Situated close to the kidneys are the adrenal glands Thomas Addison, a medical doctor wrote about problems with adrenal glands in 1855. He gave his name to the underactivity of the adrenal cortex otherwise known as Hypoadrenocortisism. The adrenal glands are bean shaped creamy pink organs. Although small they have critically important functions. The outer layer of the gland is known as the cortex and this produces two very important hormones. Cortisol, which one needs to deal with all sorts of stress and Aldosterone which acts on the kidney to regulate the amount of salt in the body.
Cortisol also decreases inflammation, increases blood sugar and suppresses the immune system. The hormone also influences the lymphocyte production which are also involved in immunity. During times of stress, both physical and mental, more cortisol is released.
Aldosterone , the other hormone has complex reactions to maintain the serum levels of sodium and potassium. The blood levels are tightly controlled and if this mechanism fails the dog rapidly becomes very ill
The inner part of the adrenal gland is called the medulla. This produces the hormone Epinephrine which you may know by its old name of Adrenaline. Addison’s disease does not affect the medulla in any way.
The cause of the reduction of activity of the adrenal cortex is nearly always due to the auto destruction of the hormone producing cells in the cortex. The immune system mistakenly identifies these cells as foreign , should not be there, and sets out to destroy them. There are other mechanisms for Addison’s disease but in Beardies the problem is virtually always autoimmune.
One problem is that Vets see so few acute cases of Addison’s disease that it is very often not immediately recognised. Blood testing will suggest major chemical in- balances as seen in some forms of renal failure. Unless someone thinks of Addison’s disease it will be too late and the dog will die. They will urgently need treatment with steroids. If the condition is recognised and the hormone defects corrected properly the dog can continue a normal life on replacement medication. If you suddenly have an acutely ill dog for no apparent reason always ask your Vet to consider Addison’s disease
You will recall that Haplotype 3 in the DLA has been shown to be a possible predisposition to the condition in the presence of an environmental trigger and the susceptible combinations of about 40 other genes. It occurs slightly more commonly in bitches and the average age of onset is usually aged about 5 and a half. This causes breeders a dilemma as they are likely to have already been bred from before becoming affected. Once the condition is diagnosed clearly the Beardie should not be used further in a breeding programme. Responsible breeders should have no hesitation in informing any puppy owners that their dam has been affected. A careful discussion about the puppies use for breeding needs to take place especially with the potential stud dog owner to ensure no history of the disease in immediate ancestors. Testing for Haplotypes is still quite costly but this may be a future indication to ensure any mating planned does not increase the risk of doubling up on a haplotype and generating homozygous off spring.
It goes without saying that if a stud dog should develop Addison’s disease He should be withdrawn from stud immediately
Addison’s disease is a chronic condition but it may present acutely with a sudden collapse. The first symptoms are vague and come and go and may well be attributed to something else, like over exercise, a stomach bug, or indigestion. Early signs may include listlessness, weakness, vomiting, diarrhoea or intermittent loss of appetite. Often the dog is treated symptomatically by the vet with drugs to counter diarrhoea, or vomiting , offering bland diets or drugs like metrinidazole
Over time it may become clear that these episodes occur shortly after stress, such as a family party, guests in the home, rowdy children, seasons or a spell in a boarding kennel or any other change in routine. Eventually the time comes when the poor dog is suddenly quite ill and presents to a vet in crisis. Blood sample are taken and hopefully the astute vet and owner will make a diagnosis. Having reached the crisis point the dog will die of circulatory collapse very quickly. The pattern of tests results may include a high serum potassium, low serum sodium, low urine specific gravity and high level of blood urea and creatinine. Blood gases may show a metabolic acidosis. The only definite proof of the diagnosis is for the vet to do an ACTH stimulation test. If the adrenal glands are working normally the ACTH injection will cause a rise in the blood cortisol level in the next hour. If however the adrenal gland is damaged it will not respond by producing a rise in plasma cortisol and Addison’s disease is proven.