongeurs or scissors. Horizontal mattress sutures with an appropriately sized, absorbable monofilament suture are used to suture the muscle over the distal humerus. If large vessels are identified, they should be ligated with absorbable monofilament suture. The tourniquet is carefully loosened and the sutured tissue examined for any signs of hemorrhage. Hemostasis can be provided by coagulation with a bipolar radiosurgical forceps, identifying and ligating bleeding vessels, or applying very small hemoclips. The skin is closed in a horizontal mattress pattern with an appropriately sized, non-absorbable monofilament suture. Placing the suture deep into the muscle is desirable to prevent the possible formation of a hematoma postoperatively. The skin of the wing is very fragile and avoiding the formation of a hematoma may be difficult. It is important to provide postoperative pain management and an Elizabethan collar may be necessary to prevent picking at the incision .
A proximal or proximal-humeral amputation is indicated for chronic trauma to the distal wing, neoplasia, nonunion or open, severely contaminated fractures and severe infection. The bird will lose the ability to utilize its wing for balance, but most psittacines appear to be able to adjust to this without complications. The patient should be anesthetized and placed in dorsal recumbency. The feathers should be removed and the skin aseptically prepared. The distal portion of the wing can be wrapped or covered with appropriate surgical draping material. Application of a soft tourniquet significantly decreases the possibility of severe hemorrhage. The tourniquet should be placed on the proximal humerus. If a mid-humeral amputation is to be performed, the tourniquet should be placed around the shoulder joint, incorporating the insertion of the pectoral muscles. If a proximal humeral disarticulation is to be performed the tourniquet should be placed around the shoulder joint including the brachial plexus .
A circumferential incision at the mid-humerus is made using a radiosurgical unit, laser or scalpel. It is important to leave sufficient tissues to allow for closure of the skin. Also, it should be noted that despite the presence of a tourniquet, some hemorrhage may occur. Ligatures are placed around the distal portion of the muscles using appropriately sized, absorbable monofilament suture. The suture size should be based on the size of the bird and large enough that when tightened, there is compression without cutting of the tissue. The muscles are then transected at their musculotendinous junctions near the elbow joint using a radiosurgical unit. Blood vessels are identified and coagulated or ligated with 3 - 0 or 4 - 0 absorbable monofilament suture prior to being transected. The tourniquet should be loosened and any bleeding vessels ligated or coagulated with the radiosurgical unit. The muscles of the humerus are bluntly dissected from their tendinous attachments to the bone. The humerus is transected in the proximal third of the bone or, alternatively, the proximal humeral joint is disarticulated and the synovial tissues of the glenoid fossa are removed with appropriately sized rongeurs. The pneumatic nature of the proximal humerus makes good tissue coverage of the end of the bone very important. Inserting a piece of gelatin or collagen foam into the distal portion of the remaining bone will ensure that blood does not travel through the humerus into the rest of the respiratory system. Impregnating this material with an appropriate antibiotic may be useful in preventing or aiding in the treatment of soft tissue or bone infection. The muscles are then sutured over the stump using a horizontal mattress or simple interrupted pattern with 3 - 0 or 4 - 0 absorbable monofilament suture. The skin and subcutis are apposed using 3 - 0 or 4 - 0 nonabsorbable monofilament suture in a simple interrupted or horizontal mattress pattern. The incision site should be monitored carefully for postoperative hemorrhage. Due to the potential for hemorrhage through the pneumatic portion of the humerus, the patient should be observed carefully for signs of respiratory distress. This surgery can be very stressful to the avian patient and may necessitate several days of hospitalization postoperatively. As with all amputations, postoperative analgesics are imperative (Figs 35.26a-35.26g). Injection of a lidocaine derivative intraoperatively in the area of the radial nerve will also decrease postoperative pain [9,40].
Wing Amputation - Step by Step Figs 35.26a-g
Figure 35.26a. An aggressive tumor involving the carpus was an indication for wing amputation. Harrison prefers to amputate at a joint, thus the elbow was the chosen site. (Greg J. Harrison).
