What are the symptoms of Addison's disease in dogs?

Symptoms are often vague, intermittent, and easily mistaken for other conditions — which is why Addison's is called 'the great pretender.' Common signs include: recurrent vomiting and diarrhea, lethargy and weakness (especially after stress), poor appetite and weight loss, shaking or trembling, and occasional improvement with IV fluids. A key pattern is that symptoms wax and wane — the dog seems to recover, then deteriorates again. An Addisonian crisis is the acute, severe form: sudden collapse, profound weakness, bradycardia (slow heart rate), shock, and inability to stand.

What does bloodwork show in a dog with Addison's disease?

The most characteristic finding is hyponatremia (low sodium) combined with hyperkalemia (high potassium). A sodium-to-potassium ratio (Na:K) below 27 — especially below 24 — is a classic flag for Addison's. Other common findings include elevated BUN and creatinine (from poor perfusion and dehydration), mild hypoglycemia, mild non-regenerative anemia, and a normal or 'reverse' white cell count (lymphocytosis and eosinophilia) — the opposite of the stress leukogram seen in other sick dogs. Absence of a stress leukogram in a sick, stressed dog is itself a clue that Addison's may be present.

How is Addison's disease treated in dogs?

An Addisonian crisis is treated as an emergency: IV saline (0.9% NaCl) to correct electrolytes and support blood pressure, dexamethasone for immediate glucocorticoid replacement (does not interfere with ACTH stim testing), and dextrose if blood sugar is low. Long-term management uses: (1) DOCP (desoxycorticosterone pivalate / Percorten-V) — an injectable mineralocorticoid given every 25–28 days to replace aldosterone; and (2) daily oral prednisone at a low dose to replace cortisol. Alternatively, oral fludrocortisone (Florinef) covers both mineralocorticoid and glucocorticoid functions in one daily tablet, though some dogs need supplemental prednisone as well.

Can dogs with Addison's disease live a normal life?

Yes — with proper management, dogs with Addison's disease typically have an excellent prognosis and a normal lifespan. Most dogs stabilize quickly once the correct medication and dosing is established. The main ongoing considerations are: never missing a DOCP injection, increasing the prednisone dose during illness or stress ('stress dosing'), wearing a medical alert tag, and regular bloodwork to check electrolytes and kidney values. Dogs that receive consistent treatment do very well and owners often report their dog is completely back to normal.

Addison's Disease in Dogs: Symptoms, Diagnosis & Treatment (2026)

Q: What is Addison's disease in dogs?

Addison's disease (hypoadrenocorticism) is a condition where the adrenal glands fail to produce sufficient cortisol (a glucocorticoid) and usually aldosterone (a mineralocorticoid) as well. It is the opposite of Cushing's disease, which involves excess cortisol. Without these hormones, the body cannot regulate stress responses, blood pressure, electrolytes, or blood sugar properly. The most common cause in dogs is immune-mediated destruction of the adrenal cortex, though it can also follow abrupt withdrawal of long-term steroid treatment or medications like trilostane and mitotane.

Quick Facts: Addison's Disease in Dogs

What it is: Adrenal gland failure — too little cortisol and usually too little aldosterone. The opposite of Cushing's disease.
Classic bloodwork flag: Low sodium + high potassium. Na:K ratio below 27 — especially below 24 — is a strong indicator.
The great pretender: Waxing-and-waning GI signs, weakness, and lethargy that repeatedly improve with fluids and then return — until a crisis hits.
Addisonian crisis: Sudden collapse, bradycardia, and shock — a life-threatening emergency requiring immediate IV fluids and glucocorticoids.
Diagnosis: ACTH stimulation test — cortisol fails to rise after synthetic ACTH injection.
Treatment: DOCP injection every 25–28 days (mineralocorticoid) + daily oral prednisone (glucocorticoid).
Prognosis: Excellent — most dogs live completely normal lives with consistent management.

