Gastric dilatation-volvulus (GDV) is an acute medical and surgical condition caused by several pathophysiologic effects that occur secondary to gastric distention and malpositioning.
DILATATION OR VOLVULUS—WHICH COMES FIRST?
Stomach dilatation is caused by air, gas, and fluid accumulation. Air accumulation in the stomach is most likely caused by aerophagia. The fermentation of carbohydrate by bacteria and the production of gas in the acidic environment of the stomach contribute to gas accumulation. Ingesta, gastric secretions, and transudate from venous obstruction contribute to the accumulation of fluids in the stomach.
It is unknown if volvulus of the stomach occurs before dilatation or vice versa. Volvulus could occur first since it has been documented in some patients without gastric dilatation. Hepatogastric ligaments have been found to be significantly longer in dogs with GDV.1 With the elongation or stretching of the hepatogastric ligaments, the stomach can twist, which shows that volvulus could occur first. Volvulus will result in occlusion of the lower esophageal sphincter and the pylorus. Thus, dilatation will occur because of the fermentation of gastric content.
Gastric dilatation has been diagnosed in dogs without volvulus and in dogs that have had a gastropexy. Aerophagia is then the major cause of dilatation. When intragastric pressure increases, it likely compresses the lower esophageal sphincter against the diaphragm and interferes with its opening. Intragastric bacteria and bacterial fermentation result in further gastric distention. The distended stomach can then rotate since the hepatogastric ligaments are stretched.2-4
Although acute GDV has been recognized for many years in dogs, its exact cause is still not clearly understood—only risk factors have been identified:
Gastric factors: An increased gastrin concentration, decreased stomach motility, and delayed gastric emptying have been mentioned as risk factors but have never been demonstrated.5-8
Dietary habits: Diet, large amounts fed at each feeding, the frequency of feedings (one meal a day), a fast eating style, and exercise or stress after a meal are contributing factors for the development of GDV.5-8
Signalment and physical attributes: Large-breed dogs, dogs with a large thoracic depth-to-width ratio, underweight dogs, and older animals are at higher risk to develop GDV. Dogs with a happy personality might be at less risk.6-9
Splenectomy: The removal of a large spleen has been associated with the development of GDV in some case reports; however, studies have not proven splenectomy to be a risk factor for the development of GDV in dogs.