The incidence of gastric dilatation and volvulus is 2.4 to 7.6 for every 1,000 dogs admitted to a hospital. It is the second leading cause of canine death with 15% of dogs dying due to the condition within their lifetime.

Risk factors associated with this disease are numerous and include the following; advanced age (risk by a factor of 1), decreased number of meals fed per day, giant breed status (in urban residences, 22% of cases), large breed status (in rural residences, 24% of cases, and a risk factor of 1), having residence in the United Kingdom, being born in the 1990s, being a family pet, spending at least 5 hours a day with the owner, being an intact female, conducting exercise immediately after ingesting food, experiencing stress immediately after a meal, having an aggressive, fearful, or anxious temperament, having a history of gastric dilatation and volvulus in a first degree relative, having a history of a splenic torsion or splenectomy (3 to 8% incidence), inflammatory bowel disease, increased hepatogastric ligament length, increased thoracic depth to width ratio, having a thin or lean body type, ingesting food with small particle size (less than 30 mm), ingesting a large amount of food, the spring season, ingesting moistened dry food, being fed dry kibble, feeding only one type of dogs food, feeding a commercial dog food, presence of a gastric foreign body (by a factor of 5, a 98% increase), preventing the ingestion of water before and after a meal, purebred status (by a factor of 5), and rapid eating habit. In Texas, the highest risk occurs during the months of November to January, whereas the lowest risk is seen from June to August. In Switzerland, a higher incidence is seen during warmer weather. Kenneling may also increase the risk of disease.

Those with higher body weights or advanced age are more likely to have a history of a splenectomy. Those dogs that develop gastric dilatation and volvulus without a history of splenectomy make up 1 to 6% of cases while those with a history of splenectomy make up 3 to 6% of cases. These differences may or may not be significant, but a risk factor of 5.3 has been reported in those dogs that have a history of splenectomy that develop gastric dilatation and volvulus. Those with a history of splenectomy develop gastric dilatation and volvulus 350 days post-operatively and tend to be intact male (25% of cases). The percentage of dogs that develop gastric dilatation and volvulus after having received a splenectomy in the past after 1 year, 3 years, and 6 years are 65%, 20%, and 15% respectively. The percentage of dogs that do not develop gastric dilatation and volvulus after having received a splenectomy in the past after 1 year, 3 years, and 6 years are 50%, 30%, and 20% respectively. The difference is not significant.

Risk factors associated with a decreased risk include having a happy or easy-going temperament, playing with other dogs, being neutered, running the fence after a meal, being given fish or egg diet supplements, being submissive to dogs and people, spending the same time indoors and outdoors, winter seasons, being female, ingesting table food in addition to dry food, and attending dog shows.

Canine breeds reported to be at a higher risk include the Airedale terrier, Akita, Basset Hound, Borzoi, Bull Mastiff, Chow chow, Collie dog, Doberman pinscher (4% incidence), Gordon Setter, Great Dane (11% incidence, 42% life-time risk), German Shepherd dog (12% incidence), Irish Setter, Irish Wolfhound, Saint Bernard, Rottweiler (4% life-time risk), Standard Poodle (5% incidence), and Weimaraner. Overall life-time risk ranges from 5 to 40% with a cumulative risk of 5%. Males, older dogs (dogs that are 6 to 7 years of age are twice as likely to be affected than those 3 to 4 years of age), and dogs with higher body weights are over-represented.

The pathophysiology of the condition involves two theories. The first is that gastric rotation happens initially followed by gastric dilatation. The second theory is that gastric dilatation happens initially, perhaps due to rapid ingestion of food or inhalation of air, followed by gastric rotation. In either scenario, the stomach rotates about its long axis in a clockwise direction, the pylorus and proximal duodenum displaces ventral and cranial, from right to left, finally positioned dorsal to the esophagus. The gastroesophageal sphincter is obstruction and pyloric dysfunction is evident. Experimentally, the intragastric pressure during gastric dilatation and volvulus becomes 9 to 62 mmHg due to the mechanical obstruction. The hepatoduodenal ligament stretches and the stomach folds. The gastrosplenic and hepatoduodenal ligaments may also become involved. Eructation, vomiting, and pyloric outflow is inhibited, resulting in aerophagia, bacterial fermentation, and rapid gas buildup and progressive gastric dilatation.