Thanks guys. Do you think he finally just snapped and fought back? They said the mare slipped and fell and he went and started biting her after she kicked him. My moms horse is usually turned out with him and protects him from this horse, but she had to get moved to a different pasture, and they said all of a sudden the horses started running around and by the time they went to see what was going on my horse was chasing the said horse and biting at her butt, than she kicked him in the face and than she slipped and he went after her... of course this is what everyone is saying. I mean he has been going out for like two years and he has NEVER layed an ear back at any horses. He eats by himself, and always runs the other way when he is confronted.