Prostate disease includes hyperplasia, infection, cysts, abscesses, and cancer. Severe diseases of cysts, abscesses, and cancer are treated by excisional and partial prostatectomies. All prostatic disease, except cancer, can be prevented by castration during the first year of life. Castration, as a treatment of prostatic disease, reduces hyperplasia and the potential for persistent infections. Despite castration as a treatment for prostatic disease, prostatic abscesses can persist and present later as a clinical problem. When prostatic disease develops, castration is recommended in all patients except those with prostatic cancer. The terminal prognosis for prostatic cancer mandates an attempt to early diagnosis.

Prostatic abscesses and cysts are difficult to treat. Surgery is required, and treatment is frequently complicated by disease recurrence, incontinence, infection, sepsis, and even death. Treatments initially attempted for abscesses and cysts included extra-abdominal drainage by Penrose drains or marsupialization. Early complications of these drainage procedures included sepsis in one-third of patients and death in one-fifth. The remainder of these dogs had transient improvement, but abscessation recurred in nearly one-fifth and incontinence in one-fourth of the dogs. To reduce the postoperative complications associated with prostatic tissue as a septic focus and mediator of infection, excisional prostatectomy was performed to remove all prostatic tissue. Although excisional prostatectomy reduced the incidence of early postoperative sepsis and eliminated recurrence, over 90% of dogs with excised diseased prostates also developed incontinence.

I prefer to treat most patients with abscesses and cysts by castration and partial prostatectomy using an ultrasonic aspirator followed by omentalization. This technique eliminates nearly all the prostatic tissue while preserving the urethra and most nerves. Closed-suction drains have been successfully used to drain noninfected cysts, such as those with vascular and lymphatic drainage problems in perineal hernia. These dogs should be castrated. Many patients with abscesses and cysts appear to be adequately treated using peritoneal omentalization. All fluid-filled pockets must be explored and adequately drained. Before omentalization of paraprostatic cysts, the cysts should be excised as much as possible without damaging the urethra or the neurovascular supply.

Diagnosis

Diagnostic studies are designed to establish the anatomic distribution and histologic type of disease, to characterize the systemic response to the prostatic disease, to identify coexistent problems, to identify infections, and to characterize incontinence and outflow obstruction. The presenting complaints vary with the severity and type of disease. Tenesmus can be produced by any prostatic enlargement, that is, by hyperplasia, cyst, abscess, and neoplasia. Urethral obstruction is most typical of cancer, but it may occur in patients with cysts, abscesses, and hyperplasia. Incontinence is common in severe prostatic disease. Urethral discharge can be produced by nearly any prostatic disease with an opening into the prostatic urethra. Persistent urinary tract infections are frequently related to prostatic infections, particularly abscesses and infected cysts. Abdominal masses can be produced by cysts and abscesses. Many systemic responses develop in response to prostatic disease.

The size and character of the prostate should be determined by physical examination, including combined rectal and abdominal palpation, radiography, and ultrasonography. Contrast studies, especially retrograde urethrography, can be useful to identify the urethra, bladder, and prostate. Cystic structures as seen with an ultrasonogram have a more serious prognosis than hypertrophy, especially if a urinary tract infection is present. Cytologic and bacterial cultures can be obtained by sampling the urethral discharge, by semen ejaculation, by prostatic massage, by traumatic catheterization, or by direct sampling by needle aspiration or use of a larger biopsy needle. Placement of a needle into the prostate can be facilitated by ultrasonography or palpation. Care must be taken in placing a large-bore needle into a fluid-filled pocket of an infected prostate gland.

Most dogs with severe prostate disease do not urinate normally. Incontinence is common and frequently worsens after surgery. Even dogs that have undergone only a biopsy have dribbled urine after surgery, probably as a result of disease progression. Although obstruction in the absence of cancer is commonly thought to be infrequent, obstruction does occur and may be associated with calculi and strictures unrelated to cancer. Detrusor instability can develop in dogs with prostatic disease. A urethral pressure profile can identify decreased urethral pressures, which are common in dogs with prostatic disease, and a cys-tometrogram can identify an inability to develop a detrusor response or an irritable bladder. If incontinence persists after surgery, medical treatment can be attempted for each of these conditions.

