What is Addison's Disease?

What is Addison’s Disease?

               We’ve all heard of steroids, right? Prednisone is commonly used in both human and veterinary medicine. Our bodies also make steroids like cortisol. Steroid medications like prednisone and dexamethasone can cause increased thirst, increased appetite and other side effects. But our bodies need to produce some steroids in order to function properly. Addison’s disease (also known as hypoadrenocorticism) is a condition in which the patient’s adrenal glands do not produce enough of the hormones known as corticosteroids.  These include hormones like cortisol and aldosterone, important for the body’s response to stress and for keeping electrolytes such as sodium and potassium in balance. Without enough cortisol and other hormones, serious life-threatening illness can result.

               The cause of adrenal gland failure is often not known. Certain breeds such as Great Danes, Standard Poodles and Bearded Collies have a higher incidence of Addison’s disease, but any breed of dog can be affected. Females are affected twice as often as males and most dogs are young to middle-aged adults (about 3-5 years of age). Cats can get Addison’s disease but are rarely affected.

               Symptoms are often vague and may come and go—dogs may present with lethargy, vomiting, diarrhea, loss of appetite.  If undiagnosed, dogs can experience what is known as an Addisonian crisis—they become seriously ill and go into shock—the dog may collapse, her blood sugar may drop dangerously low, and she may have a very slow heart rate or even an arrhythmia. Addisonian crisis is an emergency and can be fatal if not treated. Dogs in crisis need IV fluid support and other treatments to treat shock as well as IV dexamethasone (a synthetic steroid).

               Patients not in crisis but suspected of having Addison’s disease need blood tests to diagnose the disorder. An electrolyte panel may show electrolyte disturbances such as high potassium and low sodium levels and many patients also have elevated kidney values and low blood sugar. However, not pets have these classic electrolyte changes so a specific test called an ACTH stimulation test is needed to definitively diagnose the disease. This tests the ability of the adrenal gland to produce cortisol in response to a drug called cortrosyn.  If the adrenal gland fails to produce enough cortisol after being stimulated by the drug, the dog has Addison’s disease.

               Addison’s disease is a treatable disease but does require lifelong medication.  It cannot be cured. Dogs are usually treated with either an injectable drug called DOCP (Percoren, Zycortal) given as an injection under the skin once every 3-4 weeks or with a daily oral drug like fludricortisone to replace lost mineralocorticoids plus dogs need a daily low dose of prednisone. Dogs may need increased prednisone during stressful events such as when traveling or boarding, when having surgery, etc.

Some dogs have atypical Addison’s disease—they still have mineralocorticoid production but insufficient cortisol thus they only need prednisone supplementation. Occasionally, Addison’s disease is induced by drugs like trilostane or by suddenly stopping long term, high doses of steroids.  Drug induced Addison’s disease does not usually require long term treatment—stopping or adjusting the drug that caused the decreased cortisol production will usually allow the adrenal gland to return to normal function.

               If your dog has vague waxing and waning symptoms of feeling ill your vet will likely want to check your pet for Addison’s disease and it will likely be on the list if your dog suddenly collapses or goes into shock after the pet is stabilized. Addison’s requires lifelong treatment but dogs can do very well once regulated.

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               This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communites.