Hyperadrenocorticism, also referred to as Cushing’s Disease, is a common condition in older dogs. The disease is often mistaken for the normal aging process. Dogs affected with the disease will gain weight, lose hair, and urinate inappropriately in the house. All of which, unfortunately, prompt their owners to consider premature euthanasia.
In the normal, healthy dog, there is communication between two parts of the brain and the adrenal glands. This communication controls the output of cortisol in the body and ensuring that there is not excessive cortisol hormone in the circulatory system. Cortisol helps the body respond to stress. It is necessary for life and impacts a wide variety of bodily functions including blood sugar levels, fat metabolism, kidney function, nervous system, cardiovascular system, and immune response. The body produces high levels of cortisol when it is stressed due to pain, trauma, cold temperatures and for many other reasons. When the body is stressed, the communication system needs to slow down the production and release of cortisol from the adrenal glands.
In Cushing’s Disease, the communication loop has been disrupted for one of three reasons: a benign tumor in part of the brain, or an adrenal tumor, or because of drug side effects. The result of any of the three is a chronic excess of cortisol in the blood stream.
The most common cause of the Cushing’s is a benign pituitary tumor which tells the adrenal gland to produce too much cortisol. The tumor will not stop producing the hormone even when there is an unnecessary amount in the blood stream. Secondly, approximately 15 percent of dogs with Cushing’s will have a tumor on the adrenal gland which produces unwarranted amounts of the cortisol hormone. 50% of these tumors are benign and 50% are malignant. The third cause of Cushing’s Disease is from administering too much steroids to the dog.
Symptoms of Cushing’s disease can be vague and varied and tend to appear gradually and progressively. It is thus easy to mistake Cushing’s disease for normal aging. Additionally, many of the clinical symptoms are not unique to Cushing’s and could reflect a number of other health concerns. The most common clinical signs include increased water consumption, excessive urination to the point of incontinence, and an increased appetite. Many dogs will develop a saggy abdomen or a pot-bellied appearance with hair loss on either side of the abdomen. They may lose muscle in their face, down their back and over their hips. They commonly become lazier, and refuse to jump up anymore. They can pant excessively and become susceptible to skin diseases.
Cushing’s Disease may be suspected with the above mentioned clinical signs and a physical exam. Routine blood work will help rule out other diseases with similar appearances. The blood work may also be suggestive of Cushing’s. To confirm the diagnosis there are a variety of tests that may need to be performed. At Twin Valley VHS we perform the Low-Dose-Dexamethasone-Suppression test. This test helps us to evaluate the body’s response to the administration of excessive steroids or cortisol. Essentially, we are looking to see if the brain and the adrenal glands are communicating normally. Other tests may be required due to the complexity of the disease.
Treatment of Cushing’s Disease depends on the overall health of the patient. As many dogs with Cushing’s are elderly and may have concurrent health problems, treatment can be complicated. The comfort of the patient should be the ultimate goal. Cushing’s can be treated with surgery, radiation, or with drugs. At Twin Valley VHS, we recommend that the treatment options be discussed on an individual patient scenario.
If left untreated, Cushing’s Disease will progress. The progression may predispose the pet to hypothyroidism, pancreatitis, skin and urinary tract infections and diabetes. Heart failure and blood clots may develop later. The short term prognosis with treatment is very good. Symptoms should resolve in a few months. Dogs generally are more comfortable after the disease is under control and may live happily for years. There are some side effects with the treatment courses. This can be minimized with thorough communication between the owner and the veterinary staff. Cushing’s Disease is not something from which a dog recovers. Cushing’s disease is managed, not cured.
If you have any questions regarding the above information or any questions/concerns in general, please contact Twin Valley VHS at 745-6642.
Dr. Justin Noble DVM
Twin Valley Veterinary Health Services