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Addison's disease is one of veterinary medicine's most reliably misdiagnosed conditions — not because it's obscure, but because its symptoms come and go, mimic a dozen other problems, and then temporarily improve with supportive care. By the time a dog collapses in an Addisonian crisis, weeks or months of GI signs may already have been attributed to dietary indiscretion, stress, or a sensitive stomach. Here's what Addison's actually looks like, what the bloodwork reveals, and what long-term management involves.

What Is Addison's Disease?

Addison's disease — medically called hypoadrenocorticism — is the failure of the adrenal glands to produce adequate amounts of their essential hormones. The adrenal cortex normally produces two critical hormone classes:

Glucocorticoids (primarily cortisol)

Regulate metabolism, blood glucose, immune function, and the body's response to physical and emotional stress. Without cortisol, a dog cannot mount a normal stress response — minor physical challenges (a vet visit, a car ride, an upset stomach) become destabilizing events.

Mineralocorticoids (primarily aldosterone)

Regulate sodium and potassium balance through the kidneys. Aldosterone tells the kidney to retain sodium and excrete potassium. Without it, sodium is lost in urine and potassium accumulates in the blood — producing the characteristic electrolyte pattern of Addison's disease and, in severe cases, dangerously slow heart rhythms from hyperkalemia.

Typical vs. Atypical Addison's

Most dogs with Addison's have typical hypoadrenocorticism — deficiency of both cortisol and aldosterone, producing the classic electrolyte abnormalities. About 30–40% of dogs have atypical hypoadrenocorticism — glucocorticoid deficiency only, with normal electrolytes. Atypical Addison's is particularly easy to miss because the Na:K ratio is normal, and the diagnosis requires direct cortisol testing rather than being flagged by routine bloodwork. Some atypical dogs eventually develop mineralocorticoid deficiency over time.

Causes

•Immune-mediated destruction (most common): The immune system attacks and destroys the adrenal cortex. This is the cause in the majority of spontaneous Addison's cases. No identifiable trigger is found.
•Iatrogenic — abrupt steroid withdrawal: Dogs on long-term corticosteroids can develop HPA axis suppression. Sudden discontinuation leaves the adrenal glands unable to produce cortisol independently. This is why steroids must be tapered, not stopped abruptly.
•Iatrogenic — over-treatment of Cushing's: Trilostane or mitotane used to treat Cushing's disease can over-suppress the adrenal glands. This is a known complication requiring monitoring with ACTH stimulation tests.
•Adrenal gland hemorrhage or infarct: Rarely, trauma, coagulopathy, or tumor hemorrhage destroys adrenal tissue bilaterally.
•Granulomatous disease or metastatic cancer: Bilateral adrenal infiltration can rarely cause Addison's, though this is uncommon.

Which Dogs Are Most at Risk?

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Age: Typically young to middle-aged dogs, most commonly 4–7 years old. Unlike Cushing's disease, Addison's frequently affects younger animals.
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Sex: Females are overrepresented — approximately 70% of affected dogs are female, suggesting a hormonal or immune influence.
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Predisposed breeds: Standard Poodle, Portuguese Water Dog, Bearded Collie, Soft Coated Wheaten Terrier, Great Dane, West Highland White Terrier, Rottweiler, Nova Scotia Duck Tolling Retriever. Standard Poodles are significantly overrepresented and may have a hereditary component.
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Any breed can be affected: Despite breed predispositions, Addison's occurs across all breeds and mixed-breed dogs. The diagnosis should be considered in any dog with recurrent GI signs and unexplained deterioration.

Symptoms of Addison's Disease in Dogs

Addison's is called "the great pretender" because its symptoms overlap with many common conditions and tend to come and go — partially resolving with supportive care (IV fluids, anti-nausea medication) before returning. This pattern is the key clinical clue.

