Canine Hypoadrenocorticism Disease

Dog Addison's disease or Canine Hypoadrenocorticism is caused by a lower than normal production of hormones by the adrenal glands (a small gland located near the kidney that secretes several different substances such as salt, sugar and water that help regulate normal body functions) that results from the reduction in corticosteroid. Adrenal gland responsible for producing cortisones (glucocorticoids), hormones that helps your pet's body deal with stress, and mineral corticoids that regulate the quantity of potassium and sodium in the bloodstream. Addison's Disease can cause many serious health complications, and has a high probability of being mis-diagnosed as another disease. This is because the symptoms of Addison's disease in dogs are relatively general, including fatigue, diarrhea, sweating, and muscle pain. The most difficult aspect of dealing with Addison's disease in your dog is receiving a positive diagnosis for the disease.

Certain dog breeds are suspected to be more prone to develop Addison's disease. These breeds include Portuguese Water Dogs, Bearded Collies, Standard Poodles, Great Danes, and the Soft Coated Wheaten Terrier. Dogs that have had surgery near the pituitary gland or hypothalamus may also develop Addison's disease. It is not a common disease but when it does occur it is primarily in young or middle-aged female dogs averaging on 4-7 years of age although any age or gender may be affected. Usually, it is only the outer portion of the glands that are affected. There are two different classifications for Addison's disease, which depend largely on the underlying cause of the adrenal insufficiency. In primary Addison's disease, the adrenal insufficiency is directly caused by improper function or damage to the adrenal glands. In secondary Addison's disease, the adrenal insufficiency is not because of malfunctioning adrenal glands. Secondary Addison's disease is caused by the improper transmission of the hormone ACTH from the pituitary gland, or a reduced production of corticotrophin releasing factor (CRF) by the hypothalamus. In secondary Addison's disease, the adrenal gland is still functioning normally.

Common causes of dog Hypoadrenocorticism are: 1) Adrenal Dysgenesis is a rare genetic condition in which the adrenal gland has not formed properly during a dog's early development.; 2) Adrenal Destruction, the adrenal gland is progressively damaged by disease, and is subsequently unable to function.; 3) Impaired Steriodogenesis, the adrenal gland is unable to produce cortisol on a biochemical level.; 4) Damaged Pituitary Gland; 5) Prolong use of steroid hormones; and 6) Lack of Aldosterone that causes drop in blood pressure and severe dehydration. Genetic continuity between dogs and humans helps to explain the occurrence of Addison's disease in both species.

Blood drawn from dogs with Addison’s disease is deficient in cortisol. Sick dogs often show a pattern of changes in their white blood cells (WBCs) called a stress leukogram. This pattern of changes in the WBCs is caused by cortisol. The absence of a stress leukogram in a sick dog may be a clue to consider Addison’s disease. The urine is often dilute.

The standard treatment involves replacing the mineralocorticoids and glucocorticoids in the body. There are two stages of treatment for Addison’s disease; in-hospital treatment and long term treatment. Very sick dogs with Addison’s disease require intravenous fluids, cortisol-like drugs and drugs to neutralize the effects of potassium on the heart. Long-term treatment involves the administration of hormones in one of two forms; either a daily pill or a shot that is given about every 25 days. Because dogs with Addison’s disease cannot produce more cortisol in response to stress, stress should be minimized whenever possible. It may be necessary to increase the amount of hormones given during periods of stress (e.g. boarding, surgery, travel, etc.). Most of the medications used in the therapy of hypoadrenocorticism cause excessive thirst and urination. It is absolutely vital to provide fresh drinking water for the canine sufferer. A newer option in the treatment of Addison's disease is a drug called DOCP. The injection is long acting and only needs to be given once every 25 days. DOCP has been intensively tested and been shown to provide better electrolyte regulation than Florinef. Some animals on DOCP may also need to be placed on a low maintenance dose of prednisone.