Canine Test for Cushing's Disease

Canine Cushing's disease is an endocrine problem in which the adrenal glands produce too much of a specific component called cortisol. This imbalance in hormone produces visible symptoms in the animal and can shorten its life. Cushing's disease generally affects older animals, usually over the age of 8 years. Veterinary treatments for canine Cushing's disease can extend your dog's life and increase the quality.

  1. About Cushing's Disease

    • Cushing's disease, also known as hyperadrenocorticism, occurs when the adrenal glands that are located near the kidneys begin to overproduce a hormone called cortisol. Because cortisol affects the function of so many organs in the body, the symptoms can vary widely. Many animals develop a pot-bellied appearance, increased thirst and urination, increased appetite and skin problems. Some experience hair loss, panting, weakness and blood clots. The large amount of cortisol in the bloodstream suppress the immune reaction and the animal may be prone to bacterial infections, such as urinary infections. Several medications are given to inhibit cortisol production. In some cases, surgery is indicated.

    Diagnosing Cushing's Disease

    • No single test will diagnose canine Cushing's disease. A combination of medical history, physical examination, laboratory tests and X-ray or ultrasound will all point strongly to the likelihood of tumors on the adrenal glands that cause Cushing's disease. Cushing's disease can either be adrenal-dependent or pituitary-dependent. These tests will indicate which kind of Cushing's disease is involved.

    Urine/Creatinine Ratio Test

    • This test measures the amount of cortisol in the urine to use as an indication of how much is in the bloodstream. The creatinine is also measured to determine the amount of urine dilution that is present. It is an easy test that only requires a morning urine sample. This test, however, may be indicate high levels even when Cushing's disease is not the underlying problem, so other tests must be done to confirm the result.

    Low Dose Dexamethasone Test

    • In this test, an injection of dexamethasone, a form of cortisol, is given to the animal and blood tests are taken after four hours and again after eight hours. These are compared with pre-injection blood tests. If the four-hour or eight-hour test is greater than 50 percent of pre-injection level, Cushing's disease is indicated.

    High Dose Dexamethasone Test

    • This is a test given to discover whether the Cushing's disease is adrenal or pituitary in origin. It is administered like the low dose dexamethasome test, but with a higher dose. If the tumor is adrenal, levels will be elevated.

    ACTH Stimulation Test

    • In this test the dog is given an injection of ACTH, which stimulate the adrenal glands to produce cortisol. Then it is compared with a resting blood sample that is taken before the injection. If the post-injection level is much higher than the resting level, Cushing's disease is indicated as the cause 80 to 90 percent of the time. The test does not indicate whether the Cushing's disease is adrenal or pituitary in origin.