Bloat
Copyright
©1996 HomeVet
What
Is Meant by the Term 'Bloat' in Dogs?
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 distends with air,
twists and cuts off blood flow, to the point that 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. Volvulus means
that the distention is associated with a twisting of
the stomach on its longitudinal axis.
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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.
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.
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How
Is It Diagnosed?
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.
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What
Happens When the Stomach Is Distended With Air?
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.
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What
Is Done to Save the Dog's Life?
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.
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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 percent to 70
percent of the dogs will survive.
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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 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.
Prevent obesity.
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 meant to supplement
that provided by your veterinarian. Nothing can replace
a complete history and physical examination performed
by your veterinarian. - Dr. Jeff
I greatly value your feedback. Please let me know what
you think of this site and what you would like to see
on it. drjeff@homevet.com
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Last modified
at 11:07 PM on 12/14/98.
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