Figure 35.26b. The brachial vein is the first vessel encountered when amputating a wing at the elbow joint. Note the rubber band tourniquet that is secured by a hemostat. (Greg J. Harrison).
Figure 35.26c. The radiosurgery forceps are placed around the vessel and the coagulation setting is used to seal the vessel. (Greg J. Harrison).
Figure 35.26d. The cutting current is used to incise the vessel and surrounding tissue. (Greg J. Harrison).
Figure 35.26e. Vessels, ligaments and tendons are transected in a similar manner. Transection of muscle is avoided whenever possible. (Greg J. Harrison).
Figure 35.26f. If the upper wing is involved, the wing can be amputated at the proximal 1/3 of the humerus or at the shoulder joint. Larger diameter vessels in this area will require more extensive and careful ligation. Muscles will require transection, however, sufficient musculature should be retained to cover the remaining portion of humeral bone in the case of amputation at this level. If amputation is performed by disarticulation of the shoulder joint, muscle should be retained and sutured to fill the dead space and prevent seroma formation. (Greg J. Harrison).
Figure 35.26g. Skin closure after proximal wing amputation. (Espen Odberg).
Amputation of the Leg
Most companion avian species function well with only one leg, especially psittacines. Care must be taken when considering leg amputation in avian patients. If the leg is amputated distally, the avian patient will attempt to use the remaining stump for ambulation. Contraindications for leg amputation include obesity, osteoarthritis of the contralateral leg or if the bird is unable to utilize its wings to assist in balancing. It is important to provide appropriate perching material to allow ease of grip and prevent perch-associated pododermatitis postoperatively. Amputation is indicated in avian patients with severe non-union fractures, severely contaminated open fractures, neoplasia, severe trauma or infection of the distal leg. Because a large portion of the femur is located within the skin of the body wall, a midfemoral amputation provides for adequate tissue to cover the end of the bone, prevents self-mutilation and is cosmetically acceptable. In captive raptors, postoperative pododermatitis of the contralateral foot is a common sequela, however, it is rarely observed in psittacines fed an appropriate diet and supplied with appropriate perches [9,20,29,58,74].
The patient should be anesthetized, placed in dorsal or lateral recumbency, and the feathers removed from the ventral abdomen distally to the stifle joint. The skin is aseptically prepared utilizing a standard orthopedic technique. The skin incision is made with a radiosurgical bipolar forceps along the web of the knee in the contour of the abdomen and semicircular incisions are made at the level of the stifle. Sufficient skin must remain to provide for closure without undue tension. Ligatures are placed around the distal portion of the muscles using 1 - 0 or 2 - 0 absorbable monofilament suture. Blood vessels are identified and ligated with 3 - 0 or 4 - 0 absorbable monofilament suture prior to being transected. A periosteal elevator is utilized to elevate the muscles from the proximal femur to the mid diaphyseal region. A bone cutter, osteotome, Gigli wire or other instrument appropriate for the patient’s size is used to transect the femur. The muscles are then sutured over the stump with 3 - 0 or 4 - 0 absorbable monofilament suture in a simple interrupted or horizontal mattress pattern. The skin and subcutaneous tissues are apposed using 3 - 0 or 4 - 0 nonabsorbable monofilament suture in a horizontal mattress pattern. As with proximal humeral amputations, this surgery is very stressful for the avian patient and may necessitate several days in the hospital postoperatively. Appropriate pain management is imperative [9,58,74].
Amputation of the Digit
Toe amputation is indicated in the event of severe trauma, neoplasia, avascular necrosis or infection of any of the digits. The tissue damage may be so severe or multiple toes may be involved such that amputation of the distal portion of the foot is also required. The same surgical techniques are utilized for both the toes and the feet. The patient is anesthetized, placed in dorsal recumbency and the distal portion of the leg aseptically prepped. It should be noted that the avian patient may present to the hospital with a large amount of fecal material on their feet. This requires careful cleaning prior to surgery because of the added risk for contamination and infection of the surgical site. Appropriate postoperative antibiotic therapy is necessary [9,35].
