Addison’s Disease in Dogs – The Great Pretender

Addison’s disease in dogs is a glandular malfunction that comes in both acute and chronic varieties.

By: mootown
Excessive tiredness and increased thirst are just a couple possible symptoms of Addison’s disease. By: mootown

Addison’s disease is a “great pretender.”

It mimics many other conditions and is a favorite condition of mine, as I love the detective work necessary to reach a diagnosis. Best of all, Addison’s patients usually respond well to treatment and go from being sick animals to leading normal lives. How good is that?

Symptoms of Addison’s Disease in Dogs

Dogs with Addison’s come to the clinic with 2 different presentations: chronic (long term) and acute (sudden onset).


Most common are those dogs with chronic, waxing-and-waning symptoms that include:

  • Excessive tiredness
  • Poor appetite
  • Shaking
  • Difficulty jumping up
  • Increased thirst
  • Tummy upsets

Typical of the vague, “chronic” cases was a patient of mine, Daisy. She worried her family when she lost interest in her favorite treats and seemed tired all the time. When Daisy developed diarrhea, her family put the symptoms down to a stomach bug. Although Daisy had some better days, she just wasn’t right.

When she stopped jumping on the sofa for her evening cuddle, the family decided enough was enough and brought her in for a checkup.

Unfortunately, I also see cases (happily, these are rare) of dogs that are rushed to the clinic in a state of collapse. This is the “acute” form of Addison’s, where the dog goes into shock. It is vital that these cases receive aggressive treatment.

What Causes Addison’s Disease?

Addison’s is a disease of young to middle-aged dogs, of which 70% are female. The condition is a lack of production of glucocorticoids and mineralocorticoids (2 forms of natural steroid) from the adrenal gland. These hormones are necessary to regulate the electrolyte balance within the body, which in turn controls blood pressure, muscular function and heart rate.

Researchers think the adrenal gland stops producing these natural steroids because the dog’s own immune system attacks them, otherwise known as auto-immune disease. Rare cases have been found where the dog’s adrenal gland was damaged by a blood clot or a tumor.

A manmade form of Addison’s comes from a dog being on long-term steroids and stopping treatment suddenly. This is because oral steroids suppress the adrenal gland and when the tablets are stopped, the adrenals remain switched off; a few days later, the patient collapses due to steroid deficiency.


Dr. James R. Talbott discusses more information about Addison’s disease in dogs in this video:


Given the vague symptoms of this disease, your vet may suggest running a screening blood panel. Certain shifts on this panel, such as low sodium and chloride with high potassium levels, raise a suspicion of Addison’s. Other clues are present in the blood tests, but the definitive test is an ACTH stimulation test, which measures the ability of the adrenal gland to respond to stimulation.


A collapsed Addisonian dog is an emergency and requires aggressive fluid therapy plus intravenous doses of steroid.

Cases such as Daisy, who are vaguely unwell, usually respond well to oral supplementation of the mineralocorticoids and glucocorticoid that they lack in the form of tablets, given twice a day. Your vet will monitor the dog’s electrolyte levels and adjust the dose of drugs accordingly. Some dogs tend to leach sodium out in the urine; by adding salt to the diet, this loss can be corrected. Salt, hand in hand with medication, helps get the dog back to full health.

How to Prevent Addison’s Disease

Addison’s is a glandular malfunction, so there is no effective prevention other than to be alert for signs of chronic ill health in your pet and to seek veterinary advice.


  • Clinical Medicine in the Dog and Cat. Michael Schaer. Manson Publishing.


This pet health content was written by a veterinarian.


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