Addison's Disease in Cats: Symptoms and Diagnosis

Name: Addison's Disease in Cats: Symptoms and Diagnosis
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

Addison's disease in cats symptoms are usually subtle and easy to dismiss. Most cats with this rare hormone disorder show vague signs like lethargy, poor appetite, weight loss, and intermittent vomiting or diarrhea that come and go over weeks or months [1]. Because the signs are so nonspecific, diagnosis is often delayed until a crisis develops.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Addison's disease (hypoadrenocorticism) is rare in cats, with only about 40 cases documented in the past 40 years [2].
The most common signs owners notice are lethargy, loss of appetite, weight loss, dehydration, vomiting, and diarrhea [3].
Signs often wax and wane, which is a major reason the condition is missed or mistaken for something else [1].
Diagnosis is confirmed with an ACTH stimulation test, which must be done before starting steroid treatment [4].
Treatment is lifelong but highly successful in most cases, using glucocorticoid and sometimes mineralocorticoid replacement [1].

What Is Addison's Disease in Cats?

Addison's disease, also called hypoadrenocorticism, happens when the adrenal glands do not make enough hormones [3]. The two main hormones involved are glucocorticoids (like cortisol, which helps the body handle stress) and mineralocorticoids (like aldosterone, which controls sodium and potassium balance) [1].

When aldosterone drops, potassium builds up in the blood and sodium falls. In severe cases, high potassium can slow the heart or cause an irregular rhythm [3]. This is why an untreated cat can go from "just a little off" to a life-threatening crisis.

Some cats have only glucocorticoid deficiency without electrolyte problems. This form is sometimes called atypical Addison's disease, and it is likely underdiagnosed because routine blood work looks normal [1].

Addison's Disease in Cats Symptoms: What Owners Notice First

The signs of Addison's disease in cats are frustratingly vague. They rarely point clearly to one organ or one disease. In a review of 41 cats with naturally occurring hypoadrenocorticism, the median age at diagnosis was 5.7 years, with a range from 0.2 to 13.8 years [5].

Common early signs

Lethargy and reduced general condition
Loss of appetite (hyporexia) or complete refusal to eat
Weight loss and gradual loss of body condition [3]
Vomiting and diarrhea [3]
Dehydration
Weakness
Hypothermia (low body temperature)
Constipation or obstipation [6]

Cats with electrolyte abnormalities (low sodium, high potassium, or both) were more likely to be dehydrated, weak, or hypothermic on examination. Interestingly, they were less likely to have a history of vomiting than cats without electrolyte changes [5].

Why the signs are so easy to miss

The clinical signs of hypoadrenocorticism are often vague, can wax and wane over time, and are rarely specific to this disease. They can be present for days, weeks, or months before a diagnosis is made [1]. A cat may seem tired for a few days, perk up, then decline again. Owners often assume it is a passing bug, stress, or just aging.

Some cats show chronic gastrointestinal signs, poor growth, or episodes of hypovolemic shock (collapse from low blood volume) [4]. If your cat has ongoing digestive issues that do not fully respond to treatment, Addison's disease belongs on the list of possibilities. You can read more about overlapping digestive signs in Pancreatitis In Cats Symptoms.

The adrenal crisis

An adrenal crisis is the sudden, severe form of this disease. It can cause shock and signs of kidney failure without much warning [3]. A cat that seemed mildly unwell can collapse and need emergency care within hours. This is the most dangerous stage of Addison's disease.

Causes and Risk Factors

In most cats, the cause is not known, but an autoimmune condition in which the body destroys some of its own tissue is likely [3]. The adrenal glands can also be damaged by cancer elsewhere in the body [3].

A 2022 case report confirmed this autoimmune theory in one cat. Post-mortem examination found lymphoplasmacytic adrenalitis, meaning immune cells had infiltrated the adrenal glands. Staining showed the infiltrate was T-cell rich, which supports an autoimmune cause [7].

Iatrogenic Addison's Disease in Cats

Iatrogenic means the condition was caused by medical treatment. Long-term steroid use can suppress the adrenal glands, and if steroids are stopped abruptly, the glands may not restart hormone production quickly enough. This is called iatrogenic Addison's disease in cats. It is a real risk whenever a cat has been on steroids for a prolonged period, so any taper should be guided by your veterinarian.

Breed and age patterns

British Shorthair cats may be overrepresented among affected cats, so clinicians should be especially alert when this breed shows compatible signs [4]. In one case series of 11 cats, 6 were British Shorthair [6]. Addison's disease has been reported in cats from 2 months to nearly 14 years old, so age alone does not rule it out [5].

