Lakota's normally fine with just one other horse in the ring with him. And if there's 2 other horses, he's usually fine except trying to go faster when they pass us. But out in the field, he'll challenge other horses over the fence. He's struck out at a few when we were trail riding and he's struke out at my friend's was taking her horse for a trail ride.
Now he's pinning his ears at every horse that goes past us in the ring. He'll stop, raise his head up, and pin his ears back. I want to show him next year but I can't take him to a show if he's going to get aggressive everytime another horse goes past him. Is there a way I can stop this? Thanks!