Addison's Disease
(Hypoadrenocorticism)

The adrenal glands are situated in the body at the cranial edge of the kidneys. Adrenocortical insufficiency or hypoadrenocorticism results from deficient production of glucocorticoids, mineralcorticoids, or both.

Mineralcorticoids are responsible for the reabsorption of sodium and chloride. Decreased mineralcorticoid secretion results in loss of sodium, which causes an increase of potassium in the blood. High blood levels of potassium can lead to life threatening heart problems.

Glucocorticoids have a multitude of functions and effects. They are involved in carbohydrate breakdown, they enhance glycogen storage and they surpress systemic immunity. Decreased glucocorticoid secretion can gause gastrointestinal signs such as loss of appetite, vomiting and abdominal pain.

Most cases of Addison disease are thought to be immune mediated. It is a relatively uncommon disease in dogs and extremely rare in cats. There may be a genetic predisposition in several breeds of dogs, including standard poodles, Labrador retreivers, and Portugese water spaniels.

Signs of Addison's Disease

A high index of suspicion is often needed to diagnose this uncommon disease. The trouble with diagnosis is the signs animals have with Addison's are similar to the signs of numerous other conditions. There is no one clinical sign that pinpoints one to diagnose Addison disease. Common clinical findings are depression, weakness, gastrointestinal upset and a slow heart rate.

Diagnosis

The diagnosis of this disease relies on laboratory evaluation. Many dogs will have hyperkalemia (high blood potassium) and hyponatremia (low blood sodium). Definitive diagnosis requires more specific hormonal testing.

Treatment

Acute adrenal failure is a medical emergency. Initial therapy includes intravenous fluids and replacement steroids. Once the patient is stabilized, lifelong supplementation of mineralcorticoids and occasional glucocorticoids is needed. Periodic blood monitoring is required. Addisonian patients if properly treated and monitored can lead a full and happy life.