Ever notice that your horse exhibits behaviors that were unusual (or maybe you didn't think they were unusual) that made him look like he was either in pain somewhere, or maybe he looks just plain grumpy.
Does your horse resist being saddled, does he pin his ears when you rub your hands along his back or try to step away? Does he carry his head crooked? Maybe he doesn't want to bring his hind end under himself when he works any more.
Read more: Got a stiff back - well chiropractors are for horses too [click]