Preoperative Care

Dogs with prostatic infections, especially those with abscesses, frequently become septic and develop toxic shock. Diagnosis is based on physical examination, urinalysis, complete blood and platelet counts, and serum chemistry profile, particularly liver enzymes, glucose, and albumin. Perioperative antibiotics must be given, preferably based on culture results. Although Escherichia coli is the most common organism isolated in bacterial prostatitis, some dogs have already been treated with long-term antibiotics and have developed resistant infections. Septic dogs, without culture results, are started on a combination of clindamycin and enrofloxacin. Measures to prevent and treat shock must be done and include fluid support, blockers of ischemia and reperfusion injury, and cardiotonic drugs (dopamine or dobutamine). Hypovolemia and hypotension must be treated by large volumes of intravenous fluids. If the albumin and total solids are low, plasma, hetastarch, or dextrans should be considered. Blockers have been used and included dexamethasone (2 mg/kg intravenously), flunixin (1 mg/kg intravenously), and deferoxamine (20 to 40 mg/ kg intramuscularly or slowly intravenously) but their efficacy remains controversial. Monitoring must include either indirect or direct arterial blood pressure. The anesthetic regimen should be based on the patient’s disease status. Finally, surgery must be both expeditious and accurate to reduce the spread of sepsis.

Surgical Techniques

Excisional Prostatectomy

Excisional prostatectomy is used to treat cancer. This treatment is usually palliative, but it can be effective in extending the patient’s normal life for several months because transitional and prostatic carcinomas usually grow slowly. Another treatment option for proximal urethral cancer is excision of the lower urinary tract and implantation of the ureters into the colon. This produces ascending renal infections. Dogs with neoplastic urethral obstruction can be successfully managed for months by a cystostomy tube. Neither medical therapy nor radiation treatment provides significant benefits in patients with prostatic cancer. Urethral stents can provide temporary relief of urethral obstruction. Prostatectomy also can successfully cure prostatic abscesses and cysts, but the high rate of incontinence makes this procedure less desirable than partial prostatectomy or peritoneal omentalization.

Incisional biopsies are done by cutting deeply into the prostatic gland and then placing deep mattress sutures into the capsule to produce hemostasis (Figure 32-1). The prostate is approached by a midline laparotomy (Figure 32-2A). The periprostatic fat is incised on the ventral midline and is reflected laterally (Figure 32-2B). An excisional prostatectomy requires dorsal dissection. Before prostatic surgery, a temporary tourniquet is placed about the distal aorta, just cranial to its bifurcation into the external iliac arteries. After placement of a urethral catheter, a retraction suture is placed around the urethra caudal to the prostate. Caudal dissection is facilitated by cranial incision of the ventral ligament of the penis. The prostate is rotated to ligate vessels close to the prostatic capsule and to ligate the vas deferens. The surgeon attempts to preserve the caudal vesical artery bilaterally and to preserve much of the urethra, both on the side of the neck and distally. Prostate tissue or fluid should be cultured. Multiple biopsy specimens are taken from the prostate and sublumbar lymph nodes. Neoplastic tissue must be excised, and this can require extensive urethral resection. Margins, especially of the urehra, are sampled in order to stage the cancer spread. Retraction sutures in the urethra caudal to the prostate can reduce traction problems. The urethra is transected cranial (Figure 32-2C) and caudal to the prostate (Figure 32-2D). The prostate is removed, and the urethral catheter is redirected into the bladder. The urethra is anastomosed with interrupted sutures using an absorbable monofilament synthetic suture material, usually of 4-0 or 5-0 size (Figure 32-2E). Some urethras are thick enough that a second layer of sutures can be placed in muscle tissue. A cystostomy catheter is placed in addition to the urethral catheter to ensure that urine is diverted and that little tension is placed on the anastomosis (Figure 32-2F). Both catheters are left in place for 1 week, and urine is collected by a closed system. The balloon of the cystostomy catheter is deflated, and the catheter is withdrawn 1 week after the surgical procedure. The urethral catheter is left in place for another day and then is withdrawn.
 

