Cushing's Syndrome
Cushing's syndrome (also called hypercortisolism or hyperadrenocorticism) is an endocrine disorder caused by high levels of cortisol in the blood. Cortisol is released from the adrenal gland in response to ACTH being released from the pituitary gland. High levels of cortisol can also be induced by the administration of drugs. Cushings disease, or more properly termed secondary hyperadrenocorticism, is very similar to Cushing's syndrome in that all physiologic manifestations of the conditions are the same. Both are characterized by elevated levels of cortisol in the blood, but the cause of elevated cortisol differs between the two. Cushing's disease specifically refers to a tumor in the pituitary gland that stimulates excessive release of cortisol from the adrenal gland by releasing large amounts of ACTH. It was discovered by American physician, surgeon and endocrinologist Harvey Cushing (1869-1939) and reported by him in 1932.
Cushing's syndrome--which is also a relatively common condition in domestic dogs and horses--is almost invariably caused by pituitary neoplasia, characterised by abnormal fat deposition. (The syndrome in horses leads to weight loss, polyuria and polydipsia and may cause laminitis.)