Issue 4
Cushing's
Disease
What is Cushing's Disease?
Cushing's Disease, technically called canine hyperadrenocorticism,
is a syndrome in which the body is producing too much cortisone.
Cortisone is produced by the body as a natural response to stress.
Different types of cortisones are produced by the adrenal glands
(located in front of the kidneys). These cortisones are vital for
normal day-to-day function. Too little of these cortisones can cause
vomiting, diarrhea, weakness, collapse and even death. However,
too much of these cortisones, as in Cushing's Disease, has adverse
effects on the body as well.
The cause of these high cortisone levels is most often (in approximately
85 percent of cases) a small tumor in the pituitary gland, located
in the brain. This small tumor sends too much hormone to the adrenal
glands, telling them to produce more and more cortisone. Less often,
Cushing's Disease is caused by a tumor in the adrenal gland, causing
it to produce too much cortisone.
How do I know if my dog has Cushing's Disease?
The symptoms of Cushing's Disease include: excessive water consumption
and increased frequency of urination; a ravenous appetite; excessive
panting; weight gain; a pot-bellied appearance; hair loss; haircoat
changes; and lethargy. These symptoms are a direct result of the
excess cortisone in the blood. Cushing's Disease typically affects
middle-aged to older dogs. Poodles, dachshunds, Boston terriers
and boxers are predisposed to developing Cushing's. However, any
breed can be affected. The first step in diagnosing Cushing's Disease
is through general bloodwork, which will indicate Cushing's as a
possibility. Definitive diagnosis requires special testing where
the cortisohel levels in the blood are measured.
What if my dog has Cushing's Disease?
There are several treatment options available. The most common
treatment is with a drug called Lysodren (mitotane). Lysodren causes
the destruction of the adrenal gland layers producing the excess
cortisone. It lowers the amount of cortisone in the blood, reducing
the symptoms and adverse effects the cortisone has on the body.
Unfortunately, there can be serious side-effects with therapy.
The biggest concern is that the Lysodren will destroy too much
of the adrenal gland, causing a potentially fatal condition where
the adrenal glands can no longer produce the cortisones that are
essential for life. This condition, hypoadrenocorticism, would require
lifelong medication to supply the body with what it no longer can
produce.
While it is estimated that this happens to approximately 5 percent
of dogs treated with Lysodren, close daily monitoring can reduce
the chances that a dog will develop this particular side-effect.
Other side-effects include vomiting, diarrhea and weakness. Consistent
monitoring and rechecks are required for any dog on Lysodren therapy.
A newer option for medical treatment of Cushing's Disease is a
drug called Anipryl (selegiline). This treatment is only effective
in cases where Cushing's Disease is caused by a tumor in the pituitary
gland (Anipryl will not work in cases of adrenal tumor).
Anipryl works by interfering with the tumor's production of stimulating
hormone. With less stimulating hormone, the adrenal glands produce
less cortisone. One advantage of Anipryl is the lesser occurrence
of side-effects. Also, there is no risk of Anipryl causing hypoadrenocorticism.
Note that not all dogs will respond to treatment with Anipryl, and
it may take one to two months for improvement to show.
For dogs that have adrenal tumors causing Cushing's Disease. surgery
may be an option. An adrenalectomy (removal of the adrenal gland
with the tumor) can be done, although this is generally a procedure
done only at a surgical specialty hospital or veterinary school
hospital.
It is important to know that even if a dog is being successfully
treated, there can still be complications due to Cushing's Disease.
These complications include high blood pressure, congestive heart
failure, recurrence of the original symptoms, and thromboembolism
(blood clots that cause a lack of blood flow to the affected area,
and which can also cause a stroke). Due to these complications,
dogs with Cushing's Disease have an average lifespan of two years
following diagnosis.
|
