Regurgitation is the relatively effortless expulsion of undigested food, without retching. It occurs because the esophagus is physically blocked or because it lacks peristaltic activity. In either case, the food accumulates until the esophagus is overloaded, after which the food is passively expelled.
Regurgitation should not be confused with vomiting. Vomiting is the forceful expulsion of stomach contents, preceded by drooling and retching. The material vomited is usually sour smelling, partly digested, and stained with yellow bile.
The sudden onset of regurgitation in a previously healthy dog is almost certainly due to a foreign body caught in the esophagus. Constant drooling indicates that the dog cannot swallow saliva.
Chronic regurgitation (the kind that comes and goes but seems to be getting worse) suggests a partial obstruction caused by megaesophagus, stricture, or tumor.
A serious complication of regurgitation is aspiration pneumonia, in which the lungs become infected as a result of food being aspirated into them. When regurgitated food ends up in the lungs, aspiration pneumonia is the result. Another potentially serious complication is nasal cavity infection. This occurs when food is regurgitated into the nose.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.