Distention and twisting can occur independently of one another. But when both occur, rapid veterinary intervention is critical. When distention and twisting occur together, the result is shock (insufficient blood circulation), leading to multiple organ failure and death within a matter of hours. Most GDV fatalities result from the cascade effect of shock.
Experts estimate a 25 to 50 percent mortality rate for dogs diagnosed with GDV.
Although no one knows for sure what causes GDV, studies indicate that older purebred dogs, especially larger, deep chested breeds such as Great Dames, Irish Setters, and Saint Bernards, show a disproportionately high incidence of GDV. However, body type may be as significant a risk factor as size. Basset Hounds and Airedale Terriers, both midsized breeds, consistently appear on lists of breeds most susceptible to GDV. Preliminary studies at Purdue University's School of Veterinary Medicine indicate that dogs with a higher chest depth-to-width ratio may be at a greater risk of developing bloat. With deep, narrow chests, there's a greater opportunity for the ligaments that support the stomach to stretch, especially when the stomach is full. A loose stomach may be more prone to twisting. Puppies and mixed breeds are also at risk, especially puppies that gulp their food.
GDV usually occurs within a few hours after a dog eats a meal. Yet no single food type, ingredient, or feeding method has been shown to cause GDV. In fact, GDV seems to be multifactorial in nature. Some of the predisposing factors are known, but what exactly causes GDV is still unknown. Thus, taking food related precautions makes sense, but will not necessarily prevent bloat.
Because so much about GDV remains unknown, an owner can do everything by the book and still not escape the sometimes tragic consequences of bloat. Since there are no sure fire preventive measures, your best bet is remain alert to the symptoms, and see your veterinarian immediately should they occur. Hope this helps, and may you and your dog never have to experience this tragic event.