The adrenal glands are two very important glands that are located next to the kidneys. Everyone has them and they perform a variety of functions critical to maintaining a healthy life. Most importantly these glands produce a steroid hormone called cortisol. Proper levels of steroids are necessary for responding to stresses, regulating blood sugar, controlling the immune system, regulating electrolyte balance and helping with metabolism. Steroid hormones are responsible for the same critical functions in your dog.
Some dogs develop a disease called Cushing’s or hyperadrenocorticism that occurs when the adrenal glands produce too much steroid hormone. There are three separate ways in which an animal can develop Cushing’s disease. Pituitary gland tumors are the most common cause of Cushing’s. The mass in the pituitary gland causes it to produce excess levels of a hormone that then signals the adrenal glands to produce excess amounts of cortisol. A mass in the adrenal gland can also cause Cushing’s. Surgical removal of benign masses can cure the disease while surgical removal of cancerous masses usually only increases marginally extends the dog’s lifespan. The final cause of Cushing’s disease occurs when an animal receives excess amounts of a steroid. This is known as Iatrogenic Cushing’s.
Symptoms of Cushing’s disease can include an increase in appetite, drinking and urinating as well as lethargy, poor or dull hair coat, panting and a pot-bellied look.
Diagnosing Cushing’s disease is usually done with blood work. An ACTH-Stimulation test involves dropping your pet off at the veterinary clinic for several hours and determining baseline cortisol levels as well as levels after an injection of ACTH which is supposed to stimulate cortisol production. Other blood tests such as low-dose Dexamethasone suppression tests and urine cortisol tests are also helpful. Ultrasounds are also used to visualize the adrenal glands and look for potential tumors. Complete blood work should also be done on any dog that is being tested for Cushing’s disease.
Cushing’s disease is typically treated using a drug called Trilostane, which blocks excess production of cortisol in the adrenal gland or a drug called Lysodren. Trilostane is a very effective medication but can cause adverse side effects and is quite costly. When using Trilostane it is important that your pet is seen every 3-6 months for a veterinary check-up, ACTH-Stimulation test and complete blood work.