Recognizing and treating esophageal disorders in dogs and cats - Veterinary Medicine
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Recognizing and treating esophageal disorders in dogs and cats
Esophageal disease is not as rare as you might think, but the signs are often subtle and the clues are often misconstrued.


VETERINARY MEDICINE


Esophagitis

Esophagitis is probably more common than practitioners think. Diagnosing it is problematic, because a) the clinical signs vary tremendously, depending on its severity; b) it can be hard to definitively diagnose radiographically; c) endoscopy is the best method of diagnosis, but not all practitioners have access to endoscopy; and d) it may not always be on practitioners' lists of differential diagnoses.6

Common causes of esophagitis include ingestion of caustic substances (including prescribed medications), excessive vomiting of acidic gastric contents, acid reflux, and trauma from foreign objects (previously discussed).

Common caustic substances responsible for esophagitis include oral administration of tetracycline and doxycycline monohydrate. In particular, failure to wash down a pill or capsule with water is commonly associated with retention of the pill in the esophagus for minutes to hours after administration. This retention is particularly common in cats.7 Esophagitis may result when cats lick caustic substances, such as disinfectants and cleaning agents, from their fur. In such cases, glossitis and stomatitis may alert you to possible esophageal inflammation.

Perhaps the most common cause of esophagitis is repetitive vomiting (e.g. in cases of parvoviral enteritis in dogs or gastric outflow obstruction in cats). Puppies with parvoviral enteritis may appear to have recovered from the disease, but continue to throw up. On closer examination, the vomiting is actually regurgitation. Diagnosing megaesophagus in cats should lead you to question whether repeated bouts of vomiting have resulted in the megaesophagus secondary to esophagitis.

Gastroesophageal reflux may be caused by hiatal hernias, especially in Shar-Peis. Radiography is a specific but insensitive means of detecting hiatal hernia. Endoscopic examination is more sensitive, but experience is required to recognize the lesion.

Perhaps the most worrisome cause of esophagitis secondary to gastroesophageal reflux is anesthesia. Some patients anesthetized for even the most routine procedures, such as spaying or neutering, will unpredictably experience severe gastroesophageal reflux during anesthesia.8,9 The problem is clinically silent when it occurs, but these patients typically have a poor appetite or anorexia immediately after surgery and in the days after surgery. This subtle sign is a first ripple in what can figuratively become a tidal wave. When esophageal inflammation persists, severe stricture can result.

Radiographic findings caused by esophagitis are usually subtle, although some cats will develop megaesophagus. Even a barium esophagogram may show relatively modest changes that most practitioners will miss (e.g. minor retention of barium on the mucosal surface or modest retention of barium in the esophagus). Esophagitis is best diagnosed endoscopically. It often appears as obvious inflammation, as evidenced by hyperemia and bleeding. If the esophageal mucosa bleeds during routine endoscopy, esophagitis must be highly suspected. In rare cases, there may be a pseudomembrane on the surface of the esophagus, but this is usually obvious. Esophageal biopsy may reveal some cases of esophagitis missed by gross examination, but it is difficult to obtain a biopsy sample from the esophagus (except when there is acute inflammation or a tumor), so endoscopic esophageal biopsy samples are seldom obtained. For the above reasons, the incidence of esophagitis is unknown.

The lesions of esophagitis can be mild, moderate, or severe. Severe esophagitis can affect esophageal motility to the point that gastroesophageal reflux results. The condition tends to worsen because of the establishment of a positive feedback loop (i.e. the esophagitis has caused laxity of the lower esophageal sphincter, which has allowed gastroesophageal reflux, which worsens the esophagitis, which ultimately results in more reflux). The crux of the problem is that while the stomach is accustomed to acid, a damaged esophagus is not. Amounts of acid that would be negligible for the stomach may perpetuate and worsen esophageal ulceration or erosion. Because of this cycle, it is important to shut down gastric acid secretion as completely as possible (i.e. chemical clearance). The proton-pump inhibitors (e.g. omeprazole) more effectively suppress acid secretion than do the H2 receptor antagonists such as famotidine. A disadvantage of omeprazole, however, is that it is only available in an oral preparation.10

It is also important to treat esophagitis by administering promotility agents, which cause volume clearance (i.e. forcing gastric secretions such as pepsin into the duodenum instead of allowing them to reflux into the esophagus). While metoclopramide is useful, cisapride seems much more effective. Although cisapride has been taken off the human medical market, it is available through veterinary compounding pharmacies. Once again, a principal disadvantage is that cisapride must be given orally. However, if a gastrostomy tube has been placed, then oral medications may be administered through the tube, bypassing the esophagus.

Gastroesophageal reflux may occur in the absence of obvious causes such as chronic vomiting or a hiatal hernia, but the incidence of such causes is unknown. Hiatal hernias can result in regurgitation or esophagitis and can be particularly difficult to diagnose. Many times, fluoroscopic examination is required. However, many normal dogs will have an occasional reflux during a barium esophagogram. Making a confident diagnosis of gastroesophageal reflux requires observing multiple episodes of reflux during a barium esophagogram.

Benign esophageal stricture

A common result of poor or no treatment of esophagitis is esophageal cicatrix causing a stricture.6 The principal points to remember about cicatrices are a) they are usually partial, such that administration of liquid barium may or may not reveal them, even if fluoroscopy is used; b) it is far easier to prevent a benign stricture than to resolve a serious one; and c) ballooning and bougienage are the preferred ways to treat strictures.11,12 Esophageal surgery should be avoided if at all possible.

Although ballooning has been touted as being superior to bougienage, experience in human medicine suggests that either can be effective, provided that the operator has been trained well. The goal is not necessarily to return the patient to a state of normalcy, but to make the pet functional, even if that means the diet must be softened. Some patients will only need to have their stricture dilated once or twice, while others will require dilation two or three times a week for up to 20 times. Ballooning should by performed only by those trained in the technique.

Various adjunct medical management schemes have been tried to make the procedure more effective sooner, including systemic and intralesional corticosteroids.13 At this time, there are no data showing that corticosteroid administration enhances success of esophageal dilation in dogs or cats. Some benefit may result from using electrocautery snares and knives to make a three- or four-quadrant set of cuts into dense strictures before dilation is attempted. The idea is that by making such cuts, dilation will result in a more even set of breaks in the cicatrix instead of one deep break that may then heal and form an even worse stricture. My experience is that more than 80% of patients will become functional, if the clinician is allowed to balloon as often as is needed.


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Source: VETERINARY MEDICINE,
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