It is possible to perform two types of digit amputations, a proximal joint disarticulation and a phalangeal middiaphyseal amputation. A tourniquet composed of a thick suture material or a soft nylon rope is applied to the mid-tibiotarsal bone to control hemorrhage for both procedures. The site of a joint disarticulation of a digit should be at the joint proximal to the affected area. The skin should be incised distal to the stump to allow for sufficient skin for closure. A bipolar radiosurgical unit or scalpel blade can be used to make parallel horizontal incisions on either side of the toe. Alternatively, an incision is made around the dorsal two-thirds of the toe. It is important not to incorporate the plantar aspect of the digit with this approach. The phalanx is amputated at the proximal end of the bone. The joint may be disarticulated utilizing rongeurs, a scalpel blade, laser or electrosurgical unit. Any exposed joint surface can be removed prior to skin closure. Close in a horizontal mattress pattern with appropriately sized (3 - 0 to 5 - 0), nonabsorbable monofilament suture. If a horizontal incision was made, the edges of the skin are apposed with the knot tied on the dorsal surface of the skin. If a plantar skin flap was created, the skin is sutured to cover the end of the bone. Placing the most dorsal suture initially will allow for symmetrical apposition of the sides. The thicker skin of the plantar surface of the toe will provide additional protection for the end of the bone [9,35].
A mid-diaphyseal amputation is generally performed on small avian species. The skin is cut proximal to the affected tissue in a circumferential manner utilizing a radiosurgical unit or scalpel blade. The skin is then carefully retracted, exposing the underlying bone. The diaphysis of the bone is transected using rongeurs or scissors. The skin is then pulled distally to cover the exposed bone. Sufficient tissue is removed from the dorsal portion of the remaining skin of the toe to create a flap of plantar skin that will cover the end of the bone. The skin is then sutured using 4 - 0 or 5 - 0 non-absorbable monofilament suture in a horizontal mattress pattern. The affected toe and incision should be monitored closely for postoperative signs of infection. An Elizabethan collar or bandaging of the foot, can be utilized to prevent picking at the incision postoperatively .
Abdominal Wall Hernia Repair
Abdominal wall hernias may be congenital or acquired. The etiology is undetermined, but several disease conditions have been implicated. Hyperestrogenism leading to weakening of the abdominal musculature has been suggested as a predisposing cause in budgerigars (Melopsittacus undulatus) and cockatiels (Nymphicus hollandicus). Chronically egg-laying hens and changes in calcium metabolism may contribute to muscular atony. Lack of exercise, malnutrition, obesity, space-occupying masses, organomegaly, trauma, or chronic masturbation and straining may result in weakening of the abdominal musculature and abdominal distension [9,50,53,56].
Most "abdominal hernias" in birds do not in fact have an opening in the aponeurosis of the abdominal muscles. A true hernia is defined as a protrusion of an organ through connective tissue or through the abdominal wall in which it is usually enclosed. Therefore, a thorough examination is crucial to accurately diagnose an abdominal hernia. Herniation may include separation of the aponeurosis of the abdominal musculature at the ventral midline, allowing coelomic viscera to displace outside the muscular body wall. Clinical signs may include disease associated with entrapment of intestinal loops. "False hernias" or abdominal distension requires investigation of primary etiologies, therefore, a thorough examination and diagnostic protocol is important to accurately assess the patient’s condition. In many patients, false hernias are of little clinical consequence and do not require surgery. In addition, surgical repair may carry significant risk. Respiratory compromise may result when reducing the coelomic contents due to increased pressure on the abdominal and thoracic air sacs. Herniorrhaphy is indicated if the abdomen is being traumatized due to distension causing abrasion or ulceration by contact with the perch or floor, herniation of coelomic viscera poses risk to the patient, secondary clinical disease such as egg binding, intestinal obstruction, cloacal urolithiasis or difficulty expressing urates develop. Abdominal hernia and distension have been associated with hepatic lipidosis, reproductive tract disease, intracoelomic lipomas and peritoneal cysts [9,50].
