Cushing's disease (hyperadrenocorticism) may be the most frequent endocrine disease in adult to aged dogs but is infrequent in other domestic animals. The disease is insidious and slowly progressive.2 It results from an overabundance of adrenal hormone cortisol, a form of cortisone. Cortisol helps the body adapt in times of stress, regulate proper body weight, tissue structure, and skin condition Addison's disease (hypoadrenocorticism) is adrenal hormonal deficiency and is the opposite. Either will cause elimination problems. At risk for Cushing's disease are dogs that have been treated with corticosteroids. These drugs are often prescribed for animals with allergies and inflammatory conditions. This type of Cushing's disease is referred to as iatrogenic, meaning "doctor-caused." Several breeds have a hereditary tendency to develop hyperadrenocorticism including Boxer, various terrier breeds, Dachshund and Poodle. Almost all dogs diagnosed with hyperadrenocorticism are older than 6 years of age.
Increased thirst and urination are common signs of Cushing's disease. Increased hunger is another sign for many dogs with this illness. When muscular weakness develops, the dog will unavoidable break housetraining if it can't reach its potty area in time. Other signs of Cushing's disease are hair loss on both sides of the body, high blood pressure, thinning of the skin, fat deposits in the liver, calcium deposits in the skin and plugged hair follicles on the underside. Many dogs diagnosed with Cushing's disease also have a history of recurring urinary tract infections.
Diagnosis can be difficult with this disease, sometimes requiring analysis of numerous blood samples. In case of pituitary-dependent form of Cushing's disease, medications used for treating this disease inhibit steroid formation. Even when the cause of Cushing's disease is a tumor, most cases are not treated surgically. However, because of the complexity and risks of the surgery, most cases are treated with medications. Surgical techniques to remove pituitary tumors in dogs are being studied, but surgery is not a widely available option. 3 A dog diagnosed with Cushing's disease must remain on medication for the rest of its life and must frequently be re-tested to be certain it's still on the correct dosage as its body adapts to the medicine.
In December 2008, the Food and Drug Administration approved the first drug in more than 10 years to treat Cushing's disease in dogs. Vetoryl (trilostane) capsules, the latest drug approved to treat canine Cushing's, is also the first drug approved to treat both pituitary- and adrenal-dependent Cushing's in dogs. This prescription drug works by stopping the production of cortisol in the adrenal glands.3
- Stephen J. Ettinger, DVM, DACVIM and Edward C. Feldman, DVM, DACVIM. Textbook of Veterinary Internal Medicine
- Merck Vet Manuals. Hyperadrenocorticism
- Treating Cushing's Disease in Dogs