What is Addison’s disease?

Addison’s disease occurs when the adrenal glands (located adjacent to the kidneys) fails to produce enough of the hormone cortisol and, in some cases, aldosterone.  This can be as a result of damage to the outer layer of one or both of the adrenal glands. Cortisol ‘s primary job is to help the body deal with stress. The release of Cortisol from the adrenal glands is triggered and regulated by hormones produced by the pituitary gland, which is located in the brain.

The hormone aldosterone helps maintain blood pressure and the water and salt balance in the body, by helping the kidneys to retain sodium and excrete potassium.

What are the symptoms of Addison’s disease?

Addison’s disease can be difficult to diagnosis as symptoms can be quite subtle to begin with or they can be mistaken for the symptoms of other illnesses.  Look out for:-

• Fatigue
• Depression
• Loss of appetite

Your pet may also go on to show signs of:

• General muscle weakness
• Pain in hind quarters (may be first noticeable if your dog is reluctant to jump onto a sofa or bed that he is usually comfortable and happy to do)
• Shivering or tremors
• Vomiting diarrhoea

Symptoms can come and go despite the disease still being present and continuing to damage the adrenal glands. Symptoms may also appear to worsen when your pet is stressed.

What are the causes of Addison’s disease?

Addison’s disease can occur as a result of injury or disease, which has damaged the outer layer of the adrenal glands, affecting the glands’ ability to produce the hormones cortisol and aldosterone. Auto immune diseases, physical injury, adrenal tumours, ingestion of toxic drugs or chemicals and long term use of the drug mitotane to treat Cushing’s Disease, can each sufficiently damage the adrenal glands to cause Addison’s disease.

Long-term steroid therapy can cause the adrenal glands to become non-functioning, triggering the disease. Also, considering its role in the function of the adrenal glands, any damage or illness affecting the pituitary glands, can also be a cause of Addison’s disease.

What are the risk factors of Addison’s disease?

Addison’s disease is most commonly seen in female dogs between 4 and 6 years of age, although male and female dogs of any age can be affected.  It is believed that some breeds are more likely than others of developing the disease e.g. Standard Poodles and Bearded Collies.

Diagnosis

In the early stages, Addison’s disease is difficult to diagnose due to the mild symptoms, which can easily mistaken for other illnesses.  If your pet is showing symptoms take him to your vet to be checked over. After a thorough examination and a review of your pet’s medical history and symptoms, your vet is will take some simple blood tests. If the results lead your vet to suspect Addison’s disease (such as low sodium and high potassium levels) he/she is likely to want to take a more specific blood test, called an ACTH test, which measures the level of cortisol in the blood.  As cortisol levels very from hour to hour in a healthy animal, a number of samples will need to be taken, before and after your pet has been given an injection of a hormone (ACTH) to stimulate your dog’s adrenal glands. Once the samples have been analysed, the results will indicate whether the adrenal glands are functioning properly and confirm, either way, whether your pet has Addison’s disease.

What treatment can be Addison’s disease?

Sometimes, due to the often subtle and irregular symptoms, the illness may not be recognised for sometime. If your dog goes onto suffer an Addisonian crisis, he will suddenly become weak with vomiting and diarrhoea, and may even collapse.  In these circumstances, your pet will be hospitalised and put on IV fluids to get him hydrated. Once stabilised your dog will undergo a number of tests, which will help the vet prescribe and medicate your pet appropriately, before he can go home.

Any animal diagnosed with Addison’s disease will need to receive daily medication to provide them with the hormones the adrenal glands are no longer providing, the doses of which are adjusted to meet the need of each individual animal. Your dog should go on to lead a normal happy life as long as he gets regular check ups and blood tests to ensure he is being appropriately medicated.

How to prevent Addison’s disease

As the exact causes of Addison’s disease are unclear, prevention is difficult.  Avoiding injury to the abdominal area and weaning dogs off long-term steroid therapy can prevent some causes of the condition. The prognosis, however, is usually good, if the condition is caught early enough.