Pre-operative radiographs, with gastrointestinal contrast media if needed, will identify the location of structures within the distended or herniated abdomen.
The patient is placed in dorsal recumbency and a ventral midline or an elliptical incisional celiotomy is performed. Caution must be taken when making the midline incision to avoid iatrogenic trauma to underlying viscera. Herniated viscera are gently replaced and the hernia repaired while patient respiration is closely monitored. The distended abdominal wall is trimmed on either side of the linea alba to create a normal anatomic abdominal wall. The abdominal wall is then sutured in a simple interrupted or continuous pattern with absorbable monofilament suture and the overlying skin closed routinely. If the body wall defect is extremely large, a mesh implant may be considered for repair [1,9].
Abdominal Mass Excision or Biopsy
Surgical excision or biopsy of neoplastic masses is indicated for several different types of disease conditions. Removal often requires prolonged anesthesia, strict hemostasis and careful anatomic dissection. This predisposes the patient to hypothermia, hemorrhage and metabolic compromise. Surgical procedure varies with the organ affected. Laser surgery may show some promise for removal of neoplastic and granulomatous masses [3,9,51].
When a biopsy and histopathologic diagnosis are obtained, or when complete surgical resection carries an unacceptable risk, alternative treatments may be preferred. Recent advances in oncology, including intralesional cisplatin and carboplatin, have shown promise for various abdominal neoplasias (see Chapter 20, Overview of Tumors).
Lipomas are frequently the result of obesity. Some species demonstrate a predisposition to development of lipomas (see Chapter 13, Integument). Correction of malnutrition, obesity and increased activity level often will reduce the size of lipomas . Medical treatment including supplementation with L-carnitine, or levothyroxine if a hypothyroid condition has been accurately diagnosed, has not met with consistent results [19,75]. It is important to note that liposarcomas, leiomyosarcomas and other masses that mimic lipomas have been reported in pet psittacines .
Lipomas that are well encapsulated are generally simple to excise. However, large, diffuse or broader-based lipomas can pose a significant patient risk when excision is attempted. Occasionally, loss of adequate vascular supply will result in central necrosis and ulceration. Large abdominal lipomas may be prone to inadvertent trauma and damage to the overlying skin . The Cavitron ultrasonic surgical aspirator (CUSA) has been used to safely resect lipomas in budgerigars. This ultrasonically powered aspirator selectively fragments and aspirates parenchymal tissue while sparing vascular and ductal structures. Preliminary evaluation suggests that the CUSA may provide reduced tissue necrosis and hemorrhage, increased visibility, shortened operating and anesthetic duration, and reduced recovery time when compared to blade resection, bipolar cautery and CO2 laser excision .
Biopsy of the kidney may be performed through a lateral, ventral midline or combination ventral midlinetransverse celiotomy . In addition, a dorsal pelvic approach has been described . Renal biopsy may be performed via laparoscopy. The reader is referred to Chapter 24, Diagnostic Value of Endoscopy and Biopsy for a complete description of this procedure.
Products Mentioned in the Text
- a. Vascular clamps, Sontec Instruments, www.sontecinstruments.com
- b. Weck Hemoclips, Solvay Animal Health, Inc., Mendota Heights, MN, USA
- c. Gordon Laboratories, Upper Darby, PA, USA
- d. HemoBlock, Abbot Laboratories, North Chicago, IL, USA
- e. Silverglide Nonstick, Select-Sutter, Germany
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Affiliation of the authors at the time of publication
1Hunt Valley Animal Hospital, Hunt Valley, MD, USA. 2AviVet, Oslo, Norway. 3The Bird Hospital, Greenacres, FL, USA. 4Underwood Animal Hospital, Heath, OH, USA.