Cushing's Disease (Hyperadrenocorticism)

            Cushing's disease is a common disease in older dogs which manifests itself in multiple clinical signs related to a high circulating cortisol level. The disease is rare in cats. Poodle, dachshund, Boston terrier, boxer, and beagle are the most represented breeds. 

            There are two important glands associated with the kidneys called the adrenal glands. These glands secrete steroidal hormones that effect many physiological processes. The adrenal glands are regulated by another central gland called the Hypophysis (pituitary gland) which is associated with the brain. Spontaneous Cushing's disease in 85-90 percent of dogs is caused by a tumor or hyperactivity of the Hypophysis. The remaining 10-15 percent suffer from adrenal gland tumors, of which 50% are malignant. Prolonged treatment with Prednisone or other Glucocorticosteroid medications can also cause Cushing's disease.

            Signs, which may vary among dogs, include, excessive drinking and urination, pot-belly abdomen, symmetrical or generalized hair loss and thin hair, comedomes (black heads), pigmentation and skin lesions caused by calcium deposits, weakness and under- developed muscles, lethargy, panting, facial nerve paralysis and sex organ atrophy. 

            Blood and urine tests are the main diagnostic tools, as well as imaging. Specific screening tests that increase the accuracy of the diagnosis are done as well.  

            Treatment is usually medical. In some cases of operable tumors, surgery is indicated. Medical treatment is life long and aims at reducing the adrenal gland secretions. Side effects are not uncommon and close veterinary monitoring is necessary. Left untreated, the disease progresses more rapidly and culminates in early death. 

            Any dog with increased drinking and urination should be seen by the veterinarian and tested for Cushing's disease. All senior pets (over seven years of age) should be checked by a veterinarian every six months and have periodic screening laboratory tests done.