Introduction
Cushing's Disease is an umbrella term that refers to a number of conditions that occur when an animal is exposed to too much steroid hormone (called glucocorticoids). Cushing's disease occurs when the body produces excessive amounts of steroids, usually as a result of a pituitary gland problem, adrenal gland tumor, or too much steroid medication. The most common cause of Cushing’s Disease is a tumor of the pituitary gland in the brain.
Cushing's disease is extremely rare in cats, but occurs with some regularity in dogs, especially middle-aged ones and that weigh less than 45 lbs.
Symptoms of Cushing's Disease in Cats
Cushing's Disease progresses very slowly and initially very few owners notice that there is anything wrong with their pet. In some cases, it can take anywhere from six months to six years before a diagnosis is made. This is primarily because changes occur so gradually, that many owners think the changes are the result of normal aging.
The first and most common sign of Cushing's disease is often excessive thirst and excessive urination. The pet may ask to be let out at night to urinate or may have accidents in the house. It may also have an increased appetite that leads to stealing food, eating garbage, and continuous begging at the table. This increased appetite may lead owners to believe that there is nothing really wrong with their pet.
Other classical symptoms of Cushing's disease include abdominal enlargement (pot-bellied appearance), lethargy, panting, muscle weakness, and frequent skin infections. Hair loss often occurs from the trunk of the body but not from the head or the legs. Diagnosis of this disease is usually via blood tests.
Treating Cushing's Disease
Treatment of Cushing's disease centers on decreasing or stopping the excessive production of steroids by the body. If the cause is a tumor, this could involve surgical excision of the tumor or of the adrenal gland. If this is not possible, drugs can be used, including mitotane ketoconazole, and more recently, 1-selegiline (Anipryl™). Anipryl™ (l-selegiline) is a drug that was introduced for the treatment of Cushing's disease. Unlike mitotane, which destroys parts of the adrenal gland to keep it from producing too much steroid, 1-selegiline promotes normalization of the metabolism of a substance called dopamine. This results in a normal amount of steroid production and an amelioration of clinical signs.