Distension of the stomach caused by accumulation of swallowed air, gastric secretions, gas, and food. Overeating in all small animals may result in gastric distension. Acute distension in mature animals may be due to anatomical rotation of the stomach (volvulus). Gastric dilatation-volvulus has been identified predominantly in large and giant breeds of dogs, but also has been reported in smaller dogs such as the Pekingese, Dachshund, and English Bulldog. Gastric dilatation also occurs in domestic cats, foxes, mink, wild carnivores, rabbits, nutria, guinea pigs, rats, mice, and monkeys.

Etiology: The cause of acute gastric dilatation-volvulus is unknown, although many associated factors have been incriminated. In the dog, these include anatomy (large, deep chest, stretching of gastric supportive ligaments, pendulous stomach), postprandial exercise, hereditary predisposition, splenic engorgement and rotation, pyloric sphincter dysfunction, and aerophagia. Recently it has been suggested that transplacental transfer of the effects of increased serum gastric concentrations predispose to the acute condition.

Pathogenesis: Gastric distension precedes gastric volvulus. An accumulation of gas, secretions, and food in the stomach leads to an increase in intragastric pressure and dilatation. Failure to empty the stomach results from creation of an acute angle at the gastroesophageal junction formed when the stomach is excessively distended. Aerophagia results from epigastric pain and leads to further distension. This, in turn, leads to impairment of portal venous and caudal vena caval blood flow and hypertension distal to obstruction by the stomach. Serious digestive, respiratory, cardiovascular, and nervous system disturbances ensue and cause hypovolemic shock, which, with time, may progress to endotoxic shock and death.

Clinical Findings: Historical findings are inconsistent; gastric dilatation may have been experienced previously. Usually, there is an acute onset of restlessness, epigastric pain, and excessive salivation. The cranial abdomen is distended and usually tympanic; animals retch but are unable to vomit. As the condition worsens there are variable signs of shock (tachycardia, weak peripheral pulses, pale mucous membranes, cold extremities, depressed capillary refill, and weakness). Dyspnea and hyperpnea are common.

Lesions: The stomach is large and atonic; with gastric volvulus the greater omentum is draped over the fundus. Hyperemia, venous engorgement, splenomegaly, gas-filled intestines, and gastric mucosal injury varying from hyperemia to necrosis will be seen. Occasionally, gastric perforation and peritonitis occur.

Diagnosis: Clinically, simple acute gastric dilatation cannot be differentiated from dilatation complicated with gastric volvulus. Usually the mature animal will have a large amount of air in the stomach and percussion of the cranial abdomen will result in a tympanic sound. (Passage of a stomach tube is not a diagnostic test for volvulus.) Cranial abdominal distension is always present.

Usually, the animal is treated for shock and the stomach decompressed before radiography. Radiography will frequently demonstrate gastric volvulus, in which the pylorus will move dorsally, cranially, and to the left. Soft-tissue lines across the gas-filled stomach are frequently noted. Barium sulfate may be used to better outline the position of the pylorus. Splenomegaly will occasionally be seen. Laparotomy may be required for a positive diagnosis.

Treatment: Emergency treatment is usually required. Gastric decompression and correction of shock should be done simultaneously. . . .

Since no specific etiology has been identified, control measures may not be successful. In order to promote gastric emptying, multiple small feedings are preferred over large single meals. Moistened foods and foods higher in carbohydrates or protein will empty more rapidly than high-fat-content foods. Water consumption after exercise and exercise after eating should be minimized. Clients should be told how to identify clinical signs of acute gastric dilatation and to promptly seek professional assistance.