
Horse Open Mouth When Riding
How many riders could have the theme from The Nutcracker accompanying their rides, for the constant snapping of their mounts’ teeth? As with life, when there is a problem there are two approaches: covering up the problem or addressing the root cause of the problem. When it comes to a horse channeling his inner nutcracker, searching for the root cause of opening mouths can be a frustrating and time-consuming process, but it is ultimately worth it.
Why Is My Horse Opening His Mouth?
Many people automatically reach for a different piece of equipment when their horse starts to open their mouth while riding. The first choices tend to be a stronger, tighter noseband, or a bit with more leverage. The problem with this approach is that it is akin to putting a Bandaid on a deep gash. The horse is opening his mouth to communicate something, maybe something as innocuous as “I don’t want a bit,” or something as serious as “my teeth are hurting me with every motion of the bit.” If we assume that the horse is just misbehaving, and we just shut his mouth more tightly or use a different bit, the problem that the horse is trying to communicate is not being addressed.
Identifying the Problem
The first thing that is easy to check is a horse’s teeth. Since they are constantly growing throughout a horse’s life, their chewing patterns can wear their molars in such a way that sharp hooks and edges can form on the sides of their teeth. These sharp points and edges can cut a horse’s cheeks and tongue. An easy way to check is to carefully slide your finger into the horse’s mouth, knuckle toward the teeth, and see if there are sharp edges on the molar. There may be other problems such as rotting teeth or sores from foxtails or foreign bodies that a vet can address. Another thing that is important to remember for a horse in training, or for a young horse, is the various dental changes that young horses go through. Horses shed their baby teeth between ages two and three, and the wolf teeth often erupt during this age as well. Furthermore, their jaws often grow at different rates, and a bit that fit them two months ago may be too small now. These teething issues can cause horses to be more mouthy, or cause mouth pain. As always, for any behavior problem, be sure to look for pain as a root cause and be ready to address it from a veterinary perspective.
No Problems There - What Next?
If there are no problems with the horse’s teeth, the next thing to address is equipment. The first and most obvious place to examine is the bit. This is a science all on its own, and The Ultimate Book of Horse Bits: What They Are, What They Do, and How They Work is an excellent resource for understanding how bits work. Many horses who don’t like traditional bits appreciate the Myler system of bitting. The designers of this system have written a book on it for more information, called A Whole Bit Better. While the answer is not to automatically try to tighten a noseband, some horses may benefit from a different noseb, such as a drop or figure-eight noseband, or simply removing the flash attachment. For a more full discussion of horse tack, there is more information in Horse Tack and Saddlery: The Complete Illustrated Guide to Riding Equipment and The Horse Tack Bible.
In general, it is best to use the gentlest bit that will get an effect, whether you are looking for a western bit or English bit. Many horses like a double-jointed eggbutt or mullen-mouth (straight barred) snaffle. These mouthpieces have a soft action on the mouth, eliminating nutcracker action that can put uncomfortable, pinching pressure on the bars and roof of a horse’s mouth. Some horses like a straight rubber-mouthed bit or plastic coated, apple-flavored bits, but not all of these bits are allowed for competitions in all disciplines. For horses that refuse to accept a bit at all, they may appreciate making a switch to a bitless bridle or hackamore.
Many horses show a huge positive change when switching to bitless options. Care must be taken however – each of these pieces of headgear work on different pressure points on the horse’s head, and each has action that is quite different from a bit and bridle. Your horse may need retraining, and especially with the hackamore, care must be taken to adjust it correctly to avoid injuring the nasal bone. Consulting with a trainer or other skilled professional is crucial when undertaking a quest to change equipment.
It Could Also Be...
And now we approach the hardest part of the equation: the image in the arena/tack room mirrors. The gentlest bit and most perfectly-fitted bridle can be torture if a rider’s hands are harsh and unyielding. Under saddle, a rider must remember to have soft, forgiving elbows and hands. Only then can the horse be encouraged to move its body properly and accept a comfortable contact with the bit. Here there is nothing that can replace another set of eyes to watch you while you are riding. An even better solution is having regular riding lessons to avoid forming bad habits when holding the reins and interacting with the horse’s mouth. For further reading on correct rider position, Sally Swift’s Centered Riding is a timeless resource. That said, no book can replace a pair of expert eyes on the ground watching you ride and correcting your mistakes.
Conclusion
If your horse is opening and closing its mouth while riding, that is a sign that something is bothering him, or has bothered him in the past and made him form a habit. Not only is it annoying and can cost points in competitions, but it can be a sign of pain and discomfort. Sometimes it’s a reaction to discomfort from riding, and sometimes it’s a reaction to discomfort coming from the equipment. It can take some creative thinking and detective work, but what greater price is there than your horse’s well-being? And what greater reward is there than having a happy, comfortable horse who can enjoy his job? Furthermore, it is not fair to a horse who carries us and gives us so much joy to ignore his attempts to communicate with us.
About The Author

Ani Petrak
Ani Petrak is a freelance linguist and writer based in the Czech Republic. A lifelong English rider and groom, she has experience showing in dressage, hunter-jumpers, trail, and young horse in-hand competitions. She is currently working with a Grand Prix showjumping and dressage trainer while raising and training her young warmblood gelding for a career in dressage, working equitation, and cross-country hacking.