Dog Addison's Disease: Symptoms, Diagnosis, and Treatment
Addison's disease — hypoadrenocorticism — happens when a dog's adrenal glands stop producing enough cortisol and (usually) aldosterone, and it is famously called the great pretender because the signs come and go. Roughly 70 to 75 percent of affected dogs are female and most are under 7 years old at diagnosis (Klein & Peterson, 2010, J Vet Intern Med). An Addisonian crisis — collapse, slow heart rate, and dangerously high potassium — kills within hours if untreated, but dogs caught and started on monthly DOCP and daily prednisone live a normal lifespan.
Last reviewed: June 2026
What Addison's Disease Actually Is
The adrenal cortex makes two critical hormones: cortisol, which handles stress, sugar balance, and blood pressure; and aldosterone, which controls sodium, potassium, and fluid balance. In typical Addison's both fail (primary hypoadrenocorticism), usually because the immune system has destroyed the adrenal cortex. A subset of dogs lose only cortisol (atypical Addison's). Cortisol withdrawal makes the dog vague and unwell; aldosterone failure drives sodium down, potassium up, and dehydration through the roof — and that combination causes the crisis form. The 2018 ACVIM consensus describes hypoadrenocorticism as relatively rare but underdiagnosed because the signs are so easy to attribute to gastroenteritis (Lathan & Thompson, 2018, Vet Med Res Rep).
Why It Is Called the Great Pretender
Most dogs do not arrive in crisis. They arrive with a story: 'She had a vomiting and diarrhea episode 6 weeks ago, was fine for a month, and now she is off her food again.' The waxing-waning pattern — usually triggered by minor stress like boarding, a thunderstorm, or a hike — is the single most useful clue. Younger Standard Poodle, Portuguese Water Dog, Nova Scotia Duck Tolling Retriever, West Highland White Terrier, and Bearded Collie are over-represented breeds with a documented genetic predisposition. The 2010 series of 225 dogs found a median age at diagnosis of 4 years and 70 percent female (Klein & Peterson, 2010, J Vet Intern Med).
Common Signs Owners Notice
Vague lethargy, reduced appetite, intermittent vomiting, watery diarrhea (sometimes bloody), shivering, and weight loss are the classic mix. About 30 percent of dogs lose more than 10 percent of body weight over a few months. Episodes often resolve on their own when supportive fluids are given, which fools owners and vets into thinking it was just gastroenteritis. The crisis presentation looks different: collapse, profound weakness, slow heart rate, cold extremities, and a tense painful abdomen — a dog who walked into the lobby and is now flat on the floor.
Bloodwork Clues Before the ACTH Stim
Several patterns on a routine blood panel are enough to push your vet to test for Addison's the same visit. A sodium to potassium ratio under 27 is highly suspicious — normal dogs sit at 30 or higher. Mild non-regenerative anemia, low cholesterol, low albumin, and a high BUN with a normal creatinine are also classic. The absence of a stress leukogram (no high white count, no high neutrophils) in a clearly sick dog is a soft clue that cortisol is missing. A 2018 review noted that any combination of these findings should prompt an ACTH stimulation test rather than presumptive treatment for 'gastroenteritis' (Lathan & Thompson, 2018, Vet Med Res Rep).
How Addison's Is Diagnosed
The ACTH stimulation test is the gold standard. A baseline cortisol is drawn, synthetic ACTH is given, and a second cortisol is drawn 60 minutes later. A normal dog mounts a robust cortisol response. An Addisonian dog stays flat — usually under 2 micrograms per deciliter at both time points. A resting cortisol of more than 2 micrograms per deciliter on a screening panel essentially rules out Addison's, which makes the resting cortisol a useful and inexpensive screen before committing to the full stim test. Imaging is not required for diagnosis but adrenal ultrasound often shows small adrenals.
Treatment: DOCP, Prednisone, and a Long Normal Life
Treatment replaces the missing hormones. Most dogs receive DOCP (desoxycorticosterone pivalate) by injection every 25 to 30 days, which replaces aldosterone, plus daily oral prednisone at a low dose for cortisol. Atypical Addisonians (cortisol-only) get just the prednisone. Dose is titrated to electrolytes and how the dog feels. Owners are taught to double or triple the prednisone dose around predictable stressors — boarding, surgery, thunderstorms — to prevent crisis. With proper management, dogs live a normal lifespan and prognosis is excellent, per the 2018 review.
