What is meant by the term "Canine Bloat"?
This is a term that is synonymous with the more scientific term "Gastric Dilatation/Volvulus." It is often called GDV. That means that a dog's stomach twists on its long axis and distends with air to the point where the dog goes into shock and may die.
Dilatation means that the stomach is distended with air, but it is located in the abdomen in its correct place (has not twisted). Volvulus means that the distention is associated with a twisting of the stomach on its longitudinal axis.
How or why does this occur?
We really do not know the answer to either of these questions. Original theories suggested that it occurred when a dog ate a large meal and then engaged in strenuous exercise. However, there is no scientific evidence to support this theory. In most cases, the cause is undeterminable. No specific diet or dietary ingredient has been shown to lead to bloat.
The most commonly affected breeds are those that are “deep-chested,” meaning the length of the chest is relatively longer in proportion to its width. Examples of deep-chested breeds are Great Danes, Setters, Boxers, and Greyhounds. Studies have proven that purebred dogs are more than 3 times more likely to bloat than mix-breed dogs.
Why is it so serious?
When the stomach becomes excessively distended, it causes severe abdominal pain. When the stomach twists, it cuts off its own blood supply as well as the escape routes for the trapped air. Often, the twisting of the stomach leads to rotation of the spleen and compromise to its blood flow. Furthermore, the size and location of the enlarged stomach reduces return blood flow to the heart leading to shock and death if untreated.
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 that 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.
Another complication is cardiac arrhythmia. This abnormal heart rhythm occurs when the heart is deprived of an adequate blood flow and some of its cells begin to die. Dogs must be monitored carefully for this complication. If it occurs and is not treated, it can be fatal.
How can I tell if my dog has bloat?
Your dog‘s abdomen will likely become taut and distended. This is usually visible near the ribs, but depends on the dog’s conformation. The dog may appear depressed and/or painful, and often adopts a “praying position” with the front legs extended fully. The biggest clue is that your dog may have “dry-heaves.” The dog retches continuously, but no vomit is produced. This indicates a life-threatening emergency and your dog should be brought to the hospital immediately.
How is Bloat diagnosed?
The first step is to establish that the stomach is distended with air. The presence of a rapidly developing distended abdomen in a large breed dog is often enough evidence to make a tentative diagnosis of GDV. A radiograph (x-ray) is used to confirm that the diagnosis is dilatation. In most cases, it can also identify the presence of volvulus. Some dogs experience a chronic form of the disease in which the stomach is partially twisted. Distention with air does not occur because the partial twist permits air that accumulates to be expelled out the mouth or into the small intestines. Repeated vomiting is the most common sign. It is diagnosed with radiographs (x-rays) of the stomach that show an abnormal shape to the stomach.
What is done to save the dog's life?
There are several important steps that must be taken quickly.
1) 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.
2) Pressure must be removed from within the stomach. In some cases, this may be done with a tube that is passed from the mouth to the stomach. However, if the stomach is twisted, the tube cannot enter it. Instead, a large bore needle is inserted through the skin into the stomach and the trapped air is released. 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.
3) The stomach must be returned to its proper position. This requires abdominal surgery that can be risky because of the dog's condition.
4) The stomach wall must be inspected for areas that may be dead due to compromised blood supply. Although this is a very bad prognostic sign, these area(s) of the stomach should be surgically removed. The spleen must also be assessed for viability, and a splenectomy may be necessary.
5) The stomach must be attached to the abdominal wall (gastropexy) to prevent recurrence of GDV. This procedure greatly reduces the likelihood of recurrence, but does not completely eliminate it.
6) 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 (ECG) is the best method for monitoring the heart's rhythm.
What are the survival and recurrence rates?
These are largely determined by the severity of the distention, the degree of shock, how quickly treatment is begun, and the presence of complications, especially those involving the heart. Approximately 60 to 70% of dogs survive. This survival rate drops drastically to approximately 20% if surgery is not performed. Following successful surgery, the recurrence rate is 6%. Approximately 75% of dogs that do not undergo surgery have another bloat episode.
What can be done to prevent it from occurring again?
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.