I've got the same problem. Literally nothing is working. He is getting bald right now. I have the special rug mentioned below but it hasn't helped much either. He even scratches his head with his hind feet
Yes! My vet told me that my horse has the worst bug allergy they have ever seen. In a horse he has to wear fly boots, a fly mask and a fly blanket.
He also gets meds, it's a powder that gets put into his AM and PM grain. I'll comment what his meds are in alittle bit