A horse that constantly gapes his mouth or chomps on the bit has one of a few things going on. He might have a dental issue and the bit could be irritating him and making him feel uncomfortable. Before you do anything else, you should have his teeth looked at by an equine dentist and get any issues fixed.
After you’ve ruled out a dental issue, you’re looking at a lack of training. Horses that constantly play with the bit are what I call “nervous between the ears.” What I mean by that is his mind is racing at a hundred miles an hour, not focusing on you, and that translates to him mouthing the bit. When a horse’s mind is busy, it usually means his mouth is busy.
When I’m riding a horse like this, I just ignore what his mouth is doing and focus on getting his mind to relax. The answer to getting his mind to relax is to move his feet forwards, backwards, left and right and always reward the slightest try. You’ll notice many people who have horses that chomp on the bit ride the horse in continuous laps around the arena. They basically put the horse on autopilot and do nothing to engage his mind. Do serpentines with the horse, practice rollbacks – get his feet busy and his mind focusing on what you’re asking him to do. You’ll find once he’s engaged in the lesson, his mouth will be quiet.
If the horse is gaping his mouth rather than playing with the bit, it’s because he is stiff and resistant to the bit pressure. Rather than training the horse – softening and suppling his body parts – head and neck, poll, shoulders, ribcage and hindquarters – most people resort to nosebands and cavessons to try to keep the horse’s mouth shut. Riding in a noseband will only cover up the real problem rather than fixing it by getting him soft, supple and responsive. There is no substitute for a good training program.
