Addison's Disease in Dogs: Symptoms, Causes and Treatment

Addison's disease is a hormone problem that hides in plain sight. A dog vomits for a day, perks up after a quiet weekend, then gets sick again two weeks later. Each episode looks like a stomach bug.

The good news is that Addison's is very treatable once it's found. The challenge is finding it. Here's what the disease does, who's at risk and how to spot the warning signs.

What is Addison's disease?

Vets call it hypoadrenocorticism. Your dog has two small adrenal glands, one near each kidney. They make cortisol, which helps the body handle stress, and aldosterone, which helps balance salt and water. In Addison's disease the glands stop making enough of these hormones.

Think of cortisol as the body's shock absorber. Without it, even small bumps in the road, like a trip to the kennel, can rattle a dog badly. The AKC puts it this way: without enough cortisol, a dog can't cope with the stresses of everyday life, even small ones.

Why it matters

Aldosterone is the part people forget. It tells the kidneys to hold on to sodium and let go of potassium. Without it, potassium builds up in the blood. High potassium can upset the heart's rhythm, which is one reason a crisis can be so dangerous. The good news is that both hormones can be replaced with medication, so a dog with Addison's can live a normal life.

Addison's versus Cushing's

People often mix up the two. Merck explains that Addison's involves too little adrenal hormone, while Cushing's disease involves too much cortisol. They're opposite problems, though they can share a few signs such as drinking and urinating more. Only blood tests can tell them apart.

What causes Addison's disease in dogs?

In most dogs, the immune system seems to attack and destroy adrenal tissue. VCA calls it immune-mediated destruction. Merck notes the exact cause is often unknown, but an autoimmune process is likely.

Less common causes

Other causes include:

• tumors, infection or injury affecting the adrenal glands
• drugs used to treat Cushing's disease, which can damage the glands
• a pituitary problem, which lowers the signal telling the adrenals to work (secondary Addison's)
• stopping long-term steroid medication too abruptly

Which dogs are at higher risk?

Any dog can get it, including mixed breeds. The AKC stresses that all dogs are at risk. Merck says it's most common in young to middle-aged female dogs. Some breeds appear more often.

• Portuguese Water Dogs
• Standard Poodles
• Bearded Collies
• West Highland White Terriers
• Great Danes
• Leonbergers
• Nova Scotia Duck Tolling Retrievers
• Labrador Retrievers

If you own one of these breeds, it's worth knowing the signs. Recurring stomach upset in a Standard Poodle shouldn't automatically be written off as a sensitive tummy.

Addison's disease symptoms in dogs

The hard part is that no sign points clearly at Addison's. VCA describes the signs as nonspecific and says they may wax and wane. A dog can look like it has a stomach bug, a kidney problem or simply old age.

Common signs

• tiredness or lethargy
• vomiting and diarrhea
• poor appetite or refusing food
• weight loss
• drinking and urinating more
• trembling or shaking
• weakness

Why the signs come and go

Think of a battery that never quite charges. On calm days your dog gets by. On a busy or stressful day, there's nothing in reserve, and the signs flare up.

Often a dog seems worse during or after stressful events, then recovers. Fluids at the vet can also make a dog look better for a while, which can mislead everyone. The AKC notes signs often present sporadically and are easy to mistake for other conditions.

Does Addison's disease come on suddenly?

Mostly no. The glands usually fail gradually, and the early signs are mild. But the disease can turn dangerous quickly, and some dogs first appear at the vet in crisis.

Addisonian crisis

An Addisonian crisis happens when hormone levels fall dangerously low. Potassium rises and sodium falls. VCA describes sudden weakness, severe vomiting and diarrhea, and sometimes collapse. The AKC warns it can lead quickly to shock and complete collapse. Merck says it needs immediate intravenous fluids to restore fluid, salt and sugar levels, and that severe cases can cause heart rhythm problems or shock.

This is an emergency. Don't wait to see if your dog improves overnight. Head to the nearest emergency clinic and tell them you suspect Addison's, or that your dog already has it.

What can set off a crisis

Triggers include stressful events, illness, surgery and missed medication. If your dog has Addison's, call your vet before boarding, travel or anything that will upset the routine. Your vet can advise whether any change to treatment is needed.

How vets diagnose it

Your vet will examine your dog and run blood tests. Clues may include abnormal electrolytes, with high potassium and low sodium, and signs of dehydration. Basic bloodwork can raise suspicion, but it can't confirm Addison's.

