There is a mare named Annie at the barn I board and work at that is friends with another mare, Cammie. Annie and Cammie have been friends for a few years, and then one spring day I walked outside to see Annie 'winking' and backing into Cammie. At first, Cammie was annoyed and tried biting and kicking her away, but after a while Cammie eventually mounted her. When I took Cammie out and put her in another paddock and they went nuts. They kept neighing at each other from across the barn, and they paced the fence for a while until both of them calmed down. I've tried to keep them separated, they only act out when Annie is in heat not the other way around. But since I've kept Annie away from Cammie, whenever Annie is in heat she annoys other mares, and has gotten two other mares to mount her. One of the mares has even had three foals. You'd think she'd know the difference. Lol I was wondering if anyone else has had this problem before or has heard of it? Is it a hormone imbalance?