Hypoadrenocorticism (Addison's)

Disease This condition occurs when the adrenal glands, two small glands that are near the kidneys, don't secrete enough hormones. The most important hormones are mineralocorticoids and glucocorticoids (cortisol). These hormones are responsible for many of the body's functions including the ability to use glucose, dealing with stressful events and the maintenance of normal levels of electrolytes such as sodium and potassium. Addison's occurs when there are insufficient levels of both hormones or of just glucocorticoids. Demographics The condition is most common in young, female dogs but can manifest later in life and in male dogs. Cats are rarely affected. Signs Signs associated with insufficient production of these hormones vary. It can be chronic and vague (known as "waxing and waning" signs- good days and bad days) with recurrent periods of poor appetite, vomiting, diarrhea and weakness or it can present acutely with sudden collapse and shock. Its presentation can mimic many other diseases including kidney, neurological and gastrointestinal disease, and tests are needed to differentiate Addison's from other conditions. Diagnosis Routine blood tests can suggest this disease, especially when there are low blood sugar levels, high calcium levels, low sodium levels, high potassium levels and low red blood cell counts. But patients with Addison's may not have all of these changes. The most definitive test to determine if a pet has Addison's or not is to do an ACTH stimulation test. This test will indicate if the animal has normally functioning adrenal glands or not. Two blood samples are obtained to measure cortisol levels in response to the administration of a hormone (adrenocorticotropic hormone). In normal dogs, there will be an increase in blood cortisol levels between the first and second samples. In dogs with Addison's, the cortisol levels start low and stay low since they can't respond appropriately. Treatment The main goal of therapy is to replace the hormones that pets with Addison's can't make. This can be done with an oral medication called fludrocortisone (Florinef) that must be given daily. It is mostly a mineralocorticoid, but it also has some glucocorticoid activity. There is also an injectable medication called desoxycortisone pivalate (DOCP) that can be given about every 25 days, according to the pet's needs. Since this is only a mineralocorticoid, a small amount of an oral supplementation of glucocorticoids in the form of prednisone or prednisolone must be given daily or every other day. Every dog varies in its response to medication and thus must be closely monitored, especially in the initial phases until it can be determined how that individual is responding. It is important that the pet owner of a dog with Addison's is aware that stress of travel, grooming, boarding, surgery or other activities may necessitate a temporary increase in the amount of glucocorticoids that help the body cope with stress. Monitoring It is important to evaluate the pet clinically (i.e. energy levels, resolution of signs of vomiting, etc) as well as with laboratory tests such as electrolyte levels and kidney function. At first, after the initiation of treatment, it may be necessary to frequently check these levels. Once the pet is stabilized and its needs for the medications are determined, checking the pet every 4-6 months is usually sufficient. Prognosis At all times, the owner must stay vigilant for a decline in the pet's condition and recurrence of the previously noted signs. With the appropriate medication and close monitoring from the owner and veterinarian, pets with Addison's can live a normal, good quality of life. However, the pet owner must be prepared for expenses associated with the medications (Florinef and DOCP are both expensive) and with rechecking laboratory tests. If there are any problems or questions, please contact your veterinarian. The above is general veterinary information. Do not begin any course of treatment without consulting your regular veterinarian. All animals should be examined at least once every 12 months.