Addison's disease is also known as hypoadrenocorticism. It results from the reduction in corticosteroid secretion from the adrenal gland. The adrenal gland is a small gland located near the kidney that secretes several different substances, including glucocorticoids and mineralocorticoids, that help regulate normal body functions. When the adrenal glands do not function properly, these hormones are not produced at sufficient levels to support metabolism and electrolyte balance.
What Are Glucocorticoids and Mineralocorticoids?
Glucocorticoids, such as cortisol, have an effect on sugar, fat, and protein metabolism. They are partially responsible for the reaction of the sympathetic nervous system known as the "fight or flight” response during stressful periods.
Mineralocorticoids, such as aldosterone, have an influence on the electrolyte levels in the body. They help regulate electrolytes, like sodium and potassium, particularly in stressful situations. When the adrenal glands do not function adequately, these hormones are not produced at sufficient levels causing the metabolism and electrolyte balance to be off creating the symptoms and complications of Addison's disease.
What Are The Symptoms of Addison’s Disease?
The symptoms of Addison's disease can be vague or they can be extreme in that they cause an immediate emergency crisis in response to a stressor. Many animals may have symptoms on and off for a long time before the disease is diagnosed. Some of the more common symptoms include lethargy, anorexia, vomiting, and muscle weakness. The symptoms may wax and wane, further complicating the diagnosis.
On the flip side, a pet may have what is called an 'Addisonian crisis’ in which they collapse in a state of shock due to an imbalance of electrolytes and metabolism during a period of stress. An Addisonian crisis needs to be treated immediately as a medical emergency.
How Is Addison’s Disease Diagnosed?
An animal that presents with a history of weight loss, lethargy, or muscle weakness, which are the symptoms of many diseases, will first get a chemistry profile and blood count to look at a number of body systems at once. Dogs with Addison's disease often have elevated blood urea nitrogen and an elevated creatinine, as well as decreased blood glucose. The blood count may show a chronic anemia. If the blood work supports the diagnosis of Addison's disease, then an ACTH stimulation test is performed.
Addison's disease in dogs is confirmed by a blood test called the ACTH stimulation test. In an ACTH test, the dog is given an injection of the adrenal-stimulating hormone ACTH. A normal dog will respond by having an increase in blood cortisol. If this does not happen the diagnosis of Addison's disease is confirmed.
If the patient has an Addisonian crisis with electrolyte imbalances, and responds to therapy, then a presumptive diagnosis of Addison's disease is made and once the animal recovers, the diagnosis can be confirmed with an ACTH stimulation test.
Addison’s can be difficult to recognize initially, but once it is diagnosed, it can be successfully treated.
Posted Friday, October 23, 2015