I was just having a huge battle with ticks. I have a gelding a got last fall after tick season and found out he had never been exposed to ticks before and he's 13. He had a bad reaction, swelled up and was oozing where he was bit. It was to the point the whole underside of his jaw had crusties on it. We have now made big progress and its on its way to healing nicely. Just bald patches from the crusties forming and him rubbing from being itchy. I figure it was his body's natural response to not let them into the skin as they would bite, crust would form and the tick would be suffocated in the crusties.
I used a spray that was a mix of regular blue dawn dish soap/vinegar/fresh fine chopped garlic and sprayed it on his body to prevent them. We washed the affected areas with hibatane, applied blue lotion and then swat on top. The swat killed the ticks on contact so really helped preventing them from getting into those areas. I have noticed a HUGE decrease in the ticks on him. They mostly now are just in his tail and I pick those out when even Im out.
I've also tried to get red lake diatomaceous earth powder but had no luck. I've heard that putting it in a sock and dusting the horse liberally really helps prevent ticks and kills them. I've tried to get spot on treatments but no one here carries them and a friend said it barely worked here (the ticks we have are like super breed ticks lol)
Theres lots of other suggestions too in the thread I had started. Some said mowing the pasture although in my case we can't.. its 160 acres of untouched pasture. Trying to mow it would be impossible and doing a burn would end up with very bad results and create a huge danger, would most likely result in a huge forest fire. Treatments To Prevent Ticks