Feline oesophagitis and oesophageal strictures

© August, JR. (2006) Consultations in feline internal medicine. Elsevier Inc, PA.

Oesophagitis and benign oesophageal strictures are often missed in cats because awareness of the problem is low, the clinical signs are not unique and the diagnosis typically requires more than plain radiographs and routine clinical pathology testing. The true incidences  of oesophagitis and benign strictures are unknown but a busy practise should expect to see a few cases each year. Because oesophagitis often is not suspected  and consequently is not treated in timely fashion, strictures can occur and make management more expensive and complicated.

Oesophagitis can cause a wide spectrum of clinical signs. Cats with mild oesophageal inflammation may simply spit up food and/or phlegm from time to time. Usually the expelled matter contains no hint of blood. More severely affected cats may regurgitate everything they eat and can experience so mucho oesophageal pain that they are reluctant to eat. Sometimes oesophagitis can be so excruciatingly painful that patients do not even swallow saliva. In the latter cases, spontaneous gulping movements may provide an important clue about the possible presence of oesophagitis. The clinician typically does not expect to see fever or a high peripheral white blood cell count, but such changes could occur.

Upper endoscopy image of a 40-year-old male presenting with a history of chronic heartburn and solid-food dysphagia, showing coarse concentric rings throughout the entire length of the oesophagus (resembling the feline oesophagus), suggesting eosinophilic esophagitis
Barium swallow of the oesophagus, showing multiple rings associated with eosinophilic esophagitis.	Proximal oesophageal biopsies of eosinophilic esophagitis.

Although aspiration pneumonia is a possible complication of any oesophageal disease, it apparently is not as common in cats with oesophagitis compared with those with megaoesophagus. Megaoesophagus typically is most expected in dogs with oesophagitis but can be seen in some cats with this disease.

Oesophagitis usually is caused by foreign objects that have lodged in the oesophagus (e.g. hairballs), improper administration of caustic medications (e.g. tetracyclines), gastroesophageal reflux, and excessive vomiting from any cause (especially gastric outflow obstruction). Although cats have more discriminating eating habits and do not suffer from oesophageal foreign objects as frequently as dogs, hairballs expelled from the stomach and lodged in the oesophagus are a potential problem. Hairballs can be abrasive to the oesophageal mucosa and cause significant trauma. The hairball can remain in the oesophagus, eventually be regurgitated, or migrate back down to the stomach. The history can be misleading without careful determination of whether the cat is vomiting or regurgitating, Unfortunately, some feline vomiting caused by gastric or intestinal disease looks exactly like textbook regurgitation. However, if the act sounds like it changed from periodic vomiting to more constant regurgitation, the clinician should be suspicious of oesophagitis.

Pills and capsules can lodge in the oesophagus for minutes or more than an hour if they are not followed by water or food. These pills can lodged anywhere, but the cervical oesophagus appears to be the most common site. Administration of caustic medications, tetracyclines in particular, seem to be a significant cause of oesophagitis in cats. Tetracyclines, including doxycycline, are used commonly in cats. Indeed, the axiom 'no pet should die without the benefit of steroids' has been replaced with 'no pet should die without the benefit of doxycycline.' However, tetracyclines are not the only drug with the potential to cause problems. NSAIDs can do likewise, and many others probably could be responsible, including capsules and non-coated tablets. Finally, caustic substances licked off their fur (e.g. benzalkonium chloride in shampoos) also can be responsible.

Repeated or prolonged exposure of the oesophageal mucosa to gastric acid can cause oesophagitis. Anecdotally, the feline oesophagus seems more sensitive to the adverse effects of gastric acid than the canine oesophagus. Gastric outflow obstruction can cause repeated vomiting of large amounts of gastric acid which ultimately produces megaoesophagus., ostensibly resulting from oesophagitis caused by repeatedly bathing the oesophagus with the large volumes of gastric acid. Resolution of the gastric outflow obstruction in affected cats may be associated with disappearance of the megaoesophagus.

