Your usually soft-in-the-mouth, responsive gelding has started throwing his head in the air when you pick up the reins or ask him to collect. While the behavior might be frustrating for you as a rider, it could be just as frustrating for him: His teeth might hurt. Anytime a horse shows a sudden change or resistance when working with a bit in his mouth, you should have your veterinarian check his teeth.
A horse’s teeth are crucial not only for proper chewing and nutrition but also for proper performance. Dental problems can be quite painful and, in turn, can cause horses to exhibit certain performance-inhibiting behaviors. Often these problems are subtle or not even recognized as related to the teeth. So in this article we’ll list some of the dental issues to watch for and how they are corrected.
Sharp Enamel Points
Mary Delorey, DVM, of Northwest Equine Dentistry, in Seattle, Washington, says most dental problems that translate into performance issues are conditions that cause pain. The most prevalent one injures the soft tissues of the mouth.
“Normal wear of teeth can lead to sharp points,” she says. “These are probably the most common problem, since the lower jaw is about 30% narrower than the upper jaw.” Because of this disparity, the outside edges of the upper teeth and the inside edges of the lower teeth don’t wear away as fast as the rest of the surface during chewing, leaving very sharp points of enamel.
“Horses need a certain amount of exposed enamel to grind up food,” Delorey says. “In the wild, those sharpened projections don’t create much problem, but when we put tack on the horse’s face and a bit in the mouth, this changes things.”
Headgear such as bits, nosebands, and cavessons can place direct pressure on soft tissues that wouldn’t otherwise be subject to them.
Delorey says sharp points particularly affect horses that hold tension in their jaw muscles, either when ridden or stabled—similar to people who habitually clench their jaw. Thus, veterinarians perform routine dental care with two goals in mind: maintain dental health and provide comfort for the horse.
“Routine dental care involves floating (rasping), smoothing off those sharp points,” says Delorey. “Sharp top teeth can lacerate the cheek tissue; sharp bottom teeth can lacerate the tongue. The horse’s tongue is huge and long, nearly filling the oral cavity when the horse’s mouth is closed. There is no place for that tongue to go to get away from … sharp points on the teeth if the mouth is being held closed by tack.”
Regular dental care to remove sharp points can help eliminate resistance behaviors such as mouth-gaping, jaw-moving, or sticking out the tongue when being ridden, she says.
There has been and continues to be controversy about the presence, absence, and shape of wolf teeth—the first premolars, located near where the bit sits.
“Many people feel that those teeth don’t cause a problem as long as they are not sharp,” says Delorey. “This may be true, but a lot of horsemen prefer to remove those teeth when the horse is young, to eliminate them as a possible cause of pain and bad behavior. In my practice I routinely remove wolf teeth from many young horses destined to be performance horses. If I encounter wolf teeth in an older horse (e.g., mid-teens), and the horse is not experiencing any issues with the bridle or bit, I leave them alone.”
Some young horses enter training with their wolf teeth, then begin developing problems when they’re 4 or 5 years old. “At that age, it can sometimes be more difficult to remove wolf teeth because their attachment to the surrounding bone is stronger,” says Delorey. “Older wolf teeth are more likely to be broken, due to excessive pressure from the bit.”
She’s found that unerupted wolf teeth can cause more pain than erupted wolf teeth. “The teeth that are still under the gum surface are usually not in a normal position and more likely to be pressed by the bit since they are commonly located farther forward than a normally erupted wolf tooth,” she says. “Unerupted wolf teeth do not have a normal attachment ligament and are not as stable. My observation is that these teeth can be more painful if there is not a stable, strong structure under the gingiva (gum tissue surrounding the base of the teeth).”
It takes an experienced eye and familiarity with all the mouth tissues to check for these problems. “It also involves listening closely to the client and how the client experiences what the horse is doing,” says Delorey. “I look into the horse’s mouth, and instead of saying, ‘Oh! Look what I found!’ I ask the rider whether he or she thinks the horse is balanced in the bridle. If they say yes, then I don’t worry about that tooth. If the rider thinks the horse has some resistance in the bridle, I ask which side they are feeling more resistance in. That way, I am not biasing their answer. This helps me decide whether wolf teeth need to be modified or removed.”
An apical abscess (infection of the tooth root), a fracture, or periodontal problems (those affecting the gums and structures surrounding the tooth) can all cause a tooth to become diseased. “These must be evaluated on an individual basis,” says Delorey. “If the diseased tooth is in the front of the mouth, where it may be in direct or secondary contact with the bit or tack, it may be causing pain. Many diseased teeth, however, are much farther back in the head, far away from the bit and often nowhere near contact with any pressure from the bridle. Those have to be evaluated to determine whether they are causing a performance problem, and this can be tricky,” partly because many horses don’t react like humans do to a toothache.
“Horses are very tough animals and very stoic,” says Delorey. “They often keep doing their job and tend to keep eating, unless there is a very serious problem in the mouth. It has to be very serious, or a mechanical impossibility, for them to stop eating. Sometimes performance-related issues that are dental in origin can be quite subtle and almost impossible to confirm.”
She says she’s seen many horses with severe apical abscesses resulting in sinus infections still perform normally. “The owner may not know anything is wrong until the horse has a nasty nasal discharge on one side,” she says. The infection didn’t cause enough discomfort for the horse to act differently.