Chronic / Waxing-Waning Signs

•Episodic vomiting and/or diarrhea: Often attributed to dietary indiscretion or a sensitive GI tract. The dog recovers, then has another episode weeks later.
•Lethargy and weakness: Variable energy — sometimes normal, sometimes profoundly tired, especially after any stressor.
•Poor appetite and weight loss: Gradual loss of condition over weeks to months.
•Shaking or muscle tremors: From weakness and electrolyte disturbance.
•Increased thirst and urination: Sodium wasting drives some PU/PD, though less dramatically than in Cushing's or diabetes.
•Abdominal pain: Some dogs are painful on palpation of the abdomen.
•Temporary improvement with fluids: The dog bounces back on IV fluids and then deteriorates again days to weeks later — this pattern should always prompt Addison's testing.

Warning

The Addisonian Crisis — A True Emergency

An Addisonian crisis occurs when the adrenal glands are completely unable to support the body, usually triggered by a stressor (illness, surgery, boarding, travel). Signs: sudden profound weakness or collapse, inability to stand, slow heart rate (bradycardia from severe hyperkalemia), low blood pressure, cold extremities, and shock. This is immediately life-threatening and requires emergency IV fluids, glucocorticoids, and electrolyte correction. Go to an emergency vet immediately.

Bloodwork Findings in Addison's Disease

Routine bloodwork often provides the first strong clue, even before specific hormone testing is ordered. If you want a reference for what each value means, see our guide to reading dog blood test results.

Test	Finding	Why
Sodium (Na)	Low (hyponatremia)	Aldosterone deficiency → kidneys cannot retain sodium → sodium lost in urine
Potassium (K)	High (hyperkalemia)	Aldosterone deficiency → kidneys cannot excrete potassium → builds up in blood
Na:K ratio	<27 (often <24)	The single most useful screening number — normal is 27–40; below 27 warrants ACTH testing
BUN / Creatinine	Elevated	Prerenal azotemia from dehydration and poor perfusion; usually resolves with fluids
Blood glucose	Low-normal or mildly low	Cortisol deficiency → reduced glucose production and counterregulation
CBC — leukogram	Lymphocytosis + eosinophilia	No stress leukogram despite being very sick — cortisol deficiency means the normal stress response is absent. This is a critical clue.
Calcium	Mildly elevated in ~30%	Mechanism not fully understood; resolves with treatment
Albumin	Low in some cases	GI protein loss from chronic vomiting/diarrhea

Note

The Absent Stress Leukogram — A Key Clue

Any sick, stressed dog should have a stress leukogram on their CBC: high neutrophils, low lymphocytes, low eosinophils. If a dog is clearly unwell but the CBC shows normal or increased lymphocytes and eosinophils — the opposite of what stress should produce — this is a strong indicator that cortisol is deficient and Addison's should be tested for immediately.

How Vets Diagnose Addison's Disease

ACTH stimulation test — the gold standard

Diagnosis is confirmed by demonstrating that the adrenal glands cannot produce cortisol. The ACTH stimulation test does this directly:

1.A baseline blood sample is drawn and cortisol measured.
2.Synthetic ACTH (cosyntropin) is injected intravenously or intramuscularly.
3.A second blood sample is taken 60 minutes later and cortisol remeasured.

In a healthy dog, cortisol rises substantially after ACTH stimulation — typically above 6–17 µg/dL post-stimulation. In a dog with Addison's disease, both the baseline and post-ACTH cortisol remain very low (usually below 2 µg/dL) because the damaged adrenal cortex cannot respond. The test takes approximately 60–90 minutes and can be run during an emergency presentation.

Resting cortisol as a screen

A single resting (basal) cortisol below 2 µg/dL is highly suggestive of Addison's and in a clinically appropriate context may be enough to begin empirical treatment. A resting cortisol above 2 µg/dL makes Addison's much less likely. This can be a useful rapid screen when the full ACTH stim test is not immediately possible.

