It can happen to any dog, but it usually happens to big dogs. It strikes males more than females, and if not treated, can kill within hours.
No one knows what causes it and no one is sure how to prevent it; there are a lot of opinions all based on anecdotal evidence, but no hard facts to go on.
Bloat, as it is commonly called, is a condition technically known as gastric dilation/volvolus, or GDV, which at first seems and is, similar to stomach gas. The abdomen becomes enlarged and distended, and the dog shows signs of discomfort – pacing, salivating, whining and trying to throw up. At this stage, a dose of Mylanta Gas, Gas-X, or any product containing simethicone may help by breaking up any gas bubbles. Not every case is extreme, and the problem may go away, but if it does not, or gets worse, it becomes a medical emergency. If the abdomen continues to swell, the pressure on the organs, especially the heart and lungs, can reduce the blood flow to the heart and spleen, damaging both organs and leading to cardiac arrest. In some cases the stomach can burst, causing peritonitis. A vet can insert a tube into the stomach to relieve the pressure, but you have to get the dog there fast. And that assumes the stomach has not flipped.
In the most serious stage, the stomach rotates partially or a full 360° on the ligaments that support it. Now the clock is really ticking. The esophagus is closed off, as is the duodenum, the upper intestine, and there is no way to release the pressure. A major vein that passes through the stomach is pinched, cutting off blood to the stomach and other organs, leading to tissue damage and destruction. Worse, blood to the heart is reduced drastically, and a heart attack is imminent if surgery to correct the problem and repair the damage is not done soon. At this point, even surgery may not save the dog.
Bloat, also called stomach torsion or twisted stomach, is the number two killer of dogs, after cancer, yet many, if not most dog owners are not familiar with it or aware how serious a problem it is. There is no direct cause and affect with this problem, such as a bacteria or virus that a vet can treat with antibiotics or vaccinate against. Bloat is usually the result of a combination of factors that might have no affect on most dogs, but can bring about a life-threatening situation in others. Owner awareness of the problem is the first step in preventing its occurrence.