Gastric Dilation and Rupture - Horse

The most common cause of gastric dilatation in horses is excessive gas or intestinal obstruction. Gastric dilatation may be associated with overeating fermentable feedstuffs such as grains, lush grass, and beet pulp. Presumably the large increase in production of volatile fatty acids inhibits gastric emptying. If untreated, gastric dilatation associated with overeating can rapidly lead to gastric rupture. If intestinal obstruction is the cause, the obstruction most often involves the small intestine. The fluid from the obstructed small intestine accumulates in the lumen of the stomach, causing dilatation of the stomach and retrieval of gastric reflux on passage of the nasogastric tube. Gastric dilatation also may develop in some horses with certain colonic displacements, most notably right dorsal displacement of the colon around the cecum (see Cecum and Large Intestine). It is presumed that the displaced colon obstructs duodenal outflow. Gastric dilatation with fluid also is a characteristic of proximal enteritis-jejunitis. Rupture of the stomach is a fatal complication of gastric dilatation. The stomach generally tears along its greater curvature. About two-thirds of all gastric ruptures occur secondary to mechanical obstruction, ileus, and trauma; the remaining cases are due to overload or to idiopathic causes. Clinical signs associated with gastric dilatation include severe abdominal pain, tachycardia, and retching. The mucous membranes may be pale. Classically, these acute signs are replaced by relief, depression, and toxemia after the stomach has ruptured. The prognosis for survival may be excellent in most cases of gastric dilatation, but gastric rupture is fatal. (Merck)