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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Addison’s disease in cats, also called hypoadrenocorticism, is uncommon, and its early signs are vague enough to be mistaken for many other illnesses. The practical rule is simple: if a cat collapses, is profoundly weak, or looks severely dehydrated or shocked, it needs emergency veterinary care now. Confirming the disease requires adrenal-function testing done by a veterinarian. Once confirmed, it is usually managed with lifelong, veterinarian-directed hormone replacement and regular monitoring. No home test or over-the-counter product can diagnose or cure it.
What Addison’s disease is in cats
The adrenal glands sit near the kidneys. They produce glucocorticoids such as cortisol, which influence energy use, stress response, and blood sugar, and mineralocorticoids such as aldosterone, which help the body hold on to sodium and release potassium. Addison’s disease develops when the adrenal glands do not make enough of these hormones. Because aldosterone affects fluid and electrolyte balance, the illness can disturb hydration, sodium, and potassium levels throughout the body. In a serious case, a sharp rise in potassium can slow the heart or cause an irregular rhythm, which is one reason the condition can become life-threatening.
Causes
In most cats, the exact cause is never identified. Veterinary references describe immune-mediated destruction of the adrenal tissue as the most likely mechanism, but that is an inference about how the gland is damaged rather than a test that can be run on an individual cat. The sources reviewed here also list other possibilities, and they should be read as alternatives rather than a checklist a caregiver can apply at home.
Primary adrenal failure
In primary disease, the adrenal glands themselves are damaged. Immune-mediated destruction is the leading suspicion. Infiltrative disease, including cancer, and trauma to the glands are also listed as possible causes. VCA notes that when an adrenal tumor is the cause, the outlook is worse than in other cases (VCA Animal Hospitals, “Addison’s Disease in Cats”).
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Secondary (pituitary-related) insufficiency
In secondary disease, the adrenal glands are normal but are not stimulated enough because the pituitary gland produces too little ACTH, the hormone that signals the adrenal glands to make cortisol. The distinction matters because the cause, the hormone deficits, and the treatment plan can differ from primary disease, and only a veterinary workup can tell them apart (Veterinary Consulting & Control, “Hypoadrenocorticism (Addison’s Disease) in Cats”).
Medication-associated suppression
Sources describe suppression of the adrenal glands after a course of glucocorticoid or progestin medication, particularly when that medication is stopped abruptly. A cat that has been on steroids can therefore develop signs when treatment ends or is interrupted. This is one of the main reasons steroid doses should never be changed without veterinary advice.
Symptoms
The signs of feline Addison’s disease are nonspecific and often come and go. A cat may seem fine for days, then look unwell again. Many of the same signs appear with kidney disease, gastrointestinal disease, and other endocrine problems, so symptoms alone do not establish a diagnosis.
- Lethargy that waxes and wanes
- Reduced appetite
- Weight loss
- Weakness
- Dehydration
- Vomiting
Diarrhea can occur, but VCA describes it as less typical in cats than in dogs. A cat in a more severe episode may show shock, weak pulses, marked dehydration, a slow heart rate, and profound weakness.
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When signs are an emergency
Treat the following as an emergency and contact an emergency veterinary clinic immediately:
- The cat collapses or cannot stand.
- The cat is profoundly weak or unresponsive.
- Gums look pale or the cat feels cold, and the pulse seems weak.
- The cat is severely dehydrated or has vomited repeatedly and cannot keep fluids down.
Merck describes adrenal crisis as a medical emergency that requires intravenous fluids and correction of fluid, salt, and sugar abnormalities (Merck Veterinary Manual, “Disorders of the Adrenal Glands in Cats”). Do not wait to see whether a crisis passes on its own.
How veterinarians diagnose it
Diagnosis is a process run by a veterinarian, and it generally follows these steps:
- History and physical examination. The vet looks at the timeline of symptoms, any past steroid use, and signs of dehydration, weakness, or abnormal heart rhythm.
- Baseline bloodwork and urinalysis. A complete blood count, chemistry panel, and urinalysis are typically run. Changes in sodium and potassium, along with elevated kidney values, can raise suspicion. These findings are not universal, and kidney disease can produce a similar pattern, so they are clues rather than proof.
- Adrenal function testing. The usual confirmatory test is the ACTH stimulation test. Cortisol is measured before and after an injection of ACTH. A poor cortisol response supports adrenal insufficiency.
- Timing of steroid treatment. VCA notes that steroid treatment is best postponed until after ACTH testing when the cat’s condition allows, because steroids can affect the results. In a crisis, stabilization takes priority, and the vet decides how to sequence testing and treatment.
Addison’s disease should not be diagnosed from symptoms or from a sodium-to-potassium ratio alone. Interpreting these results belongs to the veterinarian.
Treatment
Stabilizing a crisis
A cat in crisis may need hospitalization, intravenous fluid therapy, correction of electrolyte abnormalities, and other supportive care. Stabilization is the first priority, and it is usually urgent. Caregivers should expect that the cat may stay in the clinic for a period of intensive treatment before going home.
Long-term hormone replacement
After stabilization, treatment replaces the missing hormones. Veterinary sources describe glucocorticoid supplementation together with mineralocorticoid replacement when needed. The following options are named in the reviewed references; the veterinarian selects the drug, dose, and schedule for each cat.
| Hormone replaced | Typical role | Options named in the sources |
|---|---|---|
| Glucocorticoid | Replaces cortisol | Glucocorticoid medication prescribed by the veterinarian; specific product and dose not stated in the sources reviewed |
| Mineralocorticoid | Replaces aldosterone, supporting sodium and potassium balance | Oral fludrocortisone, or injectable DOCP; whether a given cat needs mineralocorticoid replacement is decided by the veterinarian (VCA; Merck) |
Monitoring and daily care
Treatment is usually lifelong. Regular veterinary rechecks and blood tests show how well the cat is responding and whether the dose needs adjustment. Rechecks are typically more frequent during the early period of stabilization and regulation, then spaced out once the cat is steady. PetMD also notes that stress or illness may lead the veterinarian to change the dose (PetMD, “Addison’s Disease in Cats”).
At home, the most useful habits are these:
- Give every dose on schedule, and do not skip or stop a steroid without veterinary guidance.
- Keep a written record of doses, appetite, water intake, vomiting, energy level, and any missed doses. This record helps the vet judge response between visits. A simple log or notebook is enough.
- Tell the vet promptly about vomiting, refusal of food, unusual weakness, or a period of stress such as boarding, travel, or surgery, since these may need a dose review.
- Keep an emergency plan and the clinic’s after-hours number on hand, because a relapse can move quickly.
Outlook
With successful treatment of the initial crisis and appropriate long-term therapy, VCA describes the prognosis as generally good, and PetMD describes the long-term outlook with appropriate management as good except where cancer is the underlying cause. These are general statements about the condition, not a guarantee for an individual cat. Outlook is worse when an adrenal tumor is the cause (VCA).
How common is it?
Feline Addison’s disease is considered rare. A 2024 review by Alisdair Boag in the Journal of Feline Medicine and Surgery refers to approximately 40 documented cases in the veterinary literature (Boag, “Hypoadrenocorticism in cats: a 40-year update”). That is a count of reported cases, not an estimate of how many cats have the disease, so it should not be used to judge incidence. Some older web pages cite a smaller figure of fewer than 25 cases. Because that figure is undated and conflicts with the later review, the 2024 count is the more reliable reference.
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