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
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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
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.
WebMD Veterinary Reference from "Dog Owner's Home Veterinary Handbook"