Cushing’s Disease ( Hyperadrenocorticism)
Cushing’s syndrome happens when your dog’s body makes too much of a hormone called cortisol. This hormone helps him respond to stress, control his weight, fight infections, and stabilize his blood sugar levels. But too much or too little cortisol can cause problems.
Cortisol is produced by the adrenal glands, located next to the kidneys. The adrenal glands are stimulated by the pituitary gland (located at the base of the brain) to produce cortisol. Cushing’s disease may be due to overproduction in the adrenal glands or overstimulation of the adrenal glands by the pituitary gland.
WHAT CAUSES THE DISEASE?
The most common cause of Cushing’s disease (85% to 90% of all cases) is a tumor of the pituitary gland. The tumor may be either benign or malignant. The tumor causes the pituitary gland to overproduce a hormone (ACTH) that stimulates the adrenal glands to produce cortisol. The tumor may be microscopic or large.
Cushing’s disease may also be the result of a benign or malignant tumor of the adrenal gland. If the tumor is benign, surgical removal will cure the disease. If the tumor is malignant, surgery may help for some time, but the prognosis is much less favorable.
WHAT ARE THE SYMPTOMS?
Cushing’s disease can be tricky for a veterinarian to diagnose, because it has the same symptoms as other conditions.
Common symptoms include increased thirst and urination, insatiable appetite, enlarged or saggy abdomen, hair loss, lethargy or weakness, panting, and recurrent infections.
Cushing’s disease is most prevalent in the Poodle, Dachshund, German Shepherd and terriers, such as Yorkies. The Boxer, Boston Terrier, Labrador Retriever, Australian Shepherd, Maltese, and Cocker Spaniel may also be at increased risk.
HOW DO YOU DIAGNOSE CUSHING’S DISEASE?
Cushing’s disease can be difficult to diagnose. Tests that may be needed to diagnose Cushing’s disease include;
-Complete blood count (CBC), chemistry panel and urinalysis with culture: These tests evaluate the overall health of your pet and help determine if other health problems are suspected.
– Urine cortisol : creatinine ratio test: This is a urine test that is used as a screening test to determine if the more expensive blood tests should be run to diagnose Cushing’s disease.
– Low-dose dexamethasone suppression test: This test looks at how your dog’s body works with an injectable version of the steroid cortisol. This test is performed over an 8 hour period. A blood sample is drawn, a steroid injection is given, and then additional blood samples are taken after 4 hours and 8 hours. This test is used to diagnose Cushing’s disease in a pet. Sometimes this test can determine whether the issue is from the pituitary gland or adrenal glands. Occasionally this test will need to be repeated in 2 – 3 months if the results fall into a “gray zone” and it is unclear if the diagnosis is Cushing’s disease has been confirmed.
– ACTH stimulation test (Adrenocortcotrophic hormone): It measures how well the adrenal glands work in response to a hormone. This test involves obtaining a blood sample, administering a hormone injection, waiting an hour, and then obtaining another blood sample. This lab test is used to diagnose Cushing’s disease and to evaluate the effectiveness of therapy.
– Radiographs or abdominal ultrasound: Radiographs can help your veterinarian see changes in organs that could indicate Cushing’s disease. An abdominal ultrasound can help your veterinarian visualize the adrenal glands and evaluate their size and shape.
WHAT ARE MY PETS TREAMENT OPTIONS?
If an adrenal tumor is identified, surgical removal may be an option. However, non-surgical treatment is most often used. There are currently several different medications being used to treat Cushing’s disease.
Trilostane is the most common treatment that is used to treat dogs with Cushing’s disease. It is a good alternative treatment for dogs with adrenal tumors. During the initial phase of treatment the dog is examined often and ACTH stimulation tests are performed. Trilostane decreases the production of cortisol in the body.
Lysodren was the only treatment available for Cushing’s disease for many years. It is convenient to use and relatively inexpensive. However the downsides of this drug are the serious side- effects. Regular blood monitoring needs to be performed. During the beginning of therapy, your dog must be carefully monitored. The use of Lysodren is similar to chemotherapy. It works by destroying cells of the adrenal gland that produce corticosteroid hormones.
WHAT IS THE PROGNOSIS OF CUSHING’S DISEASE?
If the activity of the adrenal gland can be controlled, many dogs with Cushing’s disease can live normal lives for many years as long as they take their medication and stay under close medical supervision. If the Cushing’s disease is caused by a pituitary tumor that begins to grow in size, it will affect the brain, often resulting in neurological signs and giving the pet a less favorable prognosis.
As always, please talk with your veterinarian about your pet’s diagnosis and prognosis with any health concerns.