Cushing’s disease (also called hyperadrenocorticism) is a condition caused by the production of excess amounts of the hormone cortisol. Cortisol is made by the adrenal glands of the body and then released into the bloodstream. It has many important functions such as combating stress, ameliorating inflammation, and helping to make available energy stores to the body by encouraging the break down of muscle and fat. It is a critical hormone for many normal body functions.
What causes Cushing’s disease?
The answer to this question is a bit complex in that there are several possible causes and multiple tests are often needed to pinpoint the exact cause in any given individual. In most dogs (about 80 to 85% of cases), the disease occurs due to a benign secretory tumor of the pituitary gland. In other dogs (about 15% of cases), the disease occurs due to a tumor in one of the adrenal glands (in some cases, these tumors are benign and in some cases they are not).
What are common clinical signs?
While normal amounts of cortisol are protective to the body, excessive amounts can become quite detrimental as the disease progresses. Each patient is a bit different in the symptoms that they show, but some common clinical signs include increased appetite, increased thirst, increased urination, panting, the breakdown of body muscle (loss of abdominal muscle may result in a “pot belly” appearance in some dogs), enlargement of the liver, hair loss, and increased incidence of infection (especially in the skin and urinary tract). Other clinical signs (hypertension, proteinuria) may also occur but are less common. Lastly, in some dogs with the pituitary form of the disease, signs of brain disease may occur (unexplained changes in behavior, abnormal gait), as the tumor enlarges enough to compress nearby structures.