Addison’s Disease

Addison’s disease (hypoadrenocorticism) occurs when the adrenal glands fail to produce the hormones the body requires. (Much like when insulin is not produced resulting in diabetes.) Important adrenal gland hormones are steroids, namely aldosterone and cortisol. These hormones help regulate functions of different organs and body systems. Without them, the body deteriorates and can lead to serious complications and even death. The disease is not curable but is very treatable and if caught early Addisonian dogs can lead normal, active lives. Addison’s can develop in any dog, purebred or mixed breed. Portuguese Water Dogs are one of 7 or so purebred dogs that are predisposed to developing Addison’s. It has been seen in males and females and even puppies, though typically it is more common to present in young- to middle-aged dogs.


Addison’s has been known as the great imitator as it is hard to diagnose in early stages. Symptoms will wax and wane as the dog has recurrent bouts of gastroenteritis, poor appetite, loss of condition, and inappropriate response to stress. Some typical symptoms we see with progressing Addison’s are:
  • Poor appetite
  • Vomiting
  • Lethargy and Depression
  • Weakness/loss of body condition
  • Weight loss
  • Diarrhea
  • Shaking
  • Excessive thirst/excessive urination
  • Waxing and waning course of illness
  • Tender abdomen

If you think your dog has any of these symptoms, you should have him or her evaluated by your veterinarian promptly.

Addisonian Crisis

Many times, Addison’s presents in what is called an Addisonian Crisis, when the dog is further along in the disease course.  At this stage, the organs are debilitated and the dog is in a life-threatening shock and collapse state. Your veterinarian will perform tests to determine the cause of your dog’s symptoms, which will involve bloodwork, urinalysis, and evaluation of the heart with an ECG. Changes in the blood potassium/sodium levels can point towards Addison’s diagnosis.


The definitive test for Addison’s is the ACTH stimulation test. This test monitors the functional level of the adrenal glands – at rest and after chemical stress – by injecting with a synthetic version of a hormone, which is naturally produced by the pituitary gland, to stimulate the adrenal glands to release cortisol. In all cases of Addison’s disease, the results of this test will be abnormal because the adrenal glands are not working properly. In most cases of Addison’s, the sodium and potassium levels are also highly altered. When both the ACTH stimulation test and the sodium/potassium levels are abnormal, this is called typical Addison’s disease. There is a rarer form of the disease called atypical Addison’s disease in which only the ACTH stimulation test is abnormal, but the sodium/potassium levels are normal. Sometimes, atypical Addisonian cases can progress to typical Addisonian cases.


If your dog is diagnosed with Addison’s disease during an Addisonian crisis, your veterinarian may need to treat your dog with an emergent dose of steroids. Use of dexamethasone (dex) is preferred over prednisone as dex will not interfere with the results of the ACTH Stim test. Once the crisis is resolved, or if your dog is diagnosed during a regular office visit, your veterinarian will begin treating your dog with long-term medications. As with diabetes, your dog will need to take replacement hormones for the rest of their life. Dosage will be monitored and adjusted for the first several months to find the right amount for your dog. Once dosage is stabilized, the typical treatment course involves monthly injections of replacement hormones. In all cases of Addison’s disease, your dog will need treatment to replace corticosteroids (cortisol):
  • Prednisone/prednisolone: Used to replace corticosteroids (cortisol). Frequency and dosage of prednisone varies with each dog. Cortisol plays a role in many important body functions. This includes metabolism, glucose production, blood pressure, anti-inflammatory, red blood cell formation, and response to stress.

In cases of typical Addison’s disease (which is most dogs), treatments will also involve one of these two medications to replace mineralocorticoids:
  • Percorten V or Zycortal: DOCP (desoxycorticosterone) is a long-acting injection which replaces the natural mineralocorticoid hormone, aldosterone. Aldosterone influences the electrolyte balance and fluid balance in the body.
  • Florinef: is a pill given daily to replace the natural mineralocorticoid hormone, aldosterone. Fludrocortisone acetate acts on the kidney to conserve sodium and excrete potassium.

Learn more about the Addison’s research supported by the Foundation.