In addition, some anovulatory follicles begin to produce progesterone that takes the mare out of heat. This can be successfully treated with prostaglandins. Although Cushing's disease is not a reproductive disease, it does affect the adrenal gland, which indirectly affects reproduction, causing the mares not to cycle. The disease typically is a problem in horses more than 15 years of age. Besides anestrus, there are varied clinical signs that might be present.
Treatment is geared primarily to addressing symptoms.
Occasionally, they won't cycle the first year at the farm. No hard and fast rules here, and many practitioners have their own 'let-down' programs that they have success with. Although much is known about the reasons and remedies for anestrus, researchers are actively involved in further examining the condition. Domperidone looks promising. Acupuncture has reportedly been effective in other species, but no work to date has been done in this area in horses.