Diseases of the Esophagus and Nutritional Approach

7. Diseases of the Esophagus and Nutritional Approach

Conformation Abnormalities of the Esophagus

Vascular Abnormalities

The persistence of some vascular arches in the course of embryogenesis may cause extrinsic compression of the esophagus, leading to the formation of a crop above the stenosis. The most commonly described abnormality is the persistence of the fourth arch of the right aorta (Twedt, 1994). The esophagus is clasped in an adhesion formed by the aorta, the non-vascularized residual arterial ligament and the pulmonary artery. The diagnosis is based on radiography (localized proximal esophageal dilatation) and endoscopy, and the treatment is surgical. Other abnormalities have been reported in carnivores (double aortic arch, persistence of subclavian arteries), but these conformation faults remain exceptionally rare in cats.

Esophageal Fistulas

Esophageal fistulas are rare in carnivores. They extend from the esophageal wall to the mediastinum or even the chest cavity. They are congenital, although they can result from trauma. Signs are mostly of a respiratory nature (dyspnea, coughing, fever). The diagnosis is based on radiography with contrast medium or esophagoscopy.

Megaesophagus: Medical Aspects

Megaesophagus is a generalized dilation of the esophagus with partial or total loss of peristalsis and motility (Figure 17). The congenital form is distinguished from the acquired form, the origin of which is sometimes identified or remains undetermined (idiopathic megaesophagus) (Strombeck, 1978).

Figure 17. Thoracic radiograph of a cat consistent with megaesophagus. The esophageal wall, normally not seen, is visible here (two radiodense lines). (©V. Freiche).  

Epidemiology and Pathophysiology

Congenital Megaesophagus
The congenital form is described in Asiatic breeds, specifically the Siamese (Tams, 1996). While it has not been possible to show vagal innervation deficits, modification of the conduction of the afferent reflex arches that generate peristalsis can be suspected. Motility problems are implicated in the pathogenesis of congenital megaesophagus (contractions of ineffective amplitude, alteration of parietal elasticity).

Acquired Megaesophagus

No epidemiological studies have established any breed or sex predisposition for the acquired forms, and no hereditary transmission mechanism is suspected. All disorders entailing parietal lesions of the esophagus or an innervation fault are likely to cause the appearance of megaesophagus.

In the absence of clinical factors suggesting another etiology, acquired megaesophagus in cats should give rise to the hypothesis of dysautonomia. The involved pathogenic mechanisms have not been clearly described. This general disorder of the neurovegative nervous system means that colonic atony is often associated and the clinical signs are much more complex. The appearance of esophageal motility problems – even isolated – may also suggest severe myasthenia (Moses et al., 2000).

Clinical Signs

In the congenital forms the clinical expression often manifests itself during weaning: ever more frequent regurgitations, stunted growth compared with other kittens in the same litter. In some cases the regurgitations occur well after mealtimes, and owners may interpret them as vomiting, which may cause the clinician to orient towards an incorrect diagnosis.

Other clinical signs described are halitosis, abnormal sounds from the esophagus, coughing secondary to aspiration pneumonia (Jenkins, 2000). However, not all cats with megaesophagus present with respiratory signs. Conversely, respiratory disease is sometimes very important.

Palpation of the esophagus may reveal a perceptible dilatation of the ventral part of the neck. A muco-purulent discharge and audible rales are noted in the event of infectious pulmonary complications. The impairment of the general condition is inconsistent.

Diagnosis

Radiographs of the thorax are used for the diagnosis. In case of doubt radiographs taken after the administration of contrast medium can confirm the esophageal dilatation. Digestive endoscopy is not among the complementary tests that help confirm the diagnosis.

Plain Radiography

The esophagus cannot usually be seen on a plain radiograph. Increased esophageal radio transparency is therefore abnormal. The size of the dilatation is variable. It may affect the whole organ or only the thoracic part of it. A radiodense line emphasizes the dorsal wall. These modifications are identifiable on the lateral and ventro-dorsal views. It is important that good quality radiographs are obtained to enable evaluation of the pulmonary tissue for characteristic densities and alveolar infiltrates, which are characteristic of aspiration pneumonia.

