Be careful with the little dogs. I've had 2 that would stand very quiet and act like they weren't bothered and then aim a killing stomp with a front hoof at a dog snarfing down some grain in a pan or some horse doo. Very much calculated on the horses part. Close as I've ever seen a horse tell a lie.
Had 2 others that would actively attack stray dogs or coyotes but not bother my dogs.
Most of the others would just kick an annoying dog. Couldn't care less unless the dog gets under their feet or sniffing at heels.