Partial Prostatectomy

Partial prostatectomy is my preferred procedure for treatment of patients with prostatic cysts and abscesses, but it is contraindicated for cancer. The use of the ultrasonic surgical aspirator permits removal of up to 85% of the prostatic glandular tissue in addition to all cysts and abscesses. Because the remaining prostatic tissue is dorsal and close to the urethra, most of the urethral innervation and muscles appear to be left intact. Incontinence is much less frequent and severe after partial prostatectomy of dogs with severe cavitary disease than before the surgical procedure or after ex-cisional prostatectomy. As with excisional prostatectomy, castration should be performed.

The prostate is approached in the same fashion as previously described, except dorsal and lateral dissections are avoided or at least limited. After obtaining biopsy specimens and after placing the aortic tourniquet and retraction suture about the urethra caudal to the prostate, the surgeon incises poles of the prostate ventrally with electrocautery (Figure 32-3A). The Cavi-tron Ultrasonic Surgical Aspirator (CUSA System 200 Macro-Dissector, Valleylab, Inc., Pfizer Hospital Products Group, Boulder, CO) is used to fragment, irrigate, emulsify, and aspirate approximately 85% of the glandular tissue (Figure 32-3B and C). A catheter is placed within the urethra to identify and avoid damaging it. Urethral fistulas are identified by inflating the urethra with fluid (Figure 32-3D). After glandular dissection and excision of the ventral hemisphere on the ventral midline of the capsule, omentum is placed over the urethra and the dorsal prostatic capsule is suture around the omentum and urethra on the ventral side to form a cuff around the prosatic urethra.
 

Postoperative Care and Complications

Early potential complications can include shock potentially leading to death, infection (sepsis), pain, and renal shutdown. Fluid support should be continued at greater than maintenance rates based on monitoring results of, initially, arterial blood pressure and, later, volume of diuresis. If shock develops, treatment must be aggressive. Urinary output is recorded, and the bladder is evaluated frequently to ensure that it remains decompressed. Urinary catheters are usually removed during the first 2 days after partial prostatectomy. For excisional prostatectomy, catheters are left for 1 week and require protection with side braces or Elizabethan collars. Antibiotics are continued. Pain medications are normally given at least during the initial 8 hours after surgery. Intensive care monitoring is critical for several hours postoperatively. In addition to monitoring of urine output, temperature, pulse, and respiration, and attitude, complete blood counts with platelet counts, blood urea nitrogen, albumin, glucose, and urinalysis should be performed. Liver enzymes are also useful to detect signs of sepsis and septic shock. In dogs with signs of sepsis, decreasing albumin concentrations indicate a need for plasma. Nutritional status should be documented by measuring food intake and body weight daily. No deaths have been reported in dogs treated by partial prostatectomy.

Long-term complications of surgical treament in dogs with severe prostatic disease include persistent infections and disease, as well as incontinence. Dogs usually urinate normally after partial prostatectomy, and fewer than 20% of dogs have even minor urinary control problems. After excisional prostatectomies, most dogs develop mild incontinence, and a few (approximately 10%) have continual dribbling of urine. Prostatectomy of normal dogs produces no decrease in urinary control function and only minor urodynamic changes, but the combination of prostatic disease and removal of the prostate increases incontinence. Some incontinent dogs with low urethral pressures have been successfully treated with phenylpropanolamine (1.5 mg/kg orally three times daily), and those with detrusor instability have been treated with oxybutynin (2.5 mg orally three times daily). Recurrent prostatic infections and disease should not occur when the prostate has been excised. Dogs with partial prostatectomy have not had recurrence during the first year after discharge from the hospital. Complications have been seen during hospitalization when a urethral to cyst fistula either persisted or recanalized. This fistula can been repaired during an additional surgery. Since a small amount of prostatic tissue is present and can be infected, at least two dogs have developed recurrent disease more than 1 year after surgery. The potential for urinary tract infection is high in any dog following surgery for major prostatic disease. These dogs must have regular urinalysis and cultures combined with aggressive antibiotic therapy. Intense surveillance and treatment should reduce problems with recurrent infections.