Radiography with Contrast Medium

The administration of a contrast medium (Figure 18) will be necessary if the animal experiences deglutition problems or regurgitations if the plain radiographs are normal or insufficient to establish a definite diagnosis. The contrast medium may be a barium sulfate paste, but this is contraindicated in the event of dysphagia due to the risk of aspiration. Barium is very irritating for the bronchi. In this situation, an iodized product is recommended for contrast enhancement.

Figure 18. Extensive esophageal dilatation in a cat who presented for both dysphagia and severe respiratory difficulties. Thoracic contrast radiography with barium. (©V. Freiche).  

Endoscopy

In the event of megaesophagus, endoscopy can evaluate the integrity of the surface of the mucosa, but it is not the most reliable test for assessing the size of the esophageal lumen. However, in case of doubt in the differential diagnosis, it does help refine the diagnosis and exclude the presence of associated esophagitis.

Differential Diagnosis

Owners are often imprecise in describing clinical signs. It is not uncommon for tardy regurgitations to be confused with very early vomiting. The differential diagnosis should include all other disorders that may cause dysphagia or ptyalism:

• Pharyngeal disorders: foreign body, laryngeal paralysis (achalasia: very rare in cats)
• Other esophageal lesions: foreign body, vascular abnormalities (crop), neoplasia (rare) (Figure 19).

Figure 19. Esophageal tumor in a 14-year-old European cat. Histological examination indicated an undifferentiated carcinoma. (©Dr Dominique Blanchot).

Treatment

The treatment of congenital megaesophagus or idiopathic acquired megaesophagus is based on hygienic and palliative measures. It makes great demands on the owner: feeding the animal in a raised position improves the assimilation of the food due to gravity. The consistency of the diet is an important but inconsistent factor: some cats regurgitate less with a liquid food, others have more success with solids.

In the event of bronchopulmonary complications, complementary symptomatic medical treatment can be commenced.

• Prokinetic substances (e.g., cisapride) may enable better esophageal clearance in cats as the distal section of the esophagus is comprised of smooth muscles. Unfortunately, cisapride is no longer readily available in every country.
• Antibiotic therapy is indispensable in the event of secondary bronchopulmonary lesions.
• Mucosal protective agents are indicated if erosive parietal lesions are identified.

However, the prognosis is sometimes so poor (especially in kittens) that euthanasia is ultimately chosen.

Esophagitis

Inflammation of the esophageal mucosa (Figure 20) may be secondary to local trauma (ingestion of toxins, prolonged presence of a foreign body) or to repetitive gastroesophageal reflux (lower esophageal sphincter incompetence, degenerative disorders) (Lobetti & Leisewitz, 1996; Han et al., 2003). General anesthetics (barbiturates) reduce the pressure of the caudal esophageal sphincter, favoring peri-operative reflux (Freiche, 2006a). In rare cases, stenosing parietal lesions appear. The composition and acid pH of the gastric fluid makes it highly irritating for the esophageal mucosa.

Figure 20. Endoscopy of the distal esophagus of a cat. Note the presence of erythematous punctures consistent with an acute inflammatory state. (©V. Freiche).

Clinical Manifestations and Diagnosis

These are not very specific and include pain during deglutition, hypersalivation, and dysphagia. Sometimes, the clinical signs are simply prostration associated with dysorexia.

All inflammatory disorders of the esophagus are likely to be secondary to functional problems due to alteration of motility. These peristaltic problems are very difficult to document in domesticated carnivores. The examinations of choice are fluoroscopy and endoscopy.

Medical Treatment

Nil per os is required to manage highly erosive or diffuse esophageal lesions (see the section on Esophageal Foreign Bodies).

Antacids

The administration of antisecretors and antacids help increase the gastric pH and reduce the risks of parietal erosion in the event of reflux. The most commonly used substances are anti-histamine – 2 agents (cimetidine, ranitidine, famotadine etc) and proton pump inhibitors (omeprazole and derived substances). They must be administered for at least fifteen days. Cimetidine favors augmentation of the caudal esophagus sphincter tone, which is often deficient in esophagitis.

