Addison's Disease in Dogs: Signs, Crisis and Treatment

What Addison's disease is

The adrenal glands sit near the kidneys and make two hormones that matter here. Cortisol helps the body cope with stress, illness and blood sugar control. Aldosterone keeps sodium and potassium in balance, which in turn controls fluid levels, blood pressure and the heart's rhythm. In Addison's disease, which vets call hypoadrenocorticism, the outer layer of the glands is usually destroyed by the dog's own immune system, so too little of these hormones is made.

VCA notes less common causes, including damage from infection, cancer or trauma, a pituitary problem, treatment for Cushing's disease, and suddenly stopping long-term steroid medicine. The Merck Veterinary Manual says the condition is most common in young to middle-aged dogs, especially young adult females, and VCA lists breeds at higher risk, including Standard Poodles, Portuguese Water Dogs, Bearded Collies, Nova Scotia Duck Tolling Retrievers, Great Danes, Leonbergers and Labrador Retrievers.

Signs of Addison's disease in dogs

Addison's is sometimes called the great pretender because its signs are vague and often come and go. A dog may have bouts of vomiting or diarrhea, a poor or picky appetite, lethargy, shaking or trembling, weakness, increased thirst and urination, and gradual weight loss. Signs often seem worse after a stressful event such as boarding, travel, a move or surgery, and then improve for a while.

Because these signs overlap with many common problems, from an upset stomach to kidney disease, dogs are often treated for something else before Addison's is suspected. A pattern of repeated stomach upsets in a young dog, especially one that bounces back quickly with fluids from the vet, is a reason to ask whether Addison's has been ruled out. A very slow heart rate is another clue your vet may notice.

When to call your vet today

Call your vet the same day if your dog has vomiting or diarrhea along with marked tiredness, weakness or trembling, or if it has had several episodes of tummy upset over weeks or months without a clear cause. Mention any weight loss, increased drinking, and whether signs flared after stress.

If your dog has already been diagnosed with Addison's, call your vet promptly when it seems off, refuses food, vomits or has diarrhea, or when a stressful event is coming up such as surgery, boarding or travel. Never stop or skip prescribed hormone medicine, and do not change the timing without your vet's advice.

When it's an emergency

An Addisonian crisis is a medical emergency. Go to your vet or the nearest emergency vet immediately if your dog suddenly becomes very weak, cannot stand, collapses, has severe vomiting or diarrhea, especially with blood, has pale gums, feels cold, or has a very slow or irregular heartbeat. The Merck Veterinary Manual warns that shock and kidney failure can develop suddenly.

In a crisis, high potassium can disturb the heart's rhythm and low sodium and dehydration can drop blood pressure dangerously. Do not wait to see whether your dog improves overnight. Keep it warm and quiet, carry it if needed, and call ahead so the hospital is ready.

What you can safely do at home

At home, the most useful thing is careful observation. Note when signs start and stop, what your dog ate, changes in drinking and urination, its weight, and any stressful events. That history often helps your vet recognize the pattern. Keep fresh water available and offer small meals, but do not force food on a dog that is vomiting.

Do not give human medicines, leftover steroids or supplements to try to help. Steroid medicines interfere with the test used to diagnose Addison's, and the wrong medicine can be dangerous. For a diagnosed dog, keep a written list of its medicines and your vet's emergency number handy, and ask your vet whether it needs extra support around stressful events.

Keep fresh water available at all times, and an automatic water dispenser helps make sure the bowl never runs dry.

What the vet will likely check

Routine blood and urine tests often give the first clue, particularly low sodium and high potassium, though some dogs have normal electrolytes. The confirming test is an ACTH stimulation test: your vet measures cortisol in the blood, gives an injection of a hormone that should make the adrenal glands respond, and measures cortisol again. A dog with Addison's has low cortisol and little or no response.

A dog in crisis is hospitalized for intravenous fluids to correct dehydration, sodium, potassium and blood sugar, along with hormone replacement once stabilized. Long-term treatment is lifelong hormone replacement, by injection, tablets or both, with regular blood tests so your vet can adjust it. VCA reports that the vast majority of dogs have a good to excellent outlook once stabilized, and most return to normal, active lives.

Living with a dog with Addison's

Addison's cannot be prevented, but its dangers can. Give medicine exactly as prescribed, keep recheck appointments, and stock up so you never run out. Some owners learn to give the regular injection at home, while others prefer to visit the clinic; your vet can help you choose.

Tell every vet, groomer, boarding facility and pet sitter that your dog has Addison's, and plan ahead for stressful events with your vet's guidance. Watch for early signs that the dose needs adjusting, such as lethargy, a poor appetite or excessive thirst, and call your vet before they turn into a crisis.

This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.