The guttural pouch is a unique structure of the horse consisting of 2 large blind air-filled pouches in the back of the throat (pharynx). The entrance to these pouches are 2 narrow slits in the back of the throat and the two pouches share a common wall. The equine guttural represents a out-pouching of the auditory (eustachian) tube and whose function is not clear. It has been suggested that it could act to cool the brain by ventilating and cooling the internal carotid arteries which travel in the wall of the guttural pouches. The air circulating in the pouch cools the blood which in turn cools the brain. Experiments support this possibility.

In some newborns and growing horses the opening acts as a one way valve that inflates the pouch but does not allow the air to escape. When this occurs a non-painful swelling in the throatlatch occurs either unilaterally or bilaterally. Though not often a problem itself it can cause difficult swallowing and aspiration of food and water into the lungs. This article discusses the clinical signs, diagnosis, treatment and prognosis of guttural pouch tympany.

GPT occurs predominately in foals and weanlings with fillies affected most often. Foals are usually normal at birth but may develop swelling over the first several days. Some cases do not develop until later but usually before weaning. Though it can occur in any breed Arabs, Warmbloods, and Paints may be predisposed and some lines of these breeds seem to have more trouble with it.

The cause of this disease remains unknown, but there are likely to be several causes involving problems with the opening of the guttural pouch to the pharynx:

• A congenital defect at the pharyngeal orifice specifically along the plica salpingopharyngeus.
• Inflammation of the plica salpingopharyngeus secondary to infection.

This redundant tissue may act as a 1-way valve, leading to accumulation of air in the affected pouch. Despite widespread acceptance of this hypothesis, no gross abnormalities of the pharyngeal orifice or plica salpingopharyngeus in clinically affected horses have been reported.