Cushing’s disease, or hyperadrenocorticism, is caused by excessive steroid hormones in the dog’s body. It mostly attacks older dogs and is commonly seen in terriers, dachshunds, poodles, German shepherds and golden retrievers.
Cushing’s syndrome in dogs includes three types of conditions:
- Adrenal-dependent hyperadrenocorticism – This is mainly the formation of a tumor in the adrenal cortex. The adrenal glands are responsible for the production of steroid hormones. The tumor causes an increase in the production of hormones, leading to symptoms related to Cushing’s. A tumor usually occurs in one of the two adrenal glands.
- Pituitary dependent hyperadrenocorticism OR Cushing’s disease – This is the formation of small tumors in the pituitary gland which is responsible for stimulating the adrenal glands through its own hormones. Pituitary-dependent hyperadrenocorticism causes both the adrenal glands to enlarge.
- Drug-induced hyperadrenocorticism – Exogenous steroids administered to treat canine skin disorders cause levels to increase. This signals the adrenal glands to inhibit production, which leads to shrinkage of the glands.
Surgical excision of the affected adrenal gland is used to treat adrenal-dependent hyperadrenocorticism. Supplements for dogs, which contain exogenous hormones, are used to restore levels until the time the shrunken gland returns to its original size.
Cushing’s disease is treated by specific Cushing’s disease medicine for dogs, a variety of oral drugs that have various influences of the adrenals to restrict production of hormones. Some of these drugs destroy the particular zona of the adrenal cortex that produces cortisol, while others inhibit enzymes associated with the production.
Prognosis of Cushing’s syndrome in dogs depends largely on the type of Cushing’s. Surgical excision of adrenal tumors usually resolves the condition. However, more than fifty percent of adrenal tumors are malignant and are found to have already metastasized at the time of detection. This has an adverse affect on the overall prognosis of the condition.
Pituitary-dependent canine Cushing’s presents a better prognosis in the short term. Pituitary tumors are normally very small in size and generally do not cause any major problem. In the long run, however, the condition increases the susceptibility to urinary tract infections, kidney disease, diabetes, high blood pressure and pancreatitis, which complicates matters further.
Iatrogenic or drug-induced hyperadrenocorticism has a relatively good prognosis, but only if schedules for withdrawal of drugs is properly adhered to.