A recent case involves my patient, Julie, a sweet, mellow Scottish Terrier who came in with a variety of different symptoms, some vague and some quite specific. Following a battery of tests; we finally came to this conclusion: Canine Hyperadrenocorticism, a big word for Cushing’s disease. Essentially, it is caused by having too much of a glucocorticoid called Cortisol, which can cause abnormalities in several different organ systems. This disease will affect the skin, muscles, hormones, urinary system, central nervous system and even the reproductive organs in non-neutered animals. Because so many organ systems are influenced by the excess glucocorticoid, symptoms are many and varied. Cushing’s disease occurs more often in German Shepherds, Poodles, Boxers, Boston Terriers and Dachsunds, but any breed can be affected. The age predilection is middle-aged to older dogs, but again, diseases don’t like to follow the textbook outside of veterinary school, so we can see any senior dog with Cushing’s disease.
One good thing about Cushing’s syndrome is that the symptoms that are often displayed do follow the textbook. Ask any vet student to rattle off symptoms of Cushing’s and every one of them will say: pot-bellied appearance, thin skin, muscle atrophy, bilaterally symmetrical hair loss, drinking and urinating more and hyperpigmentation. A few will even throw in calcium deposits and a ravenous appetite. These dogs will often pant for a number of reasons, including an enlarged liver pushing on abdominal contents, the pot belly and the effects of excess cortisol. Other complications, such as diabetes, can arise as increased cortisol in the blood takes its toll on other organ systems. There are three causes of Cushing’s: iatrogenic, meaning people caused the problem by giving the dog too many corticosteroids; pituitary dependent; and adrenal gland tumors that secrete cotiosol. About 80 percent of these cases are caused by pituitary tumors. Pituitary tumors tell the adrenal glands to ramp up cortisol production, and the adrenal gland obeys, to the dismay of the pet and his owners. Fifteen percent of Cushing’s cases are caused by tumors of the adrenal gland. The trick is to diagnose the disease correctly and then differentiate which type of Cushing’s it is; pituitary, adrenal or human induced.
Diagnosing Cushing’s is not complicated, but it involves a four-step process. And you really don’t get a final answer until the final tests are done. Even then, you may have to do further testing to come to a complete conclusion.
By this time, owners are frustrated and want to know the ultimate answer after every test. I advise all my clients ahead of time that at the conclusion of the first three steps, we still won’t have the real answer. Owners will ask, Why can’t we just treat it? We can’t treat it because the treatment for pituitary Cushing’s is different than the treatment for adrenal Cushing’s, which is different than the treatment for iatrogenic Cushing’s. Patience is called for here, as the frustrating nature of the testing procedure provides hints, but not a diagnosis until the end. And I really hate to say this, but some tests may need to be repeated or diagnostics performed. Your veterinarian will guide you through the treatment process, which may just involve medication but also could involve surgery and even radiation therapy.
Julie’s mom and dad were the most patient owners of a dog with Cushing’s disease I have ever encountered. Julie has the pituitary dependent kind and is beginning therapy to medically manage her condition. Wish her luck that all goes well, and that she loses her pot belly, and stops eating her mom and dad out of house and home. And I’ll do my best, Julie. LN