What is the adrenal gland?
The adrenal gland makes several types of hormones. If the adrenal gland produces too many of these hormones, it is a disease called Cushing’s disease. If the adrenal gland has a decreased production of these hormones, it is called Addison’s disease. President John F. Kennedy had Addison’s disease. There are two types of hormones produced by the adrenal gland. One is called mineralocorticoids, which regulate sodium and potassium values in blood. The other is called glucocorticoids, which regulates glucose metabolism in the body. In Addison’s disease, both hormones are decreased.
Addison’s disease usually develops when the adrenal glands are attacked by the immune system. The triggering event for this problem is unknown. Clinical signs include intermittent vomiting, decreased appetite, weight loss and sometimes diarrhea. Lethargy, depression and weakness are also common. In some animals, signs wax and wane; in others, an acute crisis develops with the animal showing signs of collapse, dehydration and shock.
A diagnosis of Addison’s disease always requires laboratory testing, because no clinical sign is specific for Addison’s disease. Classic findings on a chemistry profile of the blood include low sodium, high potassium, low chloride and sometimes high calcium levels. We can measure blood cortisol, and this is always low in Addison’s disease. Other tests that may be run, depending on the presenting clinical signs, include chest and abdominal X-rays, an electrocardiogram, a urinalysis, an abdominal ultrasound and a stool exam.
Animals in an acute crisis require hospitalization for intravenous fluids, injectable steroids and medications to lower blood potassium levels. Shock must be treated aggressively, as an acute crisis can be life-threatening and reversed only through intensive care. For most dogs with Addison’s disease, lifelong supplementation with mineralocorticoids is needed. This usually involves the administration of a drug called fludrocortisone on a daily basis. Oral glucocorticoids are also given for life.
If the animal survives an acute crisis, then the disease is often very manageable. Treatment of the disease can be rewarding, because most animals respond well to the medications. Because adrenal gland hormones help to combat stress, affected animals often do not handle physical stresses very well. During periods of stress, extra steroid supplementation may be needed, and close monitoring for signs of relapse is important.
Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.