It's totally going to depend on the horse, but I know when I'm hiking and I come across them, I usually move off the trail and stop while they pass.

I have some friends and family that are horse people and I know enough that I know I don't want to be on the receiving end of one of their kicks.

In related news, I spooked a goat today while riding. I hit a bump and my bike made a loud creaking sound. The goat must have jumped a foot strait into the air. Poor little guy.