Differentiating typical from atypical Addison's

If the ACTH stim confirms hypoadrenocorticism but the electrolytes are normal (Na:K ratio normal), the dog has atypical Addison's — glucocorticoid deficiency without mineralocorticoid deficiency. These dogs need cortisol replacement (prednisone) but not necessarily mineralocorticoid treatment at diagnosis, though monitoring over time is important since some develop mineralocorticoid deficiency later.

Treatment of Addison's Disease in Dogs

Emergency treatment of an Addisonian crisis

An Addisonian crisis is treated aggressively with:

•IV saline (0.9% NaCl): The cornerstone of treatment. Rapidly corrects sodium, dilutes potassium, supports blood pressure, and restores perfusion. Often produces dramatic clinical improvement within hours.
•Dexamethasone: Provides immediate glucocorticoid replacement without interfering with the ACTH stimulation test — critically important, as dexamethasone is not detected by the cortisol assay. Given IV while the ACTH stim is run simultaneously.
•Dextrose: Added to IV fluids if the dog is hypoglycemic.
•ECG monitoring: Severe hyperkalemia can cause life-threatening cardiac arrhythmias. Continuous monitoring is standard in a crisis, and if dangerous arrhythmias are present, calcium gluconate or sodium bicarbonate may be given to protect the heart while the potassium is being corrected by fluids.

Long-term maintenance: the two-drug approach

Once stable, long-term management replaces both hormones the adrenal glands are no longer producing:

DOCP (Percorten-V / desoxycorticosterone pivalate) — mineralocorticoid

An injectable mineralocorticoid given subcutaneously or intramuscularly every 25–28 days. Replaces aldosterone — controls sodium and potassium balance. The dose is adjusted based on electrolyte checks at each injection visit. This is the preferred mineralocorticoid in most hospital settings because it has no glucocorticoid activity (so prednisone dosing can be managed independently) and is given monthly rather than daily. Cost is a consideration — Percorten-V injections can be $80–200+ per dose depending on the dog's size and region.

Prednisone — glucocorticoid

Given orally once daily at a low physiologic dose (typically 0.1–0.2 mg/kg/day). Replaces cortisol. The dose is kept as low as possible to avoid iatrogenic Cushing's signs (excessive thirst, weight gain, pot belly). Dose is increased two to three times during illness, surgery, travel, or any major stressor — this is called "stress dosing" and is essential for preventing a crisis during times when cortisol demand is elevated.

Fludrocortisone (Florinef) — alternative to DOCP

An oral medication that provides both mineralocorticoid and glucocorticoid activity. Given once or twice daily. Simpler for owners who find daily tablets easier than monthly injections, and less expensive per dose. However, separating mineralocorticoid and glucocorticoid doses is more precise with the DOCP + prednisone combination. Some dogs on fludrocortisone still need supplemental prednisone. Both approaches are clinically acceptable.

Stress dosing — critical owner knowledge

Under normal conditions, a healthy dog's adrenal glands can increase cortisol output by three to five times during illness or stress. A dog with Addison's cannot do this. The daily prednisone dose only covers baseline needs — during any significant stressor, it must be temporarily increased.

Stress dose triggers include: illness with vomiting or diarrhea, surgery or anesthesia, trauma, boarding, travel, and any situation causing significant physical or emotional stress. Most vets recommend doubling or tripling the daily prednisone dose for the duration of the stressor and returning to the maintenance dose once the dog is well. If a dog with Addison's is unable to take oral medication (e.g. vomiting), injectable glucocorticoids must be given — this requires an emergency vet visit.

Warning

Never Stop Prednisone Abruptly or Miss a DOCP Injection

Addisonian dogs depend on their medication to survive. Missing a DOCP injection by several days, stopping prednisone suddenly, or failing to stress-dose during illness can precipitate a life-threatening crisis. Always carry an emergency injectable glucocorticoid kit if recommended by your vet, and make sure all caregivers understand the medication schedule and the warning signs of a crisis.