The test that settles it is the ACTH stimulation test. VCA calls it the most definitive. Your vet measures cortisol before and after an injection of synthetic ACTH. ACTH is the signal that tells healthy adrenal glands to release cortisol. In a healthy dog, cortisol jumps. In a dog with Addison's, the glands can't respond.

Imaging such as ultrasound may be used to look at the adrenal glands, mostly to rule out other causes.

Treatment for Addison's disease in dogs

Treatment has two parts: stabilizing a dog in crisis, and long-term hormone replacement.

Emergency care

A dog in crisis is hospitalized for intravenous fluids. The goal is to correct fluid, salt and sugar levels and protect the heart. Most dogs improve quickly once treated. The AKC says many bounce back to their old selves shortly after starting treatment.

Lifelong replacement

Once the crisis passes, the routine settles into something predictable. Early on, doses are fine-tuned with repeat blood tests. After that, it can become a simple routine of reminders and regular checkups.

After stabilizing, your dog will need lifelong treatment. Merck is clear on that point. The usual options include:

• DOCP injections (desoxycorticosterone pivalate), given about every 3 to 4 weeks, which replace aldosterone. The AKC notes owners can often give them at home.
• Daily oral glucocorticoids, such as prednisone, which replace cortisol.
• Fludrocortisone tablets, an alternative that supplies both hormones by mouth.

Your vet will recheck electrolytes regularly, especially early on, and adjust doses.

Outlook and living with Addison's disease

The outlook is excellent for most dogs. VCA states the vast majority have a good to excellent prognosis once the diagnosis is made. The AKC says an Addison's dog can live a full and healthy life. The key is never missing doses and keeping up with checkups.

Living with an Addison's dog

Day to day, life looks normal. Keep stress low where you can, and plan ahead for boarding or travel. If your dog has a stomach upset, call your vet early rather than waiting. A dog with Addison's can't easily cope with the extra strain of illness.

How the illness usually unfolds

To see how this looks in practice, picture a three-year-old Standard Poodle. She vomits twice in a week, skips breakfast and sleeps more than usual. Her owner assumes she ate something odd. The vet gives fluids, and within a day she's bouncing around again. Three weeks later, after a weekend at a kennel, she's weak, shaky and vomiting repeatedly.

That pattern is typical. The illness looks like a series of unrelated tummy upsets. The common thread is a dog whose body can't produce enough cortisol to cope with physical or emotional stress. When the vet finally runs electrolytes and an ACTH stimulation test, the cause becomes clear. Once she starts treatment, many dogs in her position return to their normal selves quickly.

Questions to ask your vet

A diagnosis brings a lot of new information. These questions help you feel in control.

• Which medication plan suits my dog: injections, tablets or a mix?
• How often will blood tests be needed, now and later?
• What should I do if my dog vomits or skips a dose?
• Which signs mean I should come in immediately?
• Should we change anything before boarding, travel or a procedure?

Write the answers down and keep them somewhere handy. If another vet ever sees your dog, a clear summary of the diagnosis and medications can matter a lot, especially in an emergency.

Common mistakes owners make

Waiting for the pattern to be obvious

Because signs come and go, many owners put off a visit. It's tempting to wait until the next bad day. If your dog has had two or three unexplained tummy upsets, ask for bloodwork rather than treating each episode on its own.

Stopping or skipping medication

Dogs often look wonderful after a few weeks of treatment. It's easy to think the problem has gone away. It hasn't. The glands still can't make hormones, and replacement is lifelong. Never stop or change doses without talking to your vet.

Assuming it's the same as Cushing's

Both involve the adrenal glands, but the treatments are opposite. A drug used to treat Cushing's can even damage the glands, which Merck lists as one cause of Addison's. Always rely on a vet's diagnosis.

Other conditions can cause similar signs, so dog vomiting and blood in dog stool are worth reading about. Increased thirst also features in kidney disease in dogs. For more, browse our conditions and diseases section.

When to see a vet

• Emergency, right now: sudden weakness, collapse, severe vomiting or diarrhea, or a dog with known Addison's who is unwell after a missed dose.
• Within a day or two: repeated vomiting, diarrhea or poor appetite, especially if it's happened before.
• Book a visit: ongoing tiredness, weight loss, trembling or drinking and urinating more, particularly in an at-risk breed.
• Before planned stress: if your dog has Addison's, call your vet ahead of boarding, travel or surgery.

Tell your vet about the pattern of signs, not just today's. Saying "this is the fourth time in two months" changes how they think about the case.