Local topical agents including aluminum-based cytoprotectives, sucralfate, or an association of alginic acid and sodium bicarbonate, are beneficial adjuvant treatments:. Administered at the end of the meal, they constitute a protective film on the surface of the mucosa and protect the mucosa from reflux.

Antibiotic Therapy

Antibiotic therapy is indispensable in combating local bacterial translocation. It helps prevent more serious lesions. When there are too many lesions on the mucosa or perforation is suspected, the administration of ampicillin is recommended. The association of cephalosporin and metronidazole may be proposed.

Corticosteroids

Their use in the prevention of stenosis is highly controversial. Experimentally, their preventive activity has not been proven. Conversely, they are implicated in the mechanism of perforation during preexisting parietal necrosis. Administered over short periods, they limit pain and present local anti-inflammatory properties.

Inserting a Gastrostomy Tube

With severe esophagitis, local mechanical trauma in the mucosa can be reduced if no solid or liquid passes through the esophagus for several days. Another advantage of fasting is the reduction in the local fibroblastic reaction, which favors the appearance of a healing stenosis. A gastrostomy tube must be placed at the end of esophagoscopy. An anastomosis is created within a few days between the stomach wall and the abdominal wall. The administration of an energy dense diet and medical treatment is achieved several times a day using syringes connected to a three-way valve attached to the tube. This care can even be provided by the owner following simple instruction. Local tolerance is good (Ireland et al., 2003). Energy density of the enteral diets should be high and fat as energy source is best suited for that purpose. In many cases, blended canned diets can be used. Bolus-feeding techniques can maintain a normal nutritional status in cats.

Esophageal Stenosis

The appearance of isolated stenosing lesions of the esophageal wall most commonly follows the ingestion of caustic products or the onset of postoperative gastroesophageal reflux (Sellon & Willard, 2003; Freiche, 2006a). In cats, the oral administration of tetracyclinehas been implicated in the genesis of severe stenosing esophageal lesions (McGrotty & Knottenbelt, 2002; German et al., 2005). Less commonly, these lesions appear postoperatively (Figure 21) or after the extraction of a foreign body.

Figure 21. Post-operative peptic esophageal stenosis in a 4-year-old female cat. (©V. Freiche).

Esophageal stenosis is predominantly benign in cats. The mucosa loses its elasticity and the affected section becomes fibrotic (simultaneous disorder of the lamina propria and the muscle wall). There does not appear to be any preferred location in the esophagus; lesions can be proximal or distal, or even in multiple locations in the same animal.

Clinical Manifestations

The two clinical signs of stenosis are regurgitation and esophageal dysphagia, the latter of which is a deglutition problem. It may be the consequence of pain or even alteration of the motility inherent to the lesion.

The clinical signs may manifest acutely (dyspnea, often pronounced dysphagia after ingestion of solids but also after ingestion of liquids if the stenosis is pronounced). They are correlated to the severity of the stenosis. The animal may lose weight rapidly. The lesions are incompatible with medium-term survival if the residual diameter of the esophageal lumen is less than 8 mm.

Diagnosis

Thoracic radiography with or without contrast medium and esophageal endoscopy confirm the diagnosis. The differential diagnosis must exclude other causes of chronic vomiting or regurgitation:

• Megaesophagus (rare in cats)
• Esophageal crop due to vascular abnormality (rare in cats)
• Diverticulum (rare in cats)
• Hiatal hernia in the strict sense / gastroesophageal invagination (rare in cats)
• Esophageal foreign body (less common in cats than in dogs in this location)

Thoracic Radiography

When stenosis is the consequence of parietal fibrosis the plain radiographs do not reveal any abnormalities. Air dilatation may be suspected in front of the lesion, as the esophagus is normally radio-transparent. Food residues may persist and create local contrast that permits diagnostic suspicion. Abnormal images may be seen if there is extrinsic or intrinsic compression by an endoluminal mass.

