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Understanding Addison’s Disease in Dogs 

Written by Anna Hollisey


terrier lying down
  • Addison’s Disease is a lifelong condition but with the correct medication, there's no reason a dog with this disease can't live a happy, long life 
  • A diagnosed dog has malfunctioning adrenal glands which are needed to produce the hormones cortisol and aldosterone 
  • Cortisol is needed to help your dog regulate stress and help them calm down 
  • Aldosterone helps regulate things like sodium, chloride and potassium
  • Whilst most dogs are diagnosed when they're young, it's often hard to diagnose as the symptoms can be wide ranging 

Addison’s Disease is a chronic condition affecting 1 in 200 dogs. It occurs when the adrenal glands stop producing essential hormones such as cortisol and aldosterone. While it’s difficult to spot, it is treatable and can usually be managed to give your dog a long and enjoyable life. 

Signs of Addison’s Disease

Addison’s Disease is frequently misdiagnosed in dogs – but it’s not your vet’s fault (or yours). It masquerades as gastroenteritis, kidney or heart problems, and that’s because symptoms can affect all those areas.

Around a third of cases are diagnosed when the dog has an ‘Addisonian crisis’. This means they’ve collapsed or gone into shock because their system became unable to cope with stress. At this point your vet will test for Addison’s Disease, but if you see any of the below symptoms, you could ask them to test sooner.

Look for these symptoms in your dog’s behavior and medical results:

  • Lethargy which comes and goes
  • Lack of appetite
  • Vomiting and diarrhea 
  • High level of enzymes in the kidneys
  • Low blood sugar
  • High potassium and low sodium levels

What Causes Addison’s Disease?

Addison’s Disease means that the dog has malfunctioning adrenal glands. These glands produce hormones, and two of the most important are cortisol and aldosterone (both steroids). 

Cortisol has some important jobs to do in your dog’s body. One is regulating stress – it’s normally produced in stressful situations to help your dog calm down. But it’s also responsible for regulating blood glucose, metabolism and blood pressure. If cortisol is not being produced, your dog can have an Addisonian crisis – triggered by intense stress – because they don’t have the hormone balance to cope. 

Aldosterone, meanwhile, is in charge of regulating levels of things like sodium, chloride and potassium. If it’s not working, there’s more pressure on your dog’s heart and kidneys – and in severe cases, either can fail. 

Why do the adrenal glands stop working? It is not entirely clear. Causes could be an autoimmune response (their immune system halts the glands) or a condition which damages the adrenal glands, like cancer or disease. 

If it’s going to affect your dog, you’ll probably find out when they are young (aged 2-6). But be careful – because Addison’s Disease is often misdiagnosed as something else. That’s because it produces a wide range of symptoms which tend to come and go. 

Which Dog Breeds are Prone to Addison’s Disease?

  • Poodles
  • Great Danes
  • Rottweilers
  • Terriers (Wheaten, West Highland or Airedale)
  • Some working dogs (Springer Spaniels, Bassett Hounds, Portuguese Water Dogs, Duck Tolling Retrievers, Bearded Collies)

How is Addison’s Disease Diagnosed?

If your dog’s had an ‘Addisonian crisis’ then the vet will likely treat the shock with intravenous steroids. If the dog responds to those then they may be under-producing steroids, which is a key indicator of Addison’s.

In any case, if your veterinarian has reason to suspect Addison’s, they will diagnose it through blood tests and another test called ACTH. In this test the vet checks your dog’s current level of cortisol in the blood. Then they administer ACTH, a hormone which produces cortisol during stress. After an hour another blood test will show whether your dog’s cortisol level has increased; if not, their adrenal glands didn’t produce any and the likely cause is Addison’s Disease.

How is Addison’s Disease Treated?

If your dog has had an Addisonian crisis, they’ll need hospitalization. Your vet will treat them with intravenous fluids and steroids. They’ll also prescribe an oral medication such as fludrocortisone to replace the corticoids that your dog’s body isn’t producing. There is an injectable alternative for dogs who don’t swallow tablets well. 

Afterwards, your vet will recommend a treatment plan to keep your dog safe and functioning. This means continuing with the medication (oral or injected – which doesn’t need to be delivered as frequently) and arranging regular blood tests to be sure that levels are balanced. 

Addisonian dogs can struggle to deal with stress. So if you are planning a trip away or a visit to the vet’s, you may need to take extra precautions. This could be increasing their medication (under guidance from the vet) or even adapting your lifestyle to help your dog stay calm.

Addison’s Disease is a lifelong condition (recovery has never been reported, according to this paper published in 2010 It’s treated through hormone replacement therapy and will be monitored during your dog’s life. Your vet will check hormone and electrolyte levels to establish the right dosage for day-to-day functioning. After that, you’ll probably need to arrange annual testing to ensure that your dog is taking the right amount of medication(s). 

Time for some good news: for most dogs who are diagnosed with Addison’s, the right medication works. Once you learn to manage the disease, your dog can lead a full and happy life. 

Can you Prevent Addison’s Disease?

Addison’s Disease is a condition with unknown causes and, for the most part, cannot be prevented. Primary hypoadrenocorticism is triggered when either the dog’s immune system shuts down the adrenal glands, or the glands are damaged in some other way. 

However, one type of Addison’s – Iatrogenic primary hypoadrenocorticism – has been known to be caused by certain drugs which can act on the adrenal gland. Some of these medications are prescribed to treat Cushing’s Disease (which is an overproduction of steroids). Ketoconazole, trilostane, or lysodren can shut down the adrenal gland and trigger an Addisonian crisis. 

Giving too much of, or suddenly stopping, any of your dog’s medications can be dangerous and should always be carefully avoided. Take care to follow the instructions from your vet and stick to exactly the right dosage – then remember to keep your dog’s medication in a place they can’t reach.