Im not too sure that it would help, my old girlfriend used to ride horseback and would say the same thing. While on horseback she could often get within 5-10 feet of the deer. I think the deer know that the horse is not a threat, and assume that it is just another wild animal. I asked her to try sometihng one afternoon for me. THere were three doe out in the field where she rides and i had her ride over to them, they didnt mind her or the horses company at all. She came back and i told her to go back and and walk on the ground next to the horse. She only made it 50 yards from the deer until they bolted. I think they know a human when they see one.