slewelf, thanks for mentioning allergy tests. A vet has to administer them, and they’re not cheap or 100% reliable, but they will help narrow down the field. Our first summer together, Boo, my Morgan mare, got fly bites on her front legs and her face, and when she got hives, I called the vet. She gave me a medicated shampoo and verified she had a fungus along with her allergies that was making her hair fall out. It was 104 most of last summer and I was out there three times a day to apply fly spray, make sure Boo’s fly sheet was still attached, and to feed her some of whatever the vet had given her in pill form. By the end of the summer she was hive-free and had stopped losing hair. I, however, was exhausted. I moved her to a boarding stable, and this spring my vet and I did a lot of preliminary work BEFORE fly season started. That’s when I had the allergy tests done, and so far Boo’s doing well. (She is allergic to one specific kind of night-feeding gnat, and trees and shrubs that are part of our SoCal landscape.) Horses that are allergic to fly bites, in particular, is such a huge problem all over the country that the people who put out the digital version of THE HORSE magazine put together a video of two vets, one an equine dermatologist, discussing how they treated itchy horses. They were unanimous that stabilized flax seed would work in nearly all cases. For horses that really rub themselves raw, an allergy test done by an equine dermatologist is the gold standard, although it’s very expensive. To me, this is a last resort. Good luck to all of us with our itchy horses this summer!