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Vomiting is the active expulsion of food from the stomach. Not all food that leaves the mouth has been vomited however, because sometimes it is returned without ever reaching the stomach. See
dysphagia, pharyngeal retching, and regurgitation. Immediately prior to vomiting the animal feels nauseous, then there is reflex closure of the epiglottis over the trachea to prevent aspiration of food into the lungs. Finally there is synchronised contraction of the abdominal and diaphragmatic muscles and this increased intra-abdominal pressure ejects the food out of the stomach, up the oesophagus and out of the mouth.

Vomiting is a complex reflex involving emetic centres in the medulla of the brain which can be stimulated by a variety of stimuli. The most common causes are:

Vomiting is a natural defense mechanism against ingested toxic and noxious substances so there are occasions when it would be inappropriate to inhibit the vomit reflex with therapeutic agents.

When persistent or unproductive vomiting is present it should be treated by attending to the underlying cause - if one has been identified, and/or with the use of effective antiemetic drugs such as metaclopramide

Aspiration into the windpipe or lungs is rare unless the animal has a localised problem in the region of the pharynx or larynx, such as old dogs with
laryngeal paralysis.


Last updated : October 2013