Addison's disease is a condition characterized by adrenal insufficiency. This means that the adrenals are not producing sufficient cortisol for normal body functions.Though slightly difficult to diagnose due to many generalized symptoms, the causes of Addison's disease are usually related to the adrenal gland (and sometimes, the pituitary gland). Both of these glands are responsible for producing certain types of important hormones. In order for your dog's body to function properly, it is required that a proper balance of hormones is present at all times. Here are some of the most common documented causes of Addison's disease and adrenal insufficiency.
Adrenal Dysgenesis is a rare genetic condition in which the adrenal gland has not formed properly during a dog's early development. This is extremely rare, and is only identifiable by examining the adrenal gland itself. Also, Adrenal Dysgenesis usually affects a dog immediately after birth, and will cause immediate and possibly serious health complications.
In this condition, the adrenal gland is unable to produce cortisol on a biochemical level. In order to produce cortisol, cholesterol is required by the adrenal gland. The cholesterol is then converted into steroid hormones. There are certain medical conditions that can interrupt the proper delivery of cholesterol to the adrenal glands, which in turn will prevent the proper production of cortisol.
In Adrenal Destruction, the adrenal gland is progressively damaged by disease, and is subsequently unable to function. The most common cause of Adrenal Destruction is a situation in which the dog's immune system mistakenly attacks the adrenal glands. This is called an autoimmune attack, and can cause serious damage to the outer layer of the adrenal glands.
If your dog has been prescribed any type of steroid therapy medication for a prolonged period of time, this can actually bring about Addison's disease. This is because prolonged frequent use of steroid hormones can cause progressive damage to the adrenal glands, most commonly seen by use of the steroid hormone prednisone.
In rare cases, Addison's disease, and the subsequent adrenal insufficiency, can be caused by an improperly
functioning pituitary gland. The pituitary gland is responsible for producing certain hormones that affect
hormone production in the rest of the body. The hormone produced by the pituitary gland that directly affects
the production of cortisol by the adrenal gland is called ACTH. If the pituitary gland is not producing enough
ACTH, the adrenal gland will not produce cortisol, resulting in the condition known as Addison's disease.
The pituitary gland can be improperly functioning if it has any damage or obstruction to normal operation. This can be caused by tumors in the pituitary gland, exposure to severe radiation, infection of the pituitary gland, or damage to the pituitary gland during surgery. Surgery-induced damage to the pituitary gland is most commonly seen in procedures to remove the hypothalamus, which is a procedure rarely done on dogs.
The adrenal glands are also responsible for producing a hormone called Aldosterone. Aldosterone helps to regulate blood pressure, and allows the kidneys to maintain a proper water vs. salt balance in the body (by helping the kidneys retain sodium and excrete potassium). If the adrenal glands are not functioning properly, and the production level of Aldosterone drops, this can cause a drop in blood pressure and severe dehydration. Mis-functioning adrenal glands are the main cause of Addison's disease.