It is absolutely astounding the number and types of problems that can result from a sore mouth or dental problem including head shaking, hanging on the bit, backing haphazardly, rearing, kicking, refusing to move, throwing themselves to the ground, shortened gaits, crooked gaits, sore shoulders, sore backs, sore hocks, it goes on and on and on.......get your horse's teeth checked and tended to BEFORE bridling in the first place and at least annually ever after. Sometimes you might not even realize the problem stems from the teeth but I always advise with ANY difficulty get the teeth checked first and quite often that IS the problem.