Crisis Management
An Addisonian crisis is a true emergency. Treatment in the ER is aggressive IV fluids (often saline at a high rate), IV dexamethasone (which does not interfere with the ACTH stim test if drawn early), and aggressive correction of hyperkalemia with calcium gluconate, dextrose, and insulin if the cardiac rhythm is unstable. Most dogs respond within hours. Once stable, DOCP and prednisone are started for life. Survival of the first crisis with appropriate ER care is roughly 90 percent, but dogs misdiagnosed as gastroenteritis and sent home can deteriorate within 12 to 24 hours.
When to See a Vet
Call your vet today if:
- Recurrent episodes of vomiting, diarrhea, or off-food that come and go over weeks
- A dog who feels good for a week, then crashes after boarding, a hike, or thunderstorms
- Mild but persistent shivering, weakness, or weight loss without a clear cause
- Lab results showing a sodium to potassium ratio under 27 or mild non-regenerative anemia
- A young to middle-aged Standard Poodle or Nova Scotia Duck Tolling Retriever with vague illness
Go to the ER immediately if:
- Collapse or sudden inability to stand
- Profound weakness, pale gums, and a slow heart rate
- A dog with known Addison's who has vomited more than twice or missed a DOCP dose
- Known Addisonian who has not held down prednisone for 24 hours
- Severe dehydration, ice-cold extremities, or unresponsiveness
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Frequently Asked Questions
How do I know if my dog has Addison's vs. just an upset stomach?
Addison's is suggested by a pattern of waxing and waning illness, especially with stress triggers. A single episode that resolves on supportive care could still be Addison's. Ask your vet to run an electrolyte panel and a resting cortisol if your dog has had more than one episode of vague illness; a resting cortisol over 2 essentially rules it out.
How much does diagnosis and treatment of Addison's cost?
Initial vet exam runs $50 to $150 in the US. Bloodwork and electrolytes add $150 to $300. An ACTH stim test costs $200 to $400. Hospitalization for an Addisonian crisis ranges $1,500 to $5,000 at a general practice or ER. Once diagnosed, monthly DOCP injections are typically $50 to $120, and daily prednisone is under $20 per month. Lifelong management is far cheaper than repeated ER visits for missed diagnoses.
What is the life expectancy of a treated Addisonian dog?
With proper DOCP and prednisone dosing, life expectancy is essentially normal. Most studies show that survival drops only when crises are missed or when owners cannot afford monthly DOCP. The biggest risk is a missed dose during a stressful event, so stress-dose prednisone training matters more than fancy monitoring.
Can Addison's be cured?
No. The adrenal cortex is destroyed and does not regenerate. But it is fully managed with hormone replacement. Dogs on stable DOCP and prednisone live the same lifespan as unaffected dogs of the same breed.
Why is Addison's so commonly missed?
Because the signs mimic gastroenteritis, pancreatitis, kidney disease, and inflammatory bowel disease, and because the episodes self-resolve with fluids. A dog who improves on IV fluids and goes home feels better not because the gastroenteritis is gone but because cortisol effects of dexamethasone or fluid resuscitation masked the underlying problem. The pattern of recurrence is the giveaway.
Is Addison's hereditary?
Yes in specific breeds: Standard Poodles, Portuguese Water Dogs, Nova Scotia Duck Tolling Retrievers, Bearded Collies, and Leonbergers have documented heritability. Affected breeding lines should not be bred forward. Most other breeds get sporadic immune-mediated Addison's without a clear family pattern.
What is atypical Addison's?
Atypical Addison's is loss of cortisol only, with normal aldosterone and normal electrolytes. These dogs look chronically unwell — poor appetite, weight loss, occasional GI signs — but never develop the crisis hyperkalemia pattern. Diagnosis requires the ACTH stim because the standard electrolyte clues are absent. Treatment is daily prednisone only.
Can stress trigger a crisis in a stable Addisonian?
Yes. Boarding, surgery, thunderstorms, long car trips, and even an aggressive game of fetch in heat can trigger crisis. Owners are taught to double or triple the daily prednisone dose 1 to 2 days before and after a known stressor. If a stable dog vomits, becomes weak, or has diarrhea, the ER plan is to give injectable steroids and fluids immediately rather than wait.
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