This syndrome is also called GDV. All of these are associated with a
condition in which the dog's stomach distends with air, rotates
within the abdominal cavity causing the stomach and splenic vessels
to occlude resulting in shock and possibly death.
How or why does this occur?
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. Currently, the theory is that the
stomach's contractions lose their regular rhythm and trap air in the
stomach; this can cause the twisting event. Dogs may undergo
several bouts of "partial" torsion where the stomach doesn't fully
twist before it completely flips. The complete process, however,
defies a good explanation.
How is it diagnosed?
This condition usually occurs in deep-chested dogs of large breeds.
Some of the more commonly affected breeds include Great Danes,
Irish Setters, German Shepherds, Standard Poodles, Rottweilers,
Golden/Lab Retrievers and Afghan Hounds. Dogs may initially drool
excessively; make frequent attempts to vomit with or without
producing anything. The owners may notice that the stomach is
distended with air. An enlarged stomach will cause the abdominal
wall to protrude prominently, especially on the dog's left side. If the
dog has torsed, the distention will be on the RIGHT 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. The dogs may or may not be painful but will be very
depressed. It may lie in what is commonly called a "praying
position" with the front legs drawn fully forward. 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.
What happens when the stomach is distended with air?
The first process that occurs is an occlusion of blood flow to a
portion of the stomach and spleen. 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.
What is done to save the dog's life?
Several important steps must be taken quickly.
The initial 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.
Relieving the pressure from the stomach is next attempted. 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 (ECG) is the best method for monitoring the
heart's rhythm.
What is the survival rate?
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 to 70% of the dogs will survive.
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. Various
dietary and exercise restrictions have been used, but none of these
has proven value.
Craig Ritchie, DVM
Bellevue, Washington
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