Addison's Disease in Dogs: Signs & Treatment
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Addison's disease (hypoadrenocorticism) is the opposite of Cushing's — the adrenal glands don't make enough of the hormones that regulate salt, water, and the stress response. Signs are often vague and come and go — poor appetite, lethargy, vomiting, weakness — until a sudden, life-threatening Addisonian crisis. Once diagnosed, it's very manageable with lifelong hormone replacement, and most dogs live full, normal lives.
When Addison's becomes an emergency
An Addisonian crisis is a life-threatening emergency. A dog may suddenly collapse, become very weak, vomit, have diarrhea, and go into shock. If your dog collapses or is severely weak and unwell, go to an emergency vet immediately — this crisis is treatable but requires urgent IV fluids and hormones.
Addison's is often called "the great pretender" because its everyday signs mimic many other illnesses and tend to wax and wane. That vagueness means it can go undiagnosed until a stressful event — boarding, travel, illness — tips the dog into a full crisis. Knowing the pattern helps you push for the right test sooner.
What Addison's disease is
The adrenal glands produce two important types of hormone: glucocorticoids (like cortisol, for stress and metabolism) and mineralocorticoids (like aldosterone, which balance sodium and potassium). In Addison's, the adrenal glands are damaged — usually by the dog's own immune system — and can't make enough of these hormones.
The loss of aldosterone is what makes Addison's dangerous: sodium and potassium fall out of balance, which can disturb heart rhythm and blood pressure. It's most often diagnosed in young to middle-aged dogs and tends to affect females more, with certain breeds predisposed.
Signs to watch for
Between crises, the signs are frustratingly nonspecific and often come and go:
- Lethargy and weakness
- Poor or picky appetite and weight loss
- Vomiting and diarrhea, sometimes intermittent
- Increased thirst and urination
- Shaking, and a tendency to get sick around stressful events
Practical take: A pattern of repeated "off" spells that improve with fluids at the vet, then return, is a classic Addison's story. A written log of these episodes can be what finally points to the diagnosis.
How it's diagnosed
Routine bloodwork may show clues — a sodium-to-potassium imbalance, or other changes — but the definitive test is an ACTH stimulation test, which measures whether the adrenal glands can produce cortisol when prompted. In a dog with Addison's, they can't respond normally.
Because early signs are so easily blamed on other problems, sharing the full history of your dog's episodes helps your vet decide to run the specific test rather than treating each flare in isolation.
Treatment and long-term care
The good news: Addison's is one of the more rewarding chronic diseases to manage. Treatment replaces the missing hormones:
- Mineralocorticoid replacement — either a periodic injection (commonly given every few weeks) or a daily oral medication to balance sodium and potassium.
- Glucocorticoid replacement — a low daily dose, increased temporarily during times of stress or illness as your vet directs.
- Regular monitoring — blood tests to fine-tune doses, especially early on.
With consistent medication, most dogs live full, normal lives. The key is never missing doses and giving extra glucocorticoid around known stressors, exactly as your vet instructs. Keeping a record of doses, episodes, and lab results helps keep the plan on track for years.
Keep every dose and episode on record
Tavi logs your dog's medications, off days, and vet results in one place — so intermittent Addison's flares form a visible pattern and lifelong hormone doses never slip. Free for your first pet.
Frequently asked questions
What are the signs of Addison's disease in dogs?
Signs are often vague and come and go: lethargy, weakness, poor appetite, vomiting, diarrhea, and increased thirst. Dogs frequently get sick around stressful events. The dangerous end is an Addisonian crisis, with sudden collapse and shock.
Is Addison's disease in dogs fatal?
An untreated Addisonian crisis can be fatal, but once diagnosed, Addison's is very manageable with lifelong hormone replacement. Most treated dogs live full, normal-length lives with regular monitoring.
Why is Addison's called the great pretender?
Because its everyday symptoms mimic many other diseases and tend to wax and wane, it's easily mistaken for other conditions and often diagnosed late. A specific ACTH stimulation test is what confirms it.
How is Addison's disease in dogs treated?
Treatment replaces the missing adrenal hormones with a mineralocorticoid, given as a periodic injection or daily pill, plus a low daily dose of glucocorticoid that's increased during stress. Regular blood tests fine-tune the doses.
Can a dog with Addison's live a normal life?
Yes. With consistent hormone replacement and monitoring, most dogs with Addison's live normal, active lives. The main responsibilities are never missing medication and giving extra glucocorticoid around stressful events as your vet directs.
Tavi's guides are informational and not a substitute for professional veterinary advice, diagnosis or treatment. When in doubt, call your veterinarian. Sources: Merck Veterinary Manual; VCA Animal Hospitals; American Kennel Club (AKC); Cornell University College of Veterinary Medicine; American Animal Hospital Association (AAHA)