Acknowledgment

The illustrations by Dan Biesel and Kip Carter are appreciated.

Suggested Readings

Basinger RR, Rawlings CA. Surgical management of prostatic diseases. Compend Contin Educ Small Anim Pract 1987,9:993-1000.

Basinger RR, Rawlings CA, Barsanti JA, et al. Urodynamic alterations after prostatectomy in dogs without clinical disease. Vet Surg 1987;6:405-410.

Basinger RR, Rawlings CA, Barsanti JA, et al. Urodynamic alterations associated with clinical prostatic diseases and prostatic surgery in 23 dogs. J Am Anim Hosp Assoc 1989;25:385-392.

Cowan LA, Barsanti JA, Crowell W, et al. Effects of castration on chronic bacterial prostatitis in dogs. J Am Vet Med Assoc 1991,199:346-350.

Hardie EM, Barsanti JA, Rawlings CA. Complications of prostatic surgery. J Am Anim Hosp Assoc 1982;20:50-56.

Mullen HS, Mathieson DT, Scavelli TD. Results of surgery and postoperative complications in 92 dogs treated for prostatic abscessation by a multiple Penrose drain technique. J Am Anim Hosp Assoc 1990;26:369-379.

Rawlings CA, Crowell WA, Barsanti JA, et al. Intracapsular subtotal prostatectomy in normal dogs: use of an ultrasonic surgical aspirator. Vet Surg 1994;23:182-189.

Stone EA, Barsanti JA, eds. Urologic surgery of the dog and cat. Philadelphia: Lea & Febiger, 1992.

White RAS, Williams JM. Intracapsular prostatic omentalization: a new technique for managment of prostatic abscesses in dogs. Vet Surg 1995;24:390-395.
 

Causes of Prostatic Abscesses and Cysts

Abscessation of the prostate gland in dogs is considered to result from an ascending bacterial infection that overcomes the normal urethral defense mechanisms and thereafter colonizes the prostatic parenchyma. A suppurative infection resulting in parenchymal microabscesses is thought to develop subsequently, but the precise mechanism by which these microabscesses coalesce into larger, loculated abscesses rather than remaining as diffuse prostatitis is unclear. The most commonly recovered organism is Escherichia coli, with Staphylococcus spp. and Proteus spp. occasionally encountered.

Discrete cysts involving the prostate gland are a well-defined but uncommon manifestation of prostatic disease. Two distinct categories of cyst have been previously described namely, paraprostatic and prostatic retention cysts. It now seems clear that both types of cysts in fact share a common etiology and are thought to develop as the result of obstruction of ducts within the parenchyma of the gland promoting the accumulatic of prostatic secretions. Concurrent prostatic disease is always present, and this may include benign prostatic hyperplasia, squamous metaplasia, abscessation, or neoplasia. Discrete cysts are capable of attaining considerable size and should be distinguished from the diffuse cystic changes that often occur in combination with benign prostatic hyperplasia.

Clinical Signs and Diagnosis

Dogs with prostatic abscesses are pyrexic and have signs of caudal abdominal pain on rectal and transabdominal palpation of the prostate gland. The prostate gland is invariably enlarged and may have a doughy feel when palpated. Many dogs have neutrophilia (white blood count higher than 17 x 10⁹/L), but this is not a consistent feature of the disease. Alkaline phosphatase concentrations may be elevated in some patients. Radiography enables one to confirm the prostatic enlargement, but ultrasound imaging is necessary to demonstrate the characteristic loculation within the parenchyma that contains the slightly echodense purulent fluid. Fine-needle aspiration may be used to recover purulent material, but it should be performed with care to avoid the risk of peritonitis after this procedure.

