You should take your dog to the doctor b/c you said he got kicked by a horse he might have gotten internal injuries that you wouldn't know about except for the fact that he is peeing blood that is the only warning signs.
My Dog Is Peeing Blood After Getting Kicked By A Horse, What To Do?
Since your dog is urinating blood, it is HIGHLY likely his bladder or kidneys got damaged-a veterinarian can run tests, so get there ASAP! If your pup has internal bleeding, he could go into shock very easily, so keep him indoors (if you're in a cold environment), allow him to rest, provide plenty of water. Hope your dog is okay!
Take him to a vet, sounds like there is some internal bleeding.
This happened to my dog also