A look-alike that is not Addison's disease

Not every cat with low sodium and high potassium has Addison's disease. A 2026 case report described a 1-year-old Maine Coon with severe electrolyte abnormalities and gastrointestinal signs caused by Tritrichomonas foetus infection. ACTH stimulation testing ruled out hypoadrenocorticism, and the electrolytes normalized after antiprotozoal treatment [8]. This is why adrenal function testing matters. A low sodium-to-potassium ratio alone is not a diagnosis.

How Addison's Disease in Cats Is Diagnosed

Diagnosis depends on an accurate history, physical examination, and screening laboratory tests, including a complete blood count, chemistry panel, and urinalysis [1]. Confirmation requires adrenal function testing.

Step 1: Screening blood work

A veterinarian can make a tentative diagnosis based on history, signs, and certain laboratory abnormalities, such as very low sodium and very high potassium levels [3]. Other findings may include azotemia (kidney-related waste products in the blood), hyperphosphatemia, and hypercalcemia [5][9]. None of these findings alone confirms the disease.

Step 2: Baseline cortisol

In clinically stable cats, a baseline cortisol measurement may be used as an initial screening tool [4]. However, no feline-specific thresholds have been validated. The commonly used cutoff of greater than 2 µg/dL (greater than 55 nmol/L) to rule out hypoadrenocorticism should be interpreted with caution in cats, because it may be less reliable than in dogs [4].

Step 3: ACTH stimulation test

The ACTH stimulation test is the definitive test. A low resting cortisol concentration with an inadequate or absent response to synthetic ACTH is diagnostic [2]. This test should be performed before any glucocorticoid treatment is started, because steroids interfere with the results [4].

Various ACTH stimulation testing protocols are reported in published cases, with most using three time-limited blood samples [2]. That can be hard on a sick or stressed cat, so your veterinarian will choose a protocol that balances accuracy with your cat's comfort.

Step 4: Additional testing

Your veterinarian may also use abdominal ultrasound. In one case series, adrenal glands were judged small on ultrasound in 6 of 11 cats [6]. This finding supports the diagnosis but does not replace hormone testing.

Test	What It Shows	Role in Diagnosis
Chemistry panel	Low sodium, high potassium, azotemia, hypercalcemia	Raises suspicion [3][5]
Baseline cortisol	Resting cortisol level	Screening tool in stable cats, interpret with caution [4]
ACTH stimulation test	Adrenal response to synthetic ACTH	Confirms diagnosis [2]
Abdominal ultrasound	Adrenal gland size and shape	Supportive evidence [6]

Conditions that can look similar

A reduced sodium-to-potassium ratio in cats is uncommon and can also occur with severe kidney disease, cardiovascular disease, cavitary effusion, and certain gastrointestinal diseases [8]. If your cat has kidney-related blood work changes, your veterinarian will also consider Symptoms Of Kidney Disease In My Cat and, in older cats, Symptoms Of Kidney Disease In Old Cats.

Treatment Options

Treatment is highly successful but often lifelong [1]. The goal is to replace the hormones the adrenal glands are not making.

Glucocorticoid replacement

Long-term management involves lifelong glucocorticoid replacement, typically using oral prednisolone [4]. Cats generally require higher maintenance doses than dogs [4]. In one case series, the prednisolone maintenance dose was 0.3 mg/kg per day, titrated to the individual cat [6]. Your veterinarian will calculate the exact dose based on your cat's weight, test results, and response to treatment.

Mineralocorticoid replacement

Cats that also lack aldosterone need mineralocorticoid replacement, usually with desoxycorticosterone pivalate (DOCP) injections. Requirements in cats are higher than what is currently used in dogs. A DOCP starting dose of 2.2 mg/kg every 28 days has been reported [6]. Again, your veterinarian sets the dose and interval for your individual cat.

Emergency treatment

An adrenal crisis is a medical emergency. Treatment typically includes intravenous fluids, corticosteroids, and sometimes subcutaneous DOCP [9]. Cats in crisis need hospitalization and close monitoring of electrolytes and heart rhythm.

Treating the whole cat

Some cats have more than one condition. One reported cat was diagnosed with primary hypoadrenocorticism along with exocrine pancreatic insufficiency, cobalamin deficiency, and chronic enteropathy, and later developed diabetes mellitus [7]. If your cat has several ongoing problems, your veterinarian will manage them together.

Recovery, Outlook, and Long-Term Management

Most cats respond well once treatment starts. In one case series, 8 cats were followed for 14 to 70 months, with a median follow-up of 28 months [6]. That is a meaningful stretch of good-quality life for cats with a disease that used to be fatal.

