Addison's disease (hypoadrenocorticism) in dogs

Content by Dr Siân Burwood MA VetMB MRCVS

Addison’s disease in dogs is when the adrenal glands near the kidneys don’t produce essential hormones: aldosterone (which controls electrolyte levels) and cortisol (the ‘stress’ hormone’).

These hormones have important roles all over the body. Not producing them can lead to issues with blood pressure, gut function and metabolism.

Technically called ‘hypoadrenocorticism’, this disease can be difficult to diagnose as it looks like many other conditions, and can sometimes suddenly appear as an emergency ‘Addisonian crisis’. While lifelong treatment is needed, once under control, dogs can live full and relatively normal lives with the condition.

• Addison’s disease is the failure of the adrenal glands to produce certain types of hormones
• These hormones have effects all over the body, so lack of them can cause a wide range of vague symptoms
• Most dogs show waxing and waning episodes of vomiting, diarrhoea and lethargy, but some can present collapsed in an ‘Addisonian crisis’
• Treatment is lifelong, but manageable with monthly injections and daily tablets
• Most dogs and owners cope really well with a diagnosis of Addison’s disease and live full lives together

The adrenal glands sit next to the kidneys and produce many types of hormones – chemical messengers that tell other parts of the body what to do. Addison’s disease occurs when the adrenal glands no longer produce these hormones, either because of suspected auto-immune disease, or because some other disease (such as cancer) or drugs (such as those used to treat Cushing’s disease) block the gland working normally.

In some very rare cases, if the brain doesn’t produce enough of the hormone that tells the adrenals what to do, this can also cause symptoms.

Most cases of Addison’s disease cause a deficiency of the hormones aldosterone and cortisol. But in ‘atypical Addison’s’, only cortisol is affected.

Addison’s disease is usually first diagnosed in young to middle-aged dogs, with more females affected than males. While any dog can be affected, the disease is seen more frequently in:

• Poodles and Poodle crossbreeds (eg Cockapoos and Cavapoos)
• West Highland White Terriers
• Bearded Collies
• Great Danes

Addison’s disease is often referred to as ‘the great pretender’ as it can look like many other diseases – something that can be very frustrating for owners and vets. This is because the hormones involved affect so many body systems. The symptoms are often brought on by stress, and recognising this pattern can be key to tying the waxing and waning episodes together.

Mild symptoms include:

• Loss of appetite
• Weight loss
• Vomiting and diarrhoea
• Lethargy
• Increased thirst and urination

Sometimes dogs develop a very serious rapid presentation of the disease called an Addisonian crisis. These dogs may have:

• Collapse related to low blood pressure and slow heart rate
• Low blood sugar
• Kidney failure
• Severe vomiting and diarrhoea, sometimes with blood

Diagnosis

Diagnosis of Addison’s disease requires your vet to take blood tests alongside a thorough examination and history. Typical in-house blood tests will not fully diagnose the condition, but can give important clues – such as stress-related changes in white blood cells, or changes in electrolyte levels. They can also tell your vet how serious the condition might be, by looking at kidney function, hydration and glucose levels.

To officially diagnose Addison’s disease, your vet will need to do an ‘ACTH stimulation test’, where two samples are taken an hour apart to see if the adrenal glands show any response. With most veterinary practices, these samples will need to be sent to an external laboratory, and treatment may need to start before the results are back.

In the short term, Addison’s disease is treated by stabilising the patient first. This often requires hospitalisation for fluids and supportive care for sickness and nutrition. How long this takes depends on how sick the dog is when they present.

The hormones that are missing need replacing, and these are long-term treatments. Aldosterone is given as an injection, typically monthly for the rest of the dog’s life. Cortisol is given as steroid tablets that can be given at home.

Prognosis

The long-term prognosis for Addison’s disease is excellent (if no other diseases are present). And while regular vet visits and medications are needed, most dogs and owners cope with this really well. An Addisonian crisis is rare (especially for a dog on treatment), and rapid veterinary intervention is usually successful in this emergency case.

“Addison’s disease is something at the back of every vet’s mind when you see cases coming back again and again with vomiting and diarrhoea, and especially in anxious young adult dogs.

“Diagnosing it is rare, but I can recall a couple of patients in each practice I’ve worked in where you see them monthly for their injections. While it can sound very scary, treatment is very manageable for both dogs and owners – and each of those patients I can think of went on to live full and happy lives for many years afterwards”.

Dr Siân Burwood MA VetMB MRCVS

When you get a quote for Petgevity Lifetime Plus dog insurance, tell us about your dog’s Addison’s, plus any other conditions they’ve had in the past two years*.

It’s crucial to list your dog’s conditions when taking out pet insurance. This increases your chances of making a successful claim.  

Find out more about our dog insurance for pre-existing medical conditions.