Prostatic retention cysts are encountered mostly in large breed dogs, especially boxers. Signs of urinary dysfunction, including stranguria, dysuria, hematuria, and incontinence, are invariably seen. Palpation identifies a caudal abdominal mass. A presumptive diagnosis of prostatic cyst can be made by evaluation of survey abdominal radiographs and ultrasound examination of the prostate in all dogs. Mineralization of the cyst wall is evident in some dogs. Biopsy may be indicated because some retention cysts accompany prostatic neoplasia, but fine-needle aspiration should again be performed with care.

Conventional Drainage Strategies

Chronic parenchymal lesions of the prostate gland, most notably abscesses and discrete cysts, are difficult clinical entities to resolve consistently by means of medical or surgical therapy. Various surgical techniques have been described for the management of prostatic abscesses and cysts.

Abscesses

The use of antibiotic therapy, even in conjunction with castration, is notoriously ineffective in resolving prostatic abscessation because of its failure to achieve adequate therapeutic concentrations throughout the prostate. Previously described techniques for drainage or removal of abscesses include marsupialization of the abscess, local resection, subtotal prostatectomy, and excisional prostatectomy. For many years, the most widely practiced technique was ventral drainage by means of dependent Penrose drains. All the foregoing techniques necessitate prolonged postoperative management, and long-term complications associated with these procedures include recurrent abscessation, chronic drainage after marsupialization, urinary incontinence, urinary tract infection, and the development of urethrocutaneous fistula.

Prostatic Retention Cysts

Marsupialization of prostatic cysts is a comparatively simple technique, but persistent discharge from the stoma, chronic urinary tract infection, and abscessation are recognized complications. Drainage and surgical resection of the cyst comprise a successful technique and should be regarded as the technique of choice for the management of paraprostatic cysts, for which the dissection is often uncomplicated. Many prostatic retention cysts, however, have extensive adhesions to the ureters, bladder neck, and prostate, and complete resection may increase the risk of postoperative incontinence or urinary retention resulting from neural or vascular compromise. Partial cyst resection may therefore be a preferable strategy to minimize the risk of incontinence, although this procedure may permit continued fluid secretion, redevelopment of the cyst, or formation of adhesions between the cyst remnant and other abdominal organs.

Omentum for Prostatic Drainage

The value of the omentum as an alternate source of vascularization and lymphatic supply in veterinary surgery is well established. Recognized applications include reconstruction of body wall deficits, filling of dead space, support for grafted tissue, reinforcement of gastrointestinal or urogenital repairs, and resolution of chronic wounds. The omentum is able to resolve bacterial contamination from perforated viscera and even can function in the presence of infection. The omentum can be used as a “physiologic drain” to resolve lesions of the prostatic parenchyma such as abscesses or to provide continued drainage of ongoing secretions from residual cystic tissue without merely walling them off from the abdominal cavity. Additionally, the omentum creates adhesions at the operative site, thereby minimizing the risk of visceral adhesion.

Intracapsular Prostatic Omentalization for Prostatic Abscesses

A caudal celiotomy extending from the umbilicus to the pubic brim is performed to permit adequate elevation of the prostate gland, which is then packed off from the remainder of the abdomen with moist laparotomy sponges. Stab incisions are made bilaterally in the lateral aspects of the prostate gland, and pus is removed by suction to minimize abdominal contamination. All abscess loculations within the parenchyma (Figure 32-4) are explored and are broken down by digital exploration. The prostatic urethra is carefully preserved and can be identified by palpation of a previously placed urethral catheter. A Penrose drain may be temporarily placed around the prostatic urethra within the parenchyma to help elevate the gland and to facilitate irrigation of the abscess cavities with warm saline. The stab incisions are then enlarged by resection of the lateral capsular tissue. Artery or tissue forceps are introduced into one capsulectomy wound and are used to draw a leaf of omentum into the contralateral wound and through the dorsal abscess cavity (Figure 32-5). The omentum is passed back through the ventral cavity, resulting in complete periurethral packing, to exit the prostate, and is then anchored to itself with absorbable mattress sutures outside the prostate gland (Figure 32-6). The celiotomy wounds are closed routinely, and castration is performed. Dogs should receive broad-spectrum antibiotic therapy periopera-tively, but this therapy does not need to be extended postoperatively unless complications occur, such as major contamination of the abdominal cavity before or during the surgical procedure.
 