Spontaneous gastroesophageal reflux is documented poorly in cats, although hiatal hernias seem a likely potential cause. Although many hiatal hernias are asymptomatic, some are associated with substantial gastroesophageal reflux. In distinction, intraoperative gastroesophageal reflux is known to happen. It is a rare albeit important cause of oesophagitis. Uncommon, unpredictable, and not immediately obvious, its significance to the clinician centres on the fact that it is iatrogenic, brought on by anaesthesia for surgery. Therefore, it often is considered the veterinarian's fault. If a patient has a poor appetite within 1-2 days of any anaesthetic procedure, and especially if the patient starts to regurgitate / vomit during that time, iatrogenic oesophagitis could be the cause. If oesophagitis has occurred during anaesthesia, early detection and treatment are paramount to make a favourable outcome more likely and easier to obtain.

Diagnosis

A complete blood count and serum biochemistry profile typically show nothing of significance unless it is from the primary cause of the vomiting. Plain thoracic radiographs usually are normal, although megaoesophagus may be seen in some cats. Contrast radiographs may reveal very subtle changes (e.g. excessive barium retained on the oesophageal mucosa) or obvious oesophageal weakness. Fluoroscopy sometimes reveals decreased oesophageal function but it can be subtle in some affected cats.

In most cases, diagnosis is based upon the endoscopic appearance of the oesophageal mucosa, which usually is red, friable and roughened. In many affected cats, spontaneous bleeding or haemorrhage is seen after routine contact between the surface of the endoscope and the oesophageal mucosa., something that is absolutely not expected in an otherwise normal feline oesophagus. Hiatal hernias can be subtle, and the clinician should examine the lower oesophageal sphincter carefully from the orad and aborad sides. This involves retroflexing the tip of the scope in the stomach to examine the fundus and cardia in detail.

In some cases, oesophageal mucosal biopsy may aid in diagnosis. How frequently biopsy is required for diagnosis of feline oesophagitis in unknown. Biopsy of the oesophageal mucosa with a flexible endoscope is more difficult than biopsy of gastric or intestinal mucosa. The smooth muscle portion of the oesophagus usually can be biopsied with flexible endoscopes (assuming a forceful grasp of the mucosa). However, normal feline cervical oesophagus can be impossible to biopsy with a flexible endoscope. The stratified epithelial mucosa of the cervical oesophagus and the difficulty in grasping a fold of mucosa in this region make it difficult to obtain a diagnostic piece of tissue, unless substantial disease is present. Older biopsy devices (e.g. Rubin tube) obtain oesophageal mucosa reliably but they are seldom used.

Treatment

When oesophagitis is found, the clinician first should determine the reason for its presence instead of its method of treatment. If an untreated, underlying cause exists, all the medications administered are likely to be wasted. A complete upper gastroduodenoscopy with multiple gastric and duodenal biopsies is mandatory unless a cause is obvious (e.g. mass at pylorus). Even if a foreign body is found, it is still wise to biopsy the stomach and duodenum. Although almost all gastric foreign bodies in vomiting cats are the cause of vomiting, we occasionally see foreign bodies present that are not causing  any problems. In case of any doubt, biopsies obtained from a patient can be stored until it becomes obvious whether the vomiting will stop after removal of the foreign body.

Treatment consists of removal or treatment of the cause, if known and then protection of the denuded oesophagus from any further exposure to gastric acid. Once oesophagitis is present, normal oesophageal function likely can be sufficiently disrupted so that the lower oesophageal sphincter tone is lessened, which predisposes to gastroesophageal reflux. This decrease in lower oesophageal tone apparently can then initiate a positive feedback cycle in which inflammation leads to disrupted motility, which allows reflux of acid into the oesophagus, which makes the inflammation worse, which makes the motility worse, and so on. Although gastric mucosa is somewhat resistant to the effects of gastric acid, denuded oesophageal mucosa is exquisitely sensitive to even minute amounts of acid. 