What long-term care looks like

Regular checkups to monitor electrolytes and clinical signs
Periodic dose adjustments as your cat's needs change
Watching for signs of overdose, which can include increased thirst, urination, or appetite
Keeping emergency contact information handy in case of a crisis

Addison's disease in cats life expectancy

Life expectancy varies widely and depends on how quickly the disease is caught, how well your cat responds to treatment, and whether other conditions are present. Some cats live for years after diagnosis [6]. One cat was euthanized 10 months after diagnosis due to status epilepticus that was not linked to glucose or electrolyte abnormalities [7]. That outcome was tied to a separate neurologic event, not to the Addison's disease itself.

Transient cases exist

Not every cat needs lifelong treatment. A 7-week-old kitten was diagnosed with hypoadrenocorticism after surgery and started on treatment. After 3 months, the kitten was doing well on a decreasing glucocorticoid dose, and the care team extended the mineralocorticoid interval while monitoring closely [9]. This suggests some very young cats can have a transient form. Your veterinarian will decide whether a trial reduction is appropriate for your cat.

Prevention

There is no way to prevent the autoimmune form of Addison's disease, since the underlying cause is not controllable [3]. The one preventable form is iatrogenic Addison's disease in cats, which can follow abrupt withdrawal of long-term steroids. If your cat takes steroids for any reason, never stop them suddenly. Follow your veterinarian's tapering plan exactly.

Limitations and When to Contact a Veterinarian

No article can diagnose your cat. Every case needs a veterinarian who can examine your cat, run blood work, and interpret the results in context.

Contact an emergency clinic now if your cat:

Collapses or cannot stand
Breathes rapidly or has a slow, irregular heartbeat
Has severe weakness, tremors, or seems unresponsive
Has repeated vomiting or diarrhea with no interest in water

Contact your veterinarian the same day if your cat:

Has stopped eating for more than 24 hours
Is suddenly much more lethargic than usual
Has vomiting or diarrhea that will not settle
Was recently diagnosed with Addison's disease and seems worse despite treatment

Schedule a routine visit if your cat:

Has had weeks of vague tiredness, weight loss, or poor appetite
Has intermittent digestive signs with no clear cause
Has been on long-term steroids and you are planning to taper them

Frequently Asked Questions

How common is Addison's disease in cats?

It is very rare. Only about 40 cases have been documented in the past 40 years since the disease was first described in cats in 1983 [2]. That rarity is exactly why it gets missed so often.

Can Addison's disease in cats be cured?

Most cases require lifelong treatment, but the disease can be managed very well with hormone replacement [1]. A small number of very young cats may have a transient form that improves over time [9]. Your veterinarian can tell you whether a treatment trial reduction makes sense for your cat.

What is atypical Addison's disease in cats?

Atypical Addison's disease means the cat lacks glucocorticoids but has normal sodium and potassium levels. This form is likely underdiagnosed because routine blood work does not show the classic electrolyte changes [1]. It still requires an ACTH stimulation test to confirm.

Can steroid medications cause Addison's disease in cats?

Yes, this is called iatrogenic Addison's disease. Long-term steroid use can suppress the adrenal glands, and stopping steroids abruptly can leave the body unable to produce enough cortisol. Always taper steroids under veterinary supervision.

Does a low sodium-to-potassium ratio always mean Addison's disease?

No. That ratio can also drop with severe kidney disease, heart disease, fluid in the chest or abdomen, and some gastrointestinal diseases [8]. One reported cat had severe electrolyte abnormalities from a Tritrichomonas foetus infection, and ACTH testing ruled out Addison's disease [8]. Only adrenal function testing can confirm the diagnosis.

References

Addison Disease (Hypoadrenocorticism) in Animals - Endocrine System. Merck Veterinary Manual.
Hypoadrenocorticism in cats: a 40-year update. Journal of feline medicine and surgery, 2024.
Disorders of the Adrenal Glands in Cats - Cat Owners. Merck Veterinary Manual.
Feline hypoadrenocorticism: Emerging insights into clinical features, diagnosis, and treatment. Schweizer Archiv fur Tierheilkunde, 2026.
Clinical findings, treatment, and outcomes in cats with naturally occurring hypoadrenocorticism: 41 cases. Journal of veterinary internal medicine, 2025.
Clinical features and long-term management of cats with primary hypoadrenocorticism using desoxycorticosterone pivalate and prednisolone. Journal of veterinary internal medicine, 2023.
Histopathological evaluation of the adrenal glands in a cat with primary hypoadrenocorticism and multiple endocrine disease. JFMS open reports, 2022.
Hypoadrenocorticism-like syndrome in a cat with Tritrichomonas foetus infection: a case report. The Journal of small animal practice, 2026.
Transient Hypoadrenocorticism in a 7-Week-Old Kitten. Journal of the American Animal Hospital Association, 2025.