Dilatation means that the stomach is distended with air, but it is located in the abdomen in its correct place. Volvulus means that the distention is associated with a twisting of the stomach on its longitudinal axis.
We really do not know the answer to either of those questions. Original theories suggested that it occurred when a dog ate a large meal of dry food and then drank a lot of water. The water caused the dry food to swell. At the same time, the dog was supposed to be engaged in strenuous exercise that included running and jumping. That resulted in the dog's stomach twisting on itself as the heavy organ was jostled about in the abdomen.
Although that is the most common explanation given, there is no scientific evidence to support this theory. In most dogs experiencing GDV, the stomach is not excessively full of dry food and the dog has not recently engaged in strenuous exercise. The most current theory is that the stomach's contractions lose their regular rhythm and trap air in the stomach; this can cause the twisting event. However, the sequence of events for most cases defies a good explanation.
The first step in diagnosis is to determine if the correct breed is involved. This condition almost always occurs in deep-chested dogs of large breeds. Some of the more commonly affected breeds include Great Danes, Irish Setters, German Shepherds, and Afghan Hounds.
The next step is to establish that the stomach is distended with air. An enlarged stomach will cause the body wall to protrude prominently, especially on the dog's left side. The swelling will be very firm and obvious enough to see across the room. Occasionally, this distention is not very apparent. This occurs in dogs which have a large portion of the stomach up under the rib cage. In most cases, however, the owner is able to detect the distention. A dog which experiences significant pain will be very depressed. It may lie in what is commonly called a "praying position" with the front legs drawn fully forward. This should occur quickly, within two to three hours at the most.
The presence of a rapidly developing distended abdomen in a large breed dog is enough evidence to make a tentative diagnosis of GDV. A radiograph (x-ray) is used to confirm the diagnosis of dilatation. It can also identify the presence of volvulus, in most cases.
The first major life-threatening event that occurs is shock. This occurs because the distended stomach puts pressure on the large veins in the abdomen that carry blood back to the heart. Without proper return of blood, the output of blood from the heart is diminished, and the tissues are deprived of blood and oxygen.
The reduced blood output from the heart and the high pressure within the cavity of the stomach cause the stomach wall to be deprived of adequate circulation. If the blood supply is not restored quickly, the wall of the stomach begins to die; the wall may rupture. If volvulus occurs, the spleen's blood supply will also be impaired. This organ is attached to the stomach wall and shares some large blood vessels. When the stomach twists, the spleen is also rotated to an abnormal position and its vessels are compressed.
When the stomach is distended, digestion stops. This results in the accumulation of toxins that are normally removed from the intestinal tract. These toxins activate several chemicals which cause inflammation, and the toxins are absorbed into circulation. This causes problems with the blood clotting factors so that inappropriate clotting occurs within blood vessels. This is called disseminated intravascular coagulation (DIC) and is usually fatal.
There are several important steps that must be taken quickly.
- Shock must be treated with administration of large quantities of intravenous fluids. They must be given quickly; some dogs require more than one intravenous line.
- Pressure must be removed from within the stomach. This may be done with a tube that is passed from the mouth to the stomach. Another method is to insert a large bore needle through the skin into the stomach. A third method is to make an incision through the skin into the stomach and to temporarily suture the opened stomach to the skin. The last method is usually done when the dog's condition is so grave that anesthesia and abdominal surgery is not possible.
- The stomach must be returned to its proper position. This requires abdominal surgery which can be risky because of the dog's condition.
- The stomach wall must be inspected for areas that may have lost its blood supply. Although this is a very bad prognostic sign, the devitalized area(s) of the stomach should be surgically removed.
- The stomach must be attached to the abdominal wall (gastropexy) to prevent recurrence of GDV. Although this is not always successful, this procedure greatly reduces the likelihood of recurrence.
- Abnormalities in the rhythm of the heart (arrhythmias) must be diagnosed and treated. Severe arrhythmias can become life-threatening at the time of surgery and for several days after surgery. An electrocardiogram (EKG) is the best method for monitoring the heart's rhythm.
This will largely be determined by the severity of the distention, the degree of shock, how quickly treatment is begun, and the presence of other diseases, especially those involving the heart. Approximately 60 percent to 70 percent of the dogs will survive.
The most effective means of prevention is gastropexy, the surgical attachment of the stomach to the body wall. This will not prevent dilatation (bloat), but it will prevent volvulus in most cases. Various dietary and exercise restrictions have been used, but none of these have proven value.
To avoid surgery after an occurrence of bloat (or prophylactically), the following steps should be taken to minimize the risk factors for bloat:
Feed a high quality wholesome diet with appropriate supplements.
Feed several smaller meals rather than one large one.
If you have more than one dog make sure that they are calm (to minimize swallowing air) during meals. You may have to feed them separately.
Do not feed your dog before or after vigorous exercise.
Avoid sudden diet changes. Make any major dietary changes gradually over 7-10 days.
Be aware of the symptoms (abdominal swelling and unproductive coughing/retching) if you have a deep-chested breed of dog.
Call your veterinarian or emergency clinic if you have any questions.
Please note: The information provided here is intended to supplement the recommendations of your veterinarian. Do not disregard veterinary advice or delay treatment based on information on this site. Nothing can replace a complete history and physical examination performed by your veterinarian. -Dr. Jeff
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