Stopping female horse estrus

Answer 1

Once a mare is in estrus she has to be allowed to go out before methods can be employed to avoid any additional heat cycles.

Anestrus can be maintained through the use of progesterone in oil injected IM or through the use of progesterone products on a daily basis. Ideally, these products are used to prevent mares from cycling into heat during an important

event where estrus would detract from the mare's performance, and then discontinued once the event ends.

These products, if used continously for a prolonged period can result in intrauterine infection.

Another method involves depositing a sterile sphere into the mare's uterus, which "fools" the mare's reproductive system into a false pregnancy. The use of this method has some advantages over the progesterone