Addison’s disease in dogs

Isolated dog


  • Addison’s disease is a rare condition that develops when the body’s natural steroid levels drop dangerously low.
  • Natural steroids are normally produced by the adrenal glands, and Addison’s develops if the glands stop working.
  • Symptoms of Addison’s are often vague, making it tricky to diagnose.
  • Treatment for Addison’s involves replacing the missing steroids and with treatment, outlook is very good. Left untreated, Addison’s is often fatal.
  • Addison’s is more common in female dogs and usually develops at around 4-6 years old.

General information

Cells all around your dog’s body rely on natural steroids produced by the adrenal glands; they are essential for life. Addison’s disease (hypoadrenocorticism) is a rare condition that develops when the adrenal glands stop working properly and levels of natural steroid drop dangerously low. In most cases, Addison’s disease is caused by a fault in the immune system that causes it to attack and damage the adrenal glands.

Addison’s usually develops slowly and causes a wide range of vague symptoms that can be difficult to spot. As a result, it’s a condition that often goes unnoticed until severe symptoms develop. However, in some cases, Addison’s develops rapidly and causes very sudden, life threatening illness.

Dogs with Addison’s disease lack two main steroids: ‘cortisol’ and ‘aldosterone’.

  • Cortisol. Cortisol is important for the body when dealing with stress and dogs with Addison’s disease often show more symptoms at times of stress.
  • Aldosterone. Aldosterone helps regulate blood pressure and water levels in the body; dogs with Addison’s often develop low blood pressure and become dehydrated.

Addison’s is most common in female dogs and often develops at around 4-6 years old. Any breed of dog can develop Addison’s but the condition is more common in certain pedigree breeds such as the standard Poodle, West Highland White Terrier, Great Dane and St Bernard.

Addison’s disease is the opposite of Cushing’s disease (hyperadrenocorticism), a condition that develops when the adrenal glands produce too much steroid.

Illustration showing the adrenal glands in a dog

The adrenal glands sit in front of the kidneys and produce steroids. Click to enlarge.


Symptoms of Addison’s are often vague and include:

Some dogs with Addison’s don’t show symptoms until they are severely affected, at which point they go into an ‘Addisonian crisis’. Symptoms of an ‘Addisonian crisis’ include:

When to contact your vet

Contact your vet if you have noticed symptoms of Addison’ disease. Contact your vet immediately if you suspect an Addisonian crisis - it’s an emergency, never wait to see if they improve. You know your dog, if they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.


Often the symptoms of Addison’s are vague, which can make it tricky to diagnose. If your vet suspects Addison’s they are likely to need a range of blood and urine tests and perhaps an ECG to confirm.


Addisonian crisis. If your dog has collapsed with sudden symptoms of Addison’s disease, they will need lifesaving, emergency treatment. This is likely to include a fluid drip, steroids directly into a vein and various other medications to stabilise their condition. Once they are stable, treatment to control their Addison’s can begin.

Standard treatment. Treatment for Addison’s disease requires regular medication for the rest of your dog’s life. Most dog’s need two types of medication to control Addison’s disease:

  1. A monthly injection, given by your vet (to replace aldosterone).
  2. Daily tablets, given at home (to replace cortisol).

If treatment is stopped, symptoms will return so it’s important to follow your vet’s advice and give all medication as directed. Watch our video below for guidance on how to give your dog a tablet.

Monitoring. It is important to monitor your dog for any new symptoms and make sure you attend all their check-up appointments, they will receive a health check at each appointment and your vet will perform repeat blood tests from time to time.

Avoiding stress. Try to avoid stressful situations for your dog; their lack of cortisol means that stress is likely to make them unwell. Your vet may advise a higher dose of medication at times of stress e.g. fireworks night or a house move. Never adjust your dog’s medication without speaking to your vet first.

How to give your dog a tablet


Once a successful treatment regime has started, the outlook for most dogs with Addison’s is very good. A dog with well-controlled Addison’s is likely to live a relatively normal life.


Addison’s is a condition that requires lifelong treatment and regular check-ups. For this reason, treatment for a dog with Addison’s can become very expensive. It’s important to speak openly to your vet about your finances, the cost of treatment, as well as what you think is right for your dog.

Consider insuring your dog as soon as you get them, before any signs of illness start. This will ensure you have all the support you need to care for them.

Published: September 2019

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Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst