Has anyone used the natural apple cider vinegar formula I just read that if you give your horse 1 tablespoon a day in the water or on their grain it keeps the flies off from bothering them?

It sounds good enough. I use Garlic Pills I buy from a fishing store when I am going on a camping trip and I am always the one with no mosquito bites! Of course everyone cleans out my bottle by the time we are done. But it takes a day or two to get into your system.

Should be something similar the horses could take? And I might give this a go. If I can get back some feedback.