Bloat is a medical condition in which the stomach becomes overstretched by excessive gas content. It is also commonly referred to as torsion, gastric torsion, and gastric dilatation-volvulus (GDV) when the stomach is also twisted. The word bloat is often used as a general term to cover gas distension of the stomach with or without twisting. The name comes from the Middle English blout, meaning soft or puffed, which is from the Old Norse blautr, meaning soft or soaked.Meteorism, its name derived from the writings of Hippocrates, is now rarely used in English. The condition occurs most commonly in domesticated animals, especially ruminants and certain dog breeds.

In dogs, gas accumulation in the stomach is usually associated with volvulus of the stomach, which prevents gas from escaping. Deep-chested breeds are especially at risk. Mortality rates in dogs range from 10 to 60 percent, even with treatment. With surgery, the mortality rate is 15 to 33 percent.