Partial Resection and Omentalization for Prostatic Retention Cysts

A caudal celiotomy extending from the umbilicus to the pubic brim is performed. The cyst is identified (Figure 32-7), and a single stab incision is made through the cyst wall. Complete drainage using suction to avoid con tamination of the abdominal cavity is performed (Figure 32-8), and the majority of the cyst wall is resected (Figure 32-9). Extensive dissection of the cyst in the region of the bladder neck and prostate should be avoided, to minimize the risk of damaging nerves that control continence. Omentum is packed into the cyst remnant and is secured in place (Figure 32-10) with mattress sutures of 2-0 absorbable suture material. The prostate gland should be carefully examined and palpated during the surgical procedure, and if neoplastic infiltration is suspected, an incisional biopsy should be performed. The celiotomy wounds are closed routinely, and castration is performed. Dogs should receive perioperative broad-spectrum antibiotics, which may need to be extended postoperatively if purulent debris is apparent in the cyst during the surgical procedure.
 

Postoperative Care and Complications

A significant advantage of omentalization drainage techniques for prostatic disease is that patients can normally be discharged from the hospital within 24 hours of the surgical procedure. As already indicated, prolonged antibiotic therapy is only necessary if complications are encountered.

Abscesses may recur if insufficient omentum is packed into the abscess cavity. The surgeon should ensure that adequate lateral capsulectomy resections—normally sufficient to accommodate the easy entry of the forefinger into the abscess cavity—are performed to avoid this complication.

Urinary incontinence is a frequent presenting sign in patients with prostatic retention cysts, and this problem may persist even after successful omentalized drainage of the cyst. Therapy with phenylpropanolamine (1 mg/kg every 24 hours orally) to increase urethral sphincter tone may be appropriate in some of these patients. Urinary retention is less common, and the patient’s urinary function should be monitored carefully during the first 24 hours after the surgical procedure.

Prognosis

Omentalized drainage has proved successful for the management of both prostatic abscesses and retention cysts. Compared with other drainage techniques, the level of surgical expertise required for successful omentalization is modest, hospitalization stays are brief, and postoperative complication rates are low.

Suggested Readings

Basinger RR, Rawlings CA, Barsanti JA, et al. Urodynamic alterations associated with clinical prostatic diseases and prostatic surgery in 23 dogs. J Am Anim Hosp Assoc 1989;25:385-392.

Gourley LG, Osborne CA. Marsupialization: a treatment for prostatic abscess in the dog. J Am Anim Hosp Assoc 1966;2:100-105.

Hardie EM, Barsanti JA, Rawlings CA. Complications of prostatic surgery. J Am Anim Hosp Assoc 1984;20:50-56.

Hardie EM, Stone EA, Spaudling KA, et al. Subtotal canine prostatectomy with neodymium yttrium-aluminium-garnet laser. Vet Surg 1990,19:348-355.

Hosgood G. The omentum—the forgotten organ: physiology and potential surgical applications in dogs and cats. Compend Contin Educ Pract Vet 1990,12:45-51.

Mullen HS, Matthiesen DT, Scavelli TD. Results of surgery and postoperative complications in 92 dogs treated for prostatic abscessation by a multiple Penrose drain technique. J Am Anim Hosp Assoc 1990;26:369-379.

Rawlings CA, Crowell WA, Barsanti JA, et al. Intracapsular subtotal prostatectomy in normal dogs: use of an ultrasonic surgical aspirator. Vet Surg 1994;23:182-189.

White RAS, Williams JM. Intra-capsular prostatic omentalization: a new technique for management of prostatic abscessation. Vet Surg 1995;24:390-395.

White RAS, Herrtage ME, Dennis R. The diagnosis and management of paraprostatic and prostatic retention cysts in the dog. J Small Anim Pract 1987;28:551-574.