Addison’s disease occurs when one of the body’s hormone producing glands, called the adrenal glands, fail to produce adequate amounts of cortisol and, in most cases, aldosterone. These hormones are essential for maintaining normal metabolism, electrolyte balance, and the body’s ability to respond to stress. Addison’s is often dubbed “the great pretender” because its symptoms mimic many other conditions/disorders. Symptoms can include lethargy, loss of appetite, vomiting, diarrhea, weight loss, shaking, or collapse. These signs often wax and wane, making it more difficult to recognize and diagnose.
Dogs with Addison’s disease are most commonly young to middle-age dogs, female, and Standard Poodles, Portuguese Water Dogs, and West Highland White Terriers are over-represented. However, the author has diagnosed this condition in all ages, breeds and both sexes.
A classic laboratory finding of a dog in an Addisonian crisis is a low sodium and high potassium, which can lead to dangerous cardiac abnormalities. Bloodwork may also find elevated kidney values (azotemia), a low blood sugar (hypoglycemia), and a low cholesterol.
There is an even trickier version of Addison’s disease called Atypical Addison’s Disease, in which dogs stop producing only cortisol, an essential hormone for a dogs stress response. As a result, there may be no bloodwork abnormalities other than a lack of changes in white blood cells called a “stress leukogram”.
A screening test called a baseline cortisol is available. If this test is low, a definitive diagnosis is made with an ACTH stimulation test.
Once diagnosed, Addison’s disease is very manageable with lifelong hormone replacement. Dogs with typical Addison’s require both glucocorticoids (like prednisone) and mineralocorticoids (either DOCP injections or oral fludrocortisone), while dogs with atypical require only glucocorticoids.
During times of stress, dogs with Addisons disease should be given a “double” dose of their glucocorticoid. Stress can be either physical (such as an injury or illness) or psychological (such a veterinary visit for a dental/anesthetic event, a trip to the groomer (for some dogs), thunderstorms or fireworks (if the dog has phobias) or travel).
For pet owners, the prognosis is excellent with proper management. Regular veterinary follow-ups, bloodwork, and medication adjustments help maintain stability. With proper management, dogs with Addison’s can live long, healthy lives.
If your dog is showing vague signs of illness that come and go, ask your vet if Addison’s should be ruled out. For veterinarians, having Addison’s on your differential list can be lifesaving.