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Adrenal Insufficiency

Issue Description
There are three forms of Addison's disease: primary, secondary and atypical. Primary and atypical Addison's are usually the result of immune mediated damage to the glands. Secondary hypoadrenocorticism is from failure of the pituitary to stimulate the adrenals with adrenocorticotropic hormone (ACTH). It is important for you to know which type of Addison's disease your dog is being treated for.
Other Names
Addison's Disease, Hypocortisolism




Causes
Causes of adrenal insufficiency can be grouped by the way in which they cause the adrenals to produce insufficient cortisol. These are adrenal dysgenesis (the gland has not formed adequately during development), impaired steroidogenesis (the gland is present but is biochemically unable to produce cortisol) or adrenal destruction (disease processes leading to the gland being damaged).

Symptoms
Symptoms of Addison's disease are very similar to other diseases and they seem rather vague. Symptoms may include but are not limited too; middle age female dogs, usually over 7 years of age, depression, lethargy, weakness, not eating, weight loss, vomiting and diarrhea, drinking more, urinating more, dehydration, and a fast heart rate in some patients. Many times these symptoms may go unnoticed or correctly diagnosed and the patient finally presents in a Addisonian crisis. During an Addisonian crisis the patient may present in acute collapse and in shock. This is very serious, deadly, and scary to watch. Blood work will show low sodium level, high potassium level, and high kidney enzymes. Many veterinarians will first think kidney failure, which is more common then Addison's, and will recommend IV fluids. The IV fluids will correct the electrolyte imbalance and the dog will start to feel a lot better. The veterinarian may then start to think the patient could have Addison's instead of kidney disease and recommend other tests.

Diagnosis
The only definitive test for Addison's disease is the ACTH stimulation test. The patient receives a dose of ACTH, the pituitary hormone responsible for the release of corticosteroids in times of stress. A normal animal will show an elevation in cortisol in response to ACTH while an Addisonian has no corticosteroids to respond with. This lack of response is diagnostic for Addison's disease; however, a false positive may be obtained if corticosteroids have been used in the treatment of the crisis prior to the test. Only dexamethasone does not interfere with the assay for cortisol; if any other steroid has been used, the test will not be valid for at least a couple of days.

Treatment
Treatment for this disease is usually done by oral administration of fludrocortisone acetate (Flurinaf), salting the food, and administration of corticosteroids like prednisone. In a crisis situation this disorder must be treated more aggressively with intravenous fluids, IV glucocorticoids and correction of acid/base balances.