I was going to say this. Put your horse on the offensive. A few years ago I read about a trail leader at a dude ranch near Yellowstone who managed to get her horse to turn & charge a grizzly bear that attacked their group. (It was a giant Percheron gelding that none of them heretofore had wanted to ride) . The product that @Garythesquirrel has looks promising.
Honesty? I’m a redneck at heart & have no qualms about bringing Messieurs Smith & Wesson along for the ride. They’d be my absolute last resort. But even as a dog owner & lover, I’m so damn tired of people not training their dogs. I’ve shot at dogs coming onto my property & killing my poultry. I’ll protect my horse if i have to.