Addison’s disease is rare but potentially fatal for dogs. All you need to know about Addison’s disease is in this article by Paul Manktelow BVMS MSc MRCVS.
The symptoms of Addison’s disease include increased thirst and urination, anorexia, lethargy, vomiting and dehydration. It’s important to seek veterinary attention immediately to treat this serious disease. It is deadly!
The correct medical term for this disease is Hypoadrenocorticism. It is caused by a lowered hormone production from the adrenal glands. These are small glands located near the kidneys.
The centre of the adrenal gland is called the medulla and the outer portion of the gland is called the cortex. Whilst both parts of the gland produce hormones, Addison’s disease concerns the outer cortex. This part of the adrenal gland produces the corticosteroids.
Amongst these are two very important hormones:
- Cortisol (also known as cortisone) – a glucocorticoid
- Aldosterone – a mineralocorticoid
One of the most important functions of the mineralocorticoids is to maintain blood pressure and maintain water balance. The glucocorticoids are responsible for metabolism and enabling the animal to deal with physiological stress. The functions of these hormones are extremely complex but any absence or lowered production of them can result in physiological disaster.
- Rare disease in dogs
- Incredibly rare in cats
- In dogs approximately 70% of cases are female
- Higher incidence in seen in un-neutered female dogs.
- Commonly in younger to middle aged dogs. Average age is 4 years
- May be hereditary in Standard Poodles and Bearded Collies
- Seen in Rottweilers and West Highland White terriers
The causes of primary Addison’s are not entirely clear. It is thought that the most common cause is an auto-immune destruction of the adrenal gland. This means that the body’s own immune system attacks the adrenal gland and destroys it.
Occasionally Addison’s can result from treatment of the opposite disease, Cushing’s disease (Hyperadrenocorticsm). Drugs used to reduce hormone production in an over active adrenal gland in Cushing’s disease can exceed their function and cause Addison’s. A dog that has been on long term cortisone can also develop Addison’s if this treatment is abruptly stopped.
Other less common causes of Addison’s are direct injury or removal of the adrenal gland. Secondary Addison’s results from the brains action on the adrenal gland but is thought to be much less common.
Addison’s disease has been described as “The Great Imitator” as it often presents with very vague and non specific signs which resemble illness in other parts of the body. For example, kidney or gastric disease
- increased thirst and urination
- lethargy / depression
- weight loss
and more seriously:
- slowed heart rate
- abdominal pain
When occurring in its acute form it is known as an Addisonion crisis and emergency veterinary treatment is a priority. There will be a huge drop in the dog’s blood pressure with extreme signs of shock. This fluid and electrolyte balance needs to be corrected immediately to avoid life threatening consequences.
The test most commonly used to diagnose Addison’s is called the ACTH stimulation test and this involves injecting a hormone and taking serial blood samples to be sent for laboratory analysis. The dog will often have to be hospitalised for the day.
Emergency treatment for Addisonion crisis involves stabilising the animal with intravenous fluids and correcting any electrolyte imbalances. It may also require giving intravenous steroids. Once the animal is stable then long term treatment involves replacing the missing hormones. Two drugs used to treat Addison’s disease are:
- Fludrocortisone acetate
- Desoxycorticosterone pivalate (not available in UK)
In the UK Fludrocortisone acetate is used which has both mineralocorticoid and glucocorticoid activity. This is given in tablet form daily. Initially salt may also need to be added to the food to stabilise the animal.
Long term monitoring may be required in the form of blood tests to measure the control of the disease. These blood tests are specifically concerned with monitoring electrolytes e.g. sodium and potassium. It may also be a wise precaution to keep some steroid tablets e.g. prednisolone for times of increased stress.
Generally dogs who are on treatment for Addison’s do extremely well. There is little indication to change diet or activity levels so dogs can go on to lead normal happy lives.
PS. We have borrowed this image from http://www.peterdobias.com/blogs/blog/14755341-addison-s-disease-natural-treatment-prevention. They have written a great article about the disease, so click on the site for info. We all want to help advise pet owners about this disease and hope you don’t mind us using your image to help promote advice. (If you do let us know)
All information is written and verified by veterinary surgeons and animal health professionals.