Lisa Brownlee, DVM, DACVIM

Naturally occurring hyperadrenocorticism (HAC) is an endocrine disorder resulting from the excess production of cortisol or other adrenal hormones by the adrenal cortex. The clinical syndrome was first documented in people by Dr. Harvey Cushing in 1932 and is also known as Cushing's syndrome.

There are several manifestations of adrenal disease in cats, ranging from hypoadrenocorticsm to several forms of hyperadrenal activity. All are considered relatively rare, but it is possible that we may discover some more frequently if we have a higher index of suspicion.

Normal neural stimulation of the hypothalamus produces corticotropin-releasing hormone (CRH). Corticotropin-releasing hormone stimulates the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary. ACTH exerts its effects on the adrenal cortex and stimulates the zona fasiculata to release cortisol, the zona reticularis to release androgens and the zona glomerulosa to release mineralocorticoids, but the primary effect of ACTH is on cortisol release.

Hyperthyroidism is the most common endocrine disorder in cats. This disorder has been noted with increased frequency since the late 1970's. It also appears to be more prevalent in certain geographic locations.