I had the same problem with one of my horses. He scratched part of his mane & tail out and would lie on the ground over a tree root to scratch his stomach. I have had a great deal of success with SmartPak APF. It comes in a biscuit form & we drop it in his feed. Not only does he eat it first but if we burry it in his feed he will root around until he finds it & still eat it first. We have another horse on it as well due to runny allergy eyes which prompted her to scratch her face & on occasion make one or more of her eyes swell. We love this stuff & it works like a dream!