IS this lice?
A friends horses. Patchy hair, flaky stuff underneath. I haven't seen anything actually crawling around but...?
By the way, it is NOT bathing season here yet. Would you wait to treat, because, at this point saddle pads & tack cannot be hosed off without freezing. Or dust the horses now, dose with Ivermec and bathe when they can be bathed? I have no experience with lice in horses (goats, yes) so...