Radiographs after the ingestion of a contrast medium are often necessary to confirm the diagnosis (introduction of barium under anesthesia using a tube or fluoroscopy): this also helps provide an initial assessment of the scope of the stenosis.

Indications and Limitation of Esophagoscopy

Endoscopy is the diagnostic test of choice in the exploration of this type of lesion (Figure 22a and Figure 22). The limit of the examination is the diameter of the lesion, which sometimes limits the passage of the endoscope towards the distal part of the esophagus. Esophagoscopy is complementary to radiography: it can be used to assess the residual diameter of the esophagus. The images obtained in the event of (post-reflux) peptic esophagitis are very characteristic.

Figure 22a. Esophageal stenosis in a 8-year-old DSH cat. This serious lesion has a peptic origin and has appeared after a general anesthesia realized for a convenience surgery. (©V. Freiche).

Figure 22b. Esophageal stenosis in a cat, secondary to a thoracic tumor. In this particular case, due to the origin of the stenosis, endoscopic dilatation is not a therapeutic option. (©V. Freiche).

The endoscope examination provides an assessment of the residual diameter of the esophagus (Figure 23). It is conducted at the end of the diagnostic radiograph with contrast medium to evaluate the scope of the stenosis. The benefits of endoscopic treatment can also be assessed. If the stenosis is unique and short in length, endoscopic dilatation is indicated. The results are less certain if the stenosis extends for several centimeters or if there are multiple areas of stenosis.

Figure 23. Insertion of a thoracic labeling tube to measure the extent of esophageal stenosis. The cat was presented for dysphagia. The esophageal compression was extrinsic. (©V. Freiche).  

Treatment of the Stenosis: Practicalities

The treatment consists of several dilatation appointments using a balloon tube, which can be inflated under manometric control (Haraï et al., 1995; Adama-Moraitou et al., 2002). The balloon catheter is introduced in the operator channel of the endoscopy. There is a tube sized to suit every case. The aim is to achieve repetitive parietal dilaceration in the cicatricial zones (Freiche, 1999; Leib et al., 2001). However, in the case of annular stenosis with little fibrosis, the mucosa retains sufficient elasticity locally to enable perendoscopic dilatation without local dilaceration being visible at the end of the dilatation maneuvers: in this particular case, a surgical approach must be considered. The aim is to achieve a residual diameter of at least 10 mm at the end of treatment.

Results and Complications

The results are generally good when the indication has been properly determined. Endoscopic dilatations do not involve much pain, so they are well tolerated by the animal and lead to general recovery in a few weeks. Extended stenosis may however have a very poor prognosis. The same is true of multiple forms of stenosis or when the stenosis is the consequence of a neoplastic lesion.

Three to five successive appointments every couple of days are suggested for this type of treatment. A reduction in the diameter of the esophagus is systematic between two appointments due to the inevitable partial parietal cicatrisation. The in situ injection of local corticosteroids using an endoscopic catheter helps to limit this complication. This technique should be attempted initially. If such lesions are initially treated surgically, a new stenosis is likely to appear at the surgical site.

Immediate Complications

The major risk is parietal rupture during the examination, which is rare. A surgical team must be ready to intervene in the event of complications.

Medium-term Complications

Esophageal motility is always altered when a lesion is identified in this organ, regardless of the origin. The treatment of stenosis does not guarantee a return to the normal motility activity of the esophagus. For this reason, some cats are euthanized due to the persistence of dysphagia or the appearance of pulmonary complications related to aspiration.

Esophageal Foreign Bodies

The rather unselective dietary behavior of carnivores means that the ingestion of foreign bodies is a relatively common reason for consultation. Cats are more ‘delicate’ than dogs, so the incidence of foreign bodies in the esophagus and stomach is much less important in the former.

In cats, linear foreign bodies in the esophagus are often due to a twine or thread becoming trapped under the tongue (Figure 24) and lodging in the digestive tract. In this situation, it cannot be extracted by endoscopy. A wide array of objects is ingested, including needles and hooks.