Use of antacid drugs to minimise gastric acid production is referred to as chemical clearance. Histamine-2 receptor antagonists (H-2 RAs) such as cimetidine, ranitidine and famotidine are used commonly for this purpose. They are helpful drugs; however, they are competitive inhibitors of gastric acid secretion. The fact that they are competitive as opposed to non-competitive means that although they lower gastric acid secretion, they are minimally effective at abolishing it. Many cats can be treated successfully with H-2 RAs. The H-2 RAs are relatively inexpensive and can be administered parenterally, a distinct advantage in treatment of a vomiting / regurgitating cat. However, some cats require greater gastric acid suppression than is possible with H-2 RAs.

Because proton-pump inhibitors (PPI) are non-competitive gastric acid suppressants, they usually are more effective than H-2 RAs at healing oesophagitis. The PPIs generally must be administered orally, which can be a disadvantage. Therefore, PPIs generally are reserved for the more severely affected patients or those that have resisted the effects of H-2 RAs. These patients often have gastrostomy tubes inserted, which eliminates problems associated with administration of oral medications to regurgitating patients. Omeprazole  (Amcimax / Losec) is not approved for use in cats, but it has been used for this purpose. Since Omeprazole has become an over-the-counter drug, its cost has decreased. A typical dose is 0.7 mg/kg PO 24hrs (approx 5mg / cat /day). Anecdotal reports exist for using Lansoprazole but no dose has been established.

Volume clearance means keeping the stomach empty of all secretions. Gastric fluid contains digestive enzymes that could potentially delay healing of denuded oesophageal mucosa. Volume clearance is best accomplished by stimulating normal gastric outflow via the pylorus with prokinetic drugs. Formal studies of the efficacy of prokinetics in cats with oesophagitis are lacking, but such drugs are beneficial in affected humans. Metoclopramide is the most commonly used prokinetic drug in cats and has a long track record of safety. Cisapride is considered a more effective gastric prokinetic than metoclopramide and it tightens the lower oesophageal sphincter, an action that helps prevent gastroesophageal reflux. No longer marketed for human medicine, many veterinary pharmacies that compound drugs can provide it if given a prescription. Although cisapride is a more effective gastric prokinetic than metoclopramide, it must be given orally. Ranitidine has some prokinetic effects, but how they compare to metoclopramide and cisapride in cats is unclear.

In severely affected patients, especially in those that continue to regurgitate or those that refuse to eat, endoscopic placement of a gastrostomy tube feeding tube is often helpful. Such a tube allows adequate nutritional support in addition to a means of medication administration (e.g. Omeprazole, cisapride, H-2RAs and metoclopramide) when the patient goes home and is treated by the client. If such a tube is placed, the clinician  should seek to minimise further trauma to the oesophagus during the placement procedure. Esophagostomy and pharyngostomy tubes should not be used in these circumstances, because have the feeding tube in contact with the eroded oesophageal mucosa probably impedes healing.

The use of corticosteroids in these patients is controversial. Although it makes intuitive sense that administration of corticosteroids decreases inflammation and thereby lessens the risk of subsequent stricture formation, no positive proof exists that this occurs in human patients with severe oesophagitis from corrosive injury. Empirical use of corticosteroids typically is reserved for cats with especially severe oesophagitis in which the risk of stricture is deemed great enough to take whatever steps might prove useful. Typically, the use of antiinflammatory doses of dexamethasone (0.11mg/kg) given parenterally every 2-3 days.

Sucralfate slurries or suspensions have been used in these affected cats in the hope that they would be as helpful for oesophageal erosions as they are for gastric erosions. The efficacy of carafate for oesophagitis is unknown, but no benefit has been seen in humans with severe oesophagitis. Using carafate makes intuitive sense. Seemingly, carafate should be helpful in cases of gastroesophageal reflux, because reflux results in gastric acid present in the oesophageal lumen, a prerequisite for carafate attaching to eroded mucosa. Antibiotics have also been used in these patients but their efficacy is unproven.