Long-Term Monitoring

Once stabilized on the correct medication doses, most Addisonian dogs require routine rechecks every 3–6 months:

•Electrolytes at each DOCP injection: Sodium and potassium checked before each monthly injection to assess whether the DOCP dose is appropriate. The Na:K ratio should normalize to >27 on correct dosing.
•Kidney values: BUN and creatinine to ensure the prerenal azotemia from the initial presentation has resolved and remains stable.
•Clinical assessment: Body weight, muscle condition, thirst and urination levels, energy — to ensure the prednisone dose isn't too high (causing Cushing's-like signs) or too low (inadequate cortisol replacement).
•Annual comprehensive bloodwork: Full chemistry panel and CBC once a year.

Prognosis

The prognosis for Addison's disease in dogs is excellent. With appropriate medication, most dogs return to completely normal activity, appetite, and quality of life within days to weeks of starting treatment. Studies have found that survival times for treated Addisonian dogs are not significantly different from the general dog population — meaning the disease does not substantially shorten lifespan when well managed.

The main risks are: a crisis triggered by missed medication or inadequate stress dosing, and the financial and logistical commitment of lifelong monthly injections and periodic bloodwork. Owners who understand the disease, carry emergency supplies, and maintain consistent medication schedules typically have extremely good long-term outcomes.

Frequently Asked Questions

What is Addison's disease in dogs?

Addison's disease (hypoadrenocorticism) is adrenal gland failure — the adrenal glands cannot produce sufficient cortisol (glucocorticoid) and usually aldosterone (mineralocorticoid). It is the opposite of Cushing's disease. Without these hormones, dogs cannot regulate stress responses, electrolytes, blood pressure, or blood glucose properly. The most common cause is immune-mediated destruction of the adrenal cortex.

What does a low Na:K ratio mean in dogs?

A sodium-to-potassium (Na:K) ratio below 27 — especially below 24 — is a classic finding in Addison's disease. Aldosterone normally tells the kidneys to retain sodium and excrete potassium. Without it, sodium is lost and potassium accumulates. The Na:K ratio is calculated by dividing the blood sodium value by the potassium value. A low ratio in a dog with GI signs, lethargy, or weakness should prompt immediate ACTH stimulation testing.

What is an Addisonian crisis?

An Addisonian crisis is an acute, life-threatening emergency where the adrenal glands completely fail to support the body, usually triggered by a stressor. Signs include sudden profound collapse, inability to stand, slow heart rate (bradycardia from severe hyperkalemia), cold extremities, and shock. Treatment requires emergency IV saline, glucocorticoids (dexamethasone), and cardiac monitoring. Without treatment it is fatal.

How is Addison's disease diagnosed in dogs?

Diagnosis is confirmed with an ACTH stimulation test. A baseline cortisol is measured, synthetic ACTH is injected, and cortisol is remeasured 60 minutes later. In Addison's, both the baseline and the post-ACTH cortisol are very low — the adrenal glands cannot respond. A resting cortisol below 2 µg/dL is also highly suspicious and may prompt empirical treatment while results are awaited.

What is the treatment for Addison's disease in dogs?

Long-term management requires: (1) DOCP (Percorten-V) — an injectable mineralocorticoid given every 25–28 days to replace aldosterone and control sodium/potassium balance; and (2) daily oral prednisone at a low physiologic dose to replace cortisol. Alternatively, oral fludrocortisone covers both functions. During illness or stress, the prednisone dose must be doubled or tripled ('stress dosing') — this is critical and cannot be skipped.

Can dogs with Addison's disease live normal lives?

Yes — the prognosis is excellent. Studies show treated Addisonian dogs have survival times comparable to healthy dogs of the same age and breed. Most dogs return to completely normal energy, appetite, and activity within days to weeks of starting treatment. The key commitments are consistent monthly injections, daily medication, stress dosing when ill, and regular electrolyte checks.

Want to understand your dog's electrolyte and bloodwork results?

Upload your dog's chemistry panel or CBC — VetLens explains every value in plain language, flags abnormal sodium and potassium, and helps you track changes at each vet visit.