CUSHING’S SYNDROME (CUSHING’S DISEASE)
Anne Jones RN, BSNE
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Cushing’s is considered a disease of older dogs. However, we have
reports of Cushing’s occurring in Bichons as young as 6 years of
age. The presence of Cushing’s is not a normal sign of aging and can
be treated with some success. In Bichons, it appears often to be
associated with over or extended use of steroids being used to
suppress the symptoms of allergy. However this is NOT the only
reason for the presence of Cushing's disease in Bichons. The disease
may be inherited and is considered one of the principle endocrine
disorders in the breed. It often occurs concurrent with diabetes and
sometimes with pancreatitis.
Signs and symptoms of Cushing's are numerous and often mimic other
disorders, particularly aging. Your dog age 6 years old or older may
have any or all of the following: constant panting, lethargy,
strange behaviors, excessive thirst and frequent urination,
increased appetite with resulting obesity, enlarged abdomen (which
may be edema rather than weight gain), thinning of hair, thinning of
the skin, susceptibility to skin infections and slow healing,
seeking cool surfaces to lie on, erratic sleep habits and
restlessness, lethargy and depression, failure to respond to owner
in a normal pattern, diarrhea and/or vomiting, darkening of skin -
especially on the abdomen, muscle stiffness, muscle weakness -
especially of the rear legs, infertility, a skull-like appearance of
the head, and/or seizures. Since these signs may appear in other
conditions, blood workup by a veterinarian is definitely in order!
Do NOT wait for seizures to develop and be prepared to test for
diabetes at the same time. Insulin therapy is not always successful
in the presence of both Cushing's and diabetes.
Cushings's is known as hyperadrenocorticism and it occurs when too
much cortisone or glucocorticoid is present in the body. The hormone
cortisol maintains normal blood glucose levels and plays a part in
the metabolism of fat as well as the working of the vascular and
nervous systems. Overproduction affects these systems as well as
kidneys and the immune system.
Causes may include adrenal gland tumors, pituitary gland tumors or
constant use of steroids - in Bichons used to treat allergy. It is
important to determine which of the causes has made the dog sick. A
first step is to have your veterinarian examine the dog. He may test
for serum alkaline phosphatase, cholesterol, alanine transferase,
blood glucose, and urinalysis to check for low specific gravity and
high protein levels. CT scans, ultrasound or x-ray examination may
be needed. Old tests for Cushing's that used ACTH were extremely
expensive. Today a low dose dexamethasone test may be used. If the
dexamethasone does NOT suppress the level of cortisol in the blood,
Cushing's is suspected. A further test may be necessary to determine
if the disease is from adrenal gland tumors or pituitary tumors.
These tests are rather costly but necessary for diagnosis.
In the case of the dog on daily or frequent doses of steroid
treatment, the veterinarian may advise a gradual reduction and
finally elimination of the steroid to see if the symptoms abate.
This is a judgment that must be made under advice of the
veterinarian and the dog must be monitored throughout. Blood tests
and other lab work may still be needed to determine if the dog has
true Cushing's. The disease occurs often enough to suspect other
causes than steroid use. As mentioned earlier, the disease often
occurs with or is followed by the developing of diabetes mellitus.
In recent years, the same drug that is used to treat Cognitive
Dysfunction (senility) in dogs is one that is sometimes used to
treat Cushing's. The drug Anipryl (generic name selegiline) works to
suppress the pituitary gland and may be effective if the cause is
pituitary tumor. Earlier drugs used to treat Cushing's (Lysodren,
ketaconazole, Mitotane) all can have very serious side effects and
need close monitoring. These are all being used in severe cases of
Cushing's. Monitoring of food and water intake is necessary to know
if and when the drugs are effective (usually within 2 weeks). It is
noteworthy that Addison's disease (hypoadrenocorticism) is rarely
seen in Bichons. However it can result when treatment by Lysodren is
overdone. Addison's is an inherited condition in some breeds.
Many veterinarians use a two year estimate for life span following a
diagnosis of Cushing’s so you can see need to both treat and to
monitor treatment. With the numbers of cases of Cushing’s that are
seen in Bichons, this further strengthens the need for breeders to
eliminate serious allergies in the breed and to avoid the use of
steroids in treating those with allergies. If steroids must be used,
try to use a single dose and then switch to antihistamines or to
give the prednisone on alternate days rather than daily.
Material obtained from Merck Manual, Your Dog magazine and
various medical and veterinary texts.
Dogs, Diet, and Disease: An Owner's Guide to Diabetes Mellitus,
Pancreatitis, Cushing's Disease, and More by Caroline D. Levin RN
http://www.petcarebooks.com/books/ddad.htm
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