Recognizing and treating esophageal disorders in dogs and cats
Although esophageal disorders are less common than gastrointestinal diseases, they are not as rare as some practitioners think. Unfortunately, esophageal disorders may often be overlooked since regurgitation, a sign of esophageal disease, closely mimics vomiting, which is more common and is associated with gastrointestinal disease. This article describes how to distinguish regurgitation from vomiting and how to diagnose and treat several common esophageal disorders.
DIFFERENTIATING BETWEEN REGURGITATION AND VOMITING
Vomiting animals usually have prodromal signs (e.g. salivation, licking of lips, pacing) followed by vigorous abdominal contractions. Bile may be seen in the vomitus. But keep in mind that there is a wide range of presenting signs, and some animals that appear to be vomiting may be regurgitating and vice versa.A common assumption is that regurgitation occurs soon after eating. While this is true in some instances, many dogs will regurgitate hours, or even days, after eating. Conversely, dogs may vomit within minutes of eating.
In addition, observing partially digested material does not necessarily imply vomiting has occurred. Food that has sat in a dilated esophagus with saliva and water for a day or two may look partially digested to many owners.
Moreover, rather than asking a client if bile was present, instead ask if there was any obvious color to the ejected material, because the client may not be familiar with the term bile. If a patient throws up in your clinic, quickly determine the pH of the material with a urinary dipstick. This test will also determine if bilirubin is present. A pH of 5 or less indicates the presence of gastric acid (and hence, vomiting). A positive reaction for bilirubin confirms the presence of duodenal contents. In both instances, the patient is almost always vomiting. Finding a higher pH and a lack of bilirubin strongly supports regurgitation.
If, after obtaining a history and conducting a physical examination, you still cannot determine whether vomiting or regurgitation is occurring, then first look for esophageal disease by obtaining plain thoracic radiographs. If more detailed information is needed, you may perform contrast radiography (or better yet, fluoroscopy) or endoscopy. If plain and contrast radiographic findings of the thorax and esophagus are normal, then vomiting is most likely.
Cases of suspected vomiting due to gastrointestinal diseases primarily require investigating the abdomen. Performing a complete blood count and serum chemistry profile is recommended initially, as is performing abdominal imaging (e.g. radiography, ultrasonography). A final diagnosis may require endoscopy or surgery.
Once you firmly establish that a patient is regurgitating, you must pinpoint the particular esophageal disorder. Esophageal diseases can be congenital or acquired. They may be due to weakness (e.g. myasthenia gravis), an obstruction (e.g. foreign body), or reflux (e.g. esophagitis). Although clinical signs of congenital esophageal disease typically appear when patients are young, the disease may not be diagnosed in some patients until they are several years old.
Distinguishing esophageal weakness from esophageal obstruction is usually best done with radiography. Plain radiographs may be sufficient, but contrast radiography with oral barium administration is much more definitive and helps prevent diagnostic errors. Always obtain plain radiographs before contrast radiographs because, in many cases, plain radiographs are definitive or show that endoscopy is the best next step instead of contrast radiography (e.g. in cases of an esophageal foreign body).
Congenital esophageal weakness and congenital obstruction (e.g. vascular ring anomaly) will not be discussed here in detail because they are reasonably straightforward to diagnose. Keep in mind that vascular ring anomalies may be first diagnosed in older pets1 (i.e. more than 3 years old) or only after a foreign object obstructs the narrowed esophageal lumen. It can be easy to confuse segmental esophageal weakness proximal to the heart with a vascular ring anomaly causing obstruction. Sometimes this mistake is not recognized until the time of surgery. It is also worth noting that while surgery is indicated for vascular ring anomalies and the condition of most patients improves substantially with surgery,2 occasionally patients do not benefit from surgery.
Acquired esophageal weakness is also well-understood and has been discussed in detail elsewhere,3 but I want to emphasize two points. First, always look for a cause (e.g. localized myasthenia gravis, hypoadrenocorticism) rather than simply initiating supportive or symptomatic dietary modification. Treating the underlying cause of a megaesophagus results in a much better prognosis than simply altering the feeding practices and hoping that aspiration does not result. Second, aspiration pneumonia is the main cause of morbidity and mortality in patients with esophageal disease, especially in those with esophageal weakness. Aspiration may occur weeks or months before regurgitation is first noticed. Your index of suspicion for esophageal weakness should be high in patients with recurrent pneumonia or chronic cough even without a history of regurgitation, vomiting, or dysphagia. In these cases, esophageal function should be assessed by fluoroscopic barium contrast esophagograms so proper treatment of underlying esophageal weakness can be attempted. Remember, canine pneumonias are generally not spread from dog to dog (unless caused by Bordetella bronchiseptica), so always look for the cause, most commonly either fungal infection or aspiration.