What is Bloat and Why Does it Kill Dogs So Quickly

Bloat in layman’s terms = the stomach has flipped:
Bloat in dogs is likely caused by a multitude of factors, but in all cases the immediate prerequisite is a dysfunction of the sphincter between the esophagus and stomach and an obstruction of outflow through the pylorus, or a clog.

Once you recognize the problem know that you have an urgent medical emergency and you do not have much time to get your pet to veterinary care, surgical intervention is the only solution.

Symptoms of Bloat 
In the early stages, a dog that is “bloating” will be uncomfortable and edgy for no apparent reason.  A dog might stand uncomfortably and seem to be in extreme discomfort for no apparent reason.

It will deteriorate rapidly. In no particular order, without treatment an affected dog will become increasingly restless, painful, weak and depressed. Its abdomen typically will become swollen, firm and excruciatingly painful. It may retch and try to vomit, but those attempts will be largely non-productive. Its breathing will become rapid, shallow and difficult. Its gums and other mucous membranes will become pale to blue, and it will salivate profusely. Its pulse will weaken while its heart rate races. Ultimately, without surgical intervention, the dog will collapse and die within a matter of a few hours. The most obvious physical signs of bloat are firm distension of the abdomen (a very hard, swollen belly, tight like a drum), together with obvious abdominal discomfort. Non-productive retching and attempts to vomit are also common. Key clinical signs may include:
Firm, distended abdomen
Non-productive attempts to vomit
Retching
Restlessness
Weakness
Abdominal pain (looking at the belly, biting at it, whimpering, etc)
Depression
Lack of appetite
Rapid shallow breathing (tachypnea); difficulty breathing (dyspnea)
Profuse salivation (“frothing at the mouth”; normally indicates severe pain)
Pale mucous membranes (gums, others)
Weak pulse
Rapid heart rate (tachycardia)
Collapse
Cardiac arrhythmias (abnormal heart rhythms)
What Causes Bloat & What You Can Do To Avoid It
Some of the more widely acknowledged factors for developing bloat include increased age, breed, having a deep and narrow chest, stress, eating foods such as kibble that expand in the stomach, overfeeding, too much water consumption in a small period of time; gulping air with water intake before or after exercise.  Dogs with inflammatory bowel disease may be at an increased risk for bloat.

Breed susceptibility
Even medium size dogs get bloat but as a general rule, bloat is of greatest risk to deep-chested dogs. The five breeds at greatest risk are Great Danes, Weimaraners, St. Bernards, Gordon Setters, and Irish Setters. In fact, the lifetime risk for a Great Dane to develop bloat has been estimated to be close to 37 percent. Standard Poodles are also at risk for this health problem, as are Irish Wolfhound, Doberman Pinschers, Rottweilers, German shorthaired pointer, German Shepherd Dogs and Rhodesian Ridgebacks. Basset Hounds have the greatest risk for dogs less than 23 kg/50 lbs.

There is a fairly new preventative surgery and the cost is around $750 to $1000. Some breed specific rescue organizations will not allow adoption until this surgery has been performed.

Wiki Information
http://en.wikipedia.org/wiki/Gastric_dilatation_volvulus