Distinguishing regurgitation from vomiting

Regurgitation is the expulsion of material (i.e., food, water, saliva) from the mouth, pharynx, or esophagus. It must be differentiated from vomiting (the expulsion of material from the stomach and/or intestines) and expectoration (the expulsion of material from the respiratory tract). Historical and physical examination findings sometimes allow these three to be differentiated. Expectoration is generally associated with coughing at the time of the event. Animals that regurgitate and occasionally those that vomit may cough as a result of aspiration, but oral expulsion is not consistently related with coughing.

Some animals that appear to be regurgitating are vomiting and vice versa. If one cannot distinguish between the two on the basis of the history and physical examination findings, one may use a urine dipstick to determine the pH and whether there is bilirubin in freshly ”vomited” material. If the pH is less that 5, the material has originated from the stomach and probably resulted from vomiting. If the pH is more than 7 and there is no evidence of bilirubin, this is consistent with regurgitation. The presence of bilirubin indicates the material has originated from the duodenum (i.e., vomiting). A positive finding of blood in the urine dipstick test is not useful.

If vomiting and regurgitation still cannot be distinguished, plain and/or contrast-enhanced radiographs will usually detect any existing esophageal dysfunction. However, some esophageal disorders (e.g., hiatal hernia, partial stricture) are easily missed unless a careful radiographic technique is used.

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