Addison’s Disease in Dogs: Symptoms, Diagnosis & Long-Term Management

Addison’s disease — formally known as hypoadrenocorticism — is one of the most frequently misdiagnosed conditions in veterinary medicine. Dogs with Addison’s disease often present with vague, intermittent symptoms that mimic a dozen other conditions: occasional vomiting, episodes of weakness, seeming “off” for a day or two before recovering. Because the symptoms wax and wane, owners and even experienced clinicians can chase the illness for months before a diagnosis is reached. When the diagnosis finally comes, it is often during an Addisonian crisis — a life-threatening collapse that is, paradoxically, also the most classic presentation of the disease.

What Is Addison’s Disease?

The adrenal glands — two small glands that sit near the kidneys — produce hormones that are essential to life. The most critical are:

• Cortisol: a glucocorticoid hormone that regulates metabolism, modulates the immune response, and helps the body handle stress
• Aldosterone: a mineralocorticoid hormone that regulates sodium, potassium, and fluid balance in the body

In Addison’s disease, the adrenal cortex (the outer layer of the adrenal gland) is destroyed — most commonly by an immune-mediated process in which the body attacks its own adrenal tissue. Without cortisol and aldosterone, the dog’s ability to respond to stress is severely compromised, and fluid and electrolyte balance becomes dangerously abnormal.

Addison’s disease is far more common in dogs than cats and is seen more frequently in young to middle-aged female dogs, though it can affect any dog at any age. Certain breeds appear predisposed, including Standard Poodles, Portuguese Water Dogs, Bearded Collies, and Nova Scotia Duck Tolling Retrievers.

What Are the Symptoms of Addison’s Disease in Dogs?

The frustrating hallmark of Addison’s disease is its inconsistency. Dogs are often described by their owners as having “waxing and waning” illness — good days and bad days, seemingly recovering spontaneously before declining again. Typical signs include:

• Lethargy and weakness — often the most prominent complaint
• Vomiting and/or diarrhea
• Poor appetite or anorexia
• Weight loss over time
• Shaking or trembling
• Increased thirst and urination (in some cases)
• Muscle weakness and inability to rise
• Bradycardia (slow heart rate) — caused by dangerously elevated potassium
• Abdominal pain
• Depression

Because these signs appear and resolve without apparent cause, Addison’s disease has earned the nickname “the great imitator” — it can look like gastrointestinal disease, kidney disease, liver disease, or a spinal problem depending on how a given dog presents.

What Is an Addisonian Crisis?

An Addisonian crisis occurs when a dog’s body can no longer compensate for the lack of adrenal hormones — often triggered by a stressful event (illness, surgery, boarding, travel) or simply the cumulative progression of the disease. The dog presents in severe collapse:

• Profound weakness, unable to rise
• Vomiting and diarrhea, sometimes with blood
• Severe dehydration
• Dangerously low blood pressure (shock)
• Severely elevated potassium (hyperkalemia), which can cause fatal cardiac arrhythmias
• Very slow heart rate

An Addisonian crisis is a life-threatening emergency requiring immediate IV fluid therapy and hormone supplementation. Dogs in crisis that receive prompt treatment can make remarkable recoveries. But without treatment, the crisis is fatal.

How Is Addison’s Disease Diagnosed?

The definitive test for Addison’s disease is the ACTH stimulation test. In this test, a baseline cortisol level is measured, synthetic ACTH (adrenocorticotropic hormone) is administered, and cortisol is measured again one hour later. A normal dog’s adrenal glands respond to ACTH by producing significantly more cortisol. A dog with Addison’s disease cannot respond — both baseline and post-stimulation cortisol remain very low.

Blood chemistry abnormalities that suggest Addison’s disease include a characteristic pattern of low sodium and high potassium (though a subset of dogs called “atypical Addison’s” have normal electrolytes and only cortisol deficiency). Our Internal Medicine specialist, Dr. Emily Purswell, DACVIM, is experienced in diagnosing both typical and atypical presentations of hypoadrenocorticism.

How Is Addison’s Disease Treated?

Addison’s disease is a manageable — though not curable — condition. Long-term treatment involves replacing the hormones the adrenal glands can no longer produce:

Mineralocorticoid replacement:

• DOCP (desoxycorticosterone pivalate): an injectable medication given every 25–28 days
• Fludrocortisone (Florinef): an oral medication that provides both mineralocorticoid and some glucocorticoid activity

Glucocorticoid replacement:

• Prednisone or prednisolone: given daily at a low physiologic dose; during periods of stress (illness, surgery, significant life changes), the dose must be temporarily increased — this is called “stress dosing”

With appropriate treatment, most dogs with Addison’s disease have an excellent quality of life and a normal life expectancy. Owners must understand the importance of stress dosing and carry emergency injectable glucocorticoids for situations where the dog becomes severely ill.

When to See a Veterinarian

If your dog has episodes of vomiting, lethargy, or weakness that resolve and recur — particularly if they seem to improve on their own before declining again — Addison’s disease should be on your veterinarian’s diagnostic list. If your dog collapses, cannot rise, or has a very slow heart rate, seek emergency care immediately.

North Springs Veterinary Emergency & Specialty Center’s emergency team is available 24/7 for dogs in Addisonian crisis. Our Internal Medicine specialist, Dr. Emily Purswell, DACVIM, is available Monday through Friday and specializes in complex endocrine and internal medicine conditions. Contact us at , call (719) 920-4430, or email internalmedicine@northspringsvrc.com. Come to 10520 White Diamond Pt, Colorado Springs, CO or call (719) 920-4430.

Sources and Further Reading

1. Feldman EC, Nelson RW. “Hypoadrenocorticism (Addison’s disease).” Canine and Feline Endocrinology and Reproduction. 3rd ed. Saunders; 2004:394–439.
2. Lathan P, Tyler J. “Canine hypoadrenocorticism: diagnosis and treatment.” Compendium on Continuing Education for the Practicing Veterinarian. 2005;27(2):121–131.
3. Oberbauer AM, et al. “Inheritance of hypoadrenocorticism in bearded collies.” American Journal of Veterinary Research. 2002;63(5):643–647.
4. Scott-Moncrieff JC. “Hypoadrenocorticism.” Textbook of Veterinary Internal Medicine. 7th ed. Saunders Elsevier; 2010:1847–1857.
5. American College of Veterinary Internal Medicine. “Hypoadrenocorticism.” ACVIM.org.

This article is written for educational purposes and does not constitute veterinary medical advice. If your pet is experiencing a medical emergency, seek immediate veterinary care.