Figure 24. Twine visible in the esophagus of a one-year-old male Exotic Shorthair. The twine is lodged in the digestive tract. (©V. Freiche).  

According to studies, foreign bodies tend to lodge where the esophagus contracts, especially at the diaphragmatic hiatus or the entrance to the thorax, although the base of the heart is also possible.

Clinical Diagnosis

The presence of a foreign body in the esophagus can produce alarming clinical signs and demands urgent intervention. Information from the owner is vital as it may provide pointers as to the type of foreign body ingested and especially when it was ingested. These factors impact the choice of the extraction method. On average, the duration between ingestion of the foreign body and presentation to the veterinarian varies from a few hours to a few days.

The severity of the clinical signs depends on the degree of esophageal obstruction and damage to the esophageal wall. If the lumen is only partially obstructed and the esophagus is not perforated, the animal may present in a subnormal clinical state allowing the absorption of liquids without difficulty. This explains why some foreign bodies are not discovered for some time. The differential diagnosis involves all the other causes of esophageal obstruction (neoplasia, congenital anomalies, extrinsic compressions).

When a foreign body is lodged in the esophagus, the animal often presents characteristic clinical signs:

- Dysphagia
- Anorexia
- Fever (more inconsistent)
- Ptyalism
- Lethargy or agitation
- Halitosis
- Pain
- Regurgitation
- Breathing difficulties
- Weight loss

Cervical palpation is abnormal when the foreign body is lodged in this area (needle).

Complementary Tests

Plain Radiography

This simple and fast procedure will help confirm the diagnosis in more than 85% of cases according to the statistical data described in the literature (Durand-Viel & Hesse, 2005). The radiological signs may be:

• Direct, when the foreign body is radiodense (bone, metallic)
• Indirect, in the event of partial esophageal dilatation or the presence of an abnormal quantity of air or liquid

Radiography with Contrast Medium

If the images are unable to help confirm the clinical suspicion, radiographs with contrast medium are required. If there is a strong suspicion of a perforated esophagus, an iodized labeling product is preferred over the administration of barium sulfate. Persistence of the contrast agent in front of the lesion or the presence of an image by subtraction, indentified in several consecutive images, is suggestive.

Esophagoscopy

This step is therapeutic. It confirms the nature of the foreign body – after other causes of obstruction or esophageal compression have been excluded – and it helps in the choice of therapy: attempted removal of the foreign body or surgery.

Practical Procedure
The endoscope is used to assess the shape of the foreign body, how tightly it is lodged between the mucosa and how much it can be moved. A foreign body that is initially difficult to move (like a hook) is often more difficult to extract (Figure 25).

Figure 25. Close-up of the end of a hook lodged in the esophageal mucosa of a cat. An ulcerative lesion is probably present under the lodgement area. (©V. Freiche).  

There are limits to endoscopic extraction:

• Suspicion of esophageal perforation,
• Highly ulcerated mucosa (risk of esophageal rupture),
• Local superinfection in the event of delayed intervention.

Local evaluation of the condition of the mucosa is an important criterion in the decision-making process. If the foreign body has been lodged for more than 72 hours, the risk of perforation is much higher. Generally speaking, it is accepted that all extraction techniques using an endoscope must be attempted before the surgical option is used.

Results and Complications
According to the literature, the success rate of this type of intervention varies between 60% and more than 90% (Durand-Viel & Hesse, 2005). The latter figure is correlated to the speed of intervention after ingestion of the foreign body, as the condition of the esophageal mucosa deteriorates rapidly when in permanent contact with a foreign body, especially a bone.

If there are clear indications, this procedure has a number of undeniable advantages:

• Limits tissue trauma
• Speed of functional recovery
• Reduces post-surgery care
• Timesaving

The following complications are described:

• Massive local hemorrhage (close to the large vessels in the periesophageal area) (Cohn et al., 2003)
• Tears, perforations of the esophageal mucosa, deep ulcerations produced during the movement of the foreign body

While the post-intervention lesions in the esophagus or stomach may be large, a tailored medical treatment produces active and rapid healing of the esophageal mucosa (see Esophagitis).

