Ktbalu, you are misreading my post. The two times my horse got Lyme, I was not using equispot. Ticks were free to climb on and bite my horse thereby infecting him. My wording was deductive reasoning for why I believe equispot to be effective.
Yes you can treat lyme with doxyclyine, but it's far better to prevent ticks from biting in the first place. It's a very expensive treatment, and the virus is very hard to completely kill. Once a horse has had it once, he is far more suspectible to recurrence.
You just have to see your distance...you don't have to like it.