Addisons disease or Hypoadrenocorticism results from an insufficiency of adrenal hormones (cortisol and aldosterone) which are functional in many processes in the body (fat metabolism, stress response, sugar, salt and water levels, inflammatory processes…..). The adrenals are triangular shaped glands which sit above the kidneys and form part of the endocrine system. They are composed of two parts, the inner medulla and the outer cortex. It is the outer cortex which is destroyed in hypoadrenocorticism.
Once 80% of the adrenal cortex has been destroyed, cortisol and aldosterone are not released in sufficient amounts and fat metabolism, the stress response and the regulation of sugar, salt and water levels are disrupted. Eventually the dog goes into what is known as an Addissonian crisis because the dog is unable to regulate it’s bodily functions. Diarrohea, vomiting, weight loss and lethargy are the most common symptoms of hypoadrenocorticism but they may present over a long period of time with periods of good health in between.
Over time the dog becomes very ill and many vets are slow to diagnose the condition as it is not commonly seen and mimics many other conditions. In view of this the dog often suffers for a significant time and many dogs are known to die before the condition is diagnosed or are too ill at diagnosis for treatment to be effective. Providing the diagnosis is made quickly, dogs can live normal, happy lives although they are on medication for life.
Hypoadrenocorticism is a poorly understood condition that is believed to be an autoimmune disease with genetic factors which contribute to the risk of the disease. Some genes have already been associated with Hypoadrenocorticism in Portuguese Water dogs. It has also shown that the disease is highly inheritable in this breed. The Great Dane is one of the breeds that have a reported high incidence of Hypoadrenocorticism (Rottweiler, West Highland White Terrier, Standard Poodle, Wheaton Terrier and Bearded Collie being others)
Hypoadrencorticism is diagnosed by a veterinarian via a series of blood test, which show low sodium and high potassium levels and high levels of kidney enzymes. The definitive test for Hypoadrenocorticism is an ACTH stimulation test which takes around 2 hours to complete. Most dogs are diagnosed with the disease between 4 and 7 years of age.