Repeat esophagoscopy is recommended in the event of ulcerative lesions. It must be conducted within four or five hours of extraction. If these lesions are too large, provision of food or water is contraindicated. An enteral feeding tube (PEG) is inserted endoscopically at the end of the examination (Mark, 2005; Wortinger, 2006).

Esophageal Neoplasia

Different Histological Types Encountered

Esophageal tumors are very uncommon in cats, contrary to humans. Esophageal tumors account for less than 0.5% of all cancer cases in domesticated carnivores (Ettinger & Feldman, 2000). They usually affect aging animals. The most common histology types are undifferentiated carcinomas, osteosarcomas and fibrosarcomas (Tams, 1996; Gualtieri et al., 1999; Shinozuka et al., 2001). In cats, the carcinoma is the most commonly described tumor, although it is much less common than it is in dogs. Benign tumors are rare and often asymptomatic (leiomyomas, papillomas).

In the event of helminthiasis caused by Spirocerca Lupi described in Africa, in Réunion and some parts of the United States and Guyana, the migration of larva from the stomach to the thoracic aorta ends in the implantation of an adult parasite in the esophageal wall. This causes the appearance of local nodules, which are likely to undergo neoplastic transformation. The infestation of carnivores mostly occurs after the ingestion of small reptiles or rodents (early treatment of these nodular lesions is with ivermectin). These tumors of parasitic origin generally have a poor prognosis when the diagnosis is established and their metastatic potential is high (Guilford & Strombeck, 1996c; Freiche, 2005a). While this larval migration is well described in dogs, its appearance is more anecdotal in cats.

Clinical Signs

The clinical signs are non-specific to the primary lesion, dominated by dysphagia, the intensity of which is related to the degree of esophageal obstruction. The regurgitations are associated with other clinical signs: ptyalism, dysorexia, odynophagia and alteration of general condition. Hematemesis is reported when there is local ulceration. Signs of pneumonia may be secondary to aspiration.

The esophageal wall may also be the site of compressive phenomena of extrinsic origin with thoracic lymphoma, lymphadenopathy, pulmonary neoplasia or thymoma, but they are not primary esophageal tumors.

Diagnosis

The diagnosis of esophageal tumors is sometimes delayed as the clinical signs manifest themselves at an advanced stage of development. Suspicion is supported by radiographic examination (with or without contrast medium) or ultrasound if the mass is distal. However, the examination of choice to establish a precise diagnosis is esophagoscopy (Figure 26), which enables biopsy, a reliable evaluation of the extent of the lesion, and the surgical options. If the mass is under the mucosa, a tomodensitometric examination is complementary.

Figure 26. Malignant esophageal tumor in a 14-year-old European cat. (©D. Blanchot).  

Disease staging is based on thoracic radiography. Malignant lesions are aggressive and can metastasize rapidly. In cats, the preferred sites of metastasis of esophageal carcinomas are the lymph nodes in the thorax, the lungs, the kidneys and the spleen.

Treatment and Prognosis

The surgical approach to esophageal tumors is complex because of the risk of local dehiscence of the sutures and the impossibility of wide resection. The prognosis of malignant lesions is often very low in the short term. The chemotherapeutic protocols proposed on the basis of the histological origin of the lesion therefore have only a palliative benefit.

Nutritional Approach to Esophageal Diseases

If enteral feeding is not contraindicated and the patient accepts it, food and water bowls should be raised. Cats can be fed "over-the shoulder". Patients can also be held vertical for a short while after feeding. This procedure facilitates the passage of food to stomach. If the patient needs assisted feeding for a longer period, energy and nutrient intakes and fluid volume have to be carefully balanced. The diet should deliver the complete nutrient spectrum in a reasonable volume.

High fat diets are preferred because of their higher energy density. The optimum type of food varies between cases. For some, high-quality liquid diets are best, for others, wet food or moisturized dry food is suitable. Diet viscosity should also be considered.