Adrenal gland disease is, unfortunately, a common disease of pet ferrets in the United States. Most affected ferrets are older than 2 years. While the exact cause of this condition has not been determined, it is believed that spaying and neutering ferrets at an early age plays a role. This is problematic because failing to spay females can result in life-threatening illness, while neutering males reduces odor and aggression. Removal of the testes or ovaries removes hormonal influences that appear to affect the adrenal gland. In the absence of these influences, the adrenal glands may overproduce several sex hormones, causing a variety of clinical signs. In some cases, the overactive gland can eventually become cancerous. Genetics may also play a role in the development of adrenal gland disease.