Addison's Disease in Dogs: An Overview

Dog Breeds

Addison’s disease, which is technically called hypoadrenocorticism, is defined as diminished hormone production from the cortex of the adrenal glands. The adrenal glands are paired endocrine organs located next to the kidneys that produce and regulate a number of steroid hormones.

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Definition of Addison’s Disease

Addison’s disease, which is technically called hypoadrenocorticism, is defined as diminished hormone production from the cortex of the adrenal glands. The adrenal glands are paired endocrine organs located next to the kidneys that produce and regulate a number of steroid hormones. The adrenal cortex can be damaged by trauma, hemorrhage, mineralization, cancer, immune-mediated destruction, infection and a number of other things. It is generally thought that approximately 90% of the adrenal cortices must be destroyed before dogs will show observable signs of Addison's disease. Addison’s can be life-threatening. It cannot be cured but, if caught early, it usually can be controlled.

Causes of Addison’s Disease

The cause of Addison’s disease is not always able to be determined but is thought to be the result of atrophy of all layers of the adrenal glands. It can be caused by defects in the dog’s immune system which basically cause the body to attack itself. Other causes may include overdoses of certain medications, metastatic tumors/cancer and granulomatous disease. Addison’s can also be caused by injury to or disease of the pituitary gland and, more commonly in dogs, by long-term oral or injectable corticosteroid administration. Ultimately, anything that adversely affects the adrenal glands’ ability to produce the normal quality and quantity of adrenal hormones can be a contributing cause of Addison’s disease.

Preventing Addison’s Disease

There is no way to prevent Addison’s disease in dogs. The recommended approach for affected animals is to start glucocorticoid hormone replacement therapy for the lifetime of the dog, and possibly to increase the dosage of replacement hormones during periods of particular stress. Reliable tests are available to diagnose this disease, and there are good protocols for managing the condition by orally supplementing the dog with the hormones that its adrenal gland is not producing.

Special Notes

If left untreated, or if diagnosis is delayed, Addison’s can be fatal. Lack of sufficient adrenal hormones leads to elevated potassium levels and low sodium and chloride levels, which cause severe dehydration, depletion of circulating blood volume and problems with the heart and other organs. This is called an “Addisonian crisis” and must be treated aggressively. The prognosis for dogs with Addison’s is usually very good if the condition is detected early in its course. Unfortunately, diagnosis can be difficult because the clinical signs of Addison’s are nonspecific and can mimic those of many more common ailments.

Symptoms and Types