Dental issues that can negatively impact your horse’s performance
DENTAL ISSUES THAT CAN IMPAIR EQUINE PERFORMANCE
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 behaviour 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 behaviours. 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).”
A QUICK ANATOMY LESSON
Horses have a hypsodont tooth structure, meaning teeth erupt throughout the horse’s lifetime. The approximately 40 teeth (not every horse has all types) include the incisors at the front of the mouth, the canine teeth between the incisors and the premolars, the wolf teeth immediately in front of the cheek teeth, and the premolars and molars than make up those tightly wedged cheek teeth.
When looking into a horse’s mouth, you can only see a small portion of each tooth, called the clinical crown; most—the reverse crown that continues to erupt over time—is below the gums, in the jawbone.
—The Horse Staff
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.
A horse whose jaws and teeth don’t align or meet in a uniform way can also experience performance problems. The most common malocclusion, says DeLorey, is wave mouth (an unevenly worn row of cheek teeth). Wave mouth can cause discomfort in horses that wear a lot of bitting or a tight or dropped noseband.
Some malocclusions, such as hooks that accompany wave mouth, can impede normal jaw motion during under saddle work. When the rider goes to collect the horse and asks him to flex at the poll, for instance, the hooks hinder movement in the temporomandibular joint (TMJ, which allows the horse to open and shut his mouth) between the skull and the first neck vertebrae, right in front of the poll, says Delorey.
Normally, when a horse flexes at the poll, the angle between the head and neck changes, causing the lower jaw to slide forward. If anything blocks that movement, such as hooks on the molars, and the horse can’t open his mouth enough to create space to free them, the jaws essentially lock together, the lower jaw can’t slide forward, and the horse can’t flex at the poll.
“Trying to force him to flex may create pain in the TMJ joint,” says Delorey. “This problem can generally be alleviated with proper dental care and by not forcing the horse to keep his mouth shut.”
A horse whose mouth is not forcibly closed when ridden can move his jaws to adjust their position and stay comfortable. In this case, the horse might not exhibit any performance problems, even though he may have hooks.
“There is very little science to back this up, but through years and years of working with performance horses and riders, I can … say that severe dental malocclusions (which are fairly common) play a significant role in how that horse is able to perform athletically,” says Delorey. “Some horses can handle these types of adversity better than others; some need to have everything perfect in order to perform optimally.”
In other words, some horses simply continue to do their job no matter what. They have a high pain tolerance or an especially stoic personality and continue performing in spite of a dental problem other horses might not tolerate.
Diagnosis: Easier Said Than Done
Identifying performance problems and determining their cause is often more art than science. “There is rarely just a single source for a performance problem,” says Delorey. “It’s usually due to multiple issues that have been building up over time. Often if you can correct one problem in the chain, however, some of the others will self-correct.”
Dental problems can accumulate to the point they become overwhelming to the horse, resulting in reduced performance. Diagnosing these cases, says Delorey, is a process of elimination.
“Most of my clients who are having difficulties with their horses come to me because they want to rule out dental issues,” she says. “If it’s not a dental issue, they can start investigating other problems.”
Jack Easley, DVM, MS, Dipl. ABVP, ADVC (Eq), owner of Easley Equine Dentistry, in Shelbyville, Kentucky, describes the typical diagnostic process when he’s dealing with a performance issue that could have its root in the mouth: “Diagnosing a dental problem is accomplished the same way you’d diagnose any other medical problem in the horse,” he says. “You start by taking a good history to find out the problem the owner, trainer, or rider is having with that horse.”
He also collects a general, medical, and surgical history on the horse and reviews concurrent problems such as nasal discharge, blood in the mouth, unusual odors, or eating issues. Any number of things can be associated with dental pain and undesirable behavior.
“Then you need a good examination of the horse—looking at his head, muscles of mastication (chewing), making sure his head and muscles are symmetrical on both sides, with no neurologic deficits,” Easley says. “A trained, experienced practitioner can do this in a matter of seconds.
“It’s important to evaluate the skeletal structure of the head, to make sure the jaw bones look and feel the same on both sides and are lined up straight,” he continues. “You want to be sure that the temporomandibular joints are symmetrical—the same size and conformation on both sides of the head.”
Easley says he then evaluates incisor alignment, looking for excessive wear, damage, or disease and any abnormal wear patterns.
“I also check the health of the gums, lips, cheeks, and tongue,” he says. “Then we proceed to a complete oral exam, and at that point we usually sedate the horse. You want them to be cooperative and relaxed, so you can get the mouth open and get your hand inside.”
Typically, the practitioner uses a speculum, light, and mirror to get a good visual on the oral cavity and dental arcades (top and bottom rows of teeth), feeling the teeth and all the soft tissue structures. “We can make sure everything is symmetrical, with no damaged teeth that cause uneven wear, no loose teeth, and no soft-tissue lacerations in the cheeks or tongue,” says Easley. “At that point, if we find anything that looks or feels abnormal in the mouth, we look a bit closer.”
This might include taking radiographs (X rays) to diagnose what’s happening beneath the gum’s surface.
For instance, “an elongated tooth has not been worn down properly, and this could be because it is malformed or malpositioned or the opposite tooth is damaged,” says Easley. X rays can reveal why the elongation has occurred.
Based on radiograph results, the veterinarian can design a plan for fixing the problem and maintaining the horse throughout his life. “Most of these issues keep recurring unless we address the root of the problem,” he says. “You can float teeth and take down the elongation, but this is just a temporary fix.”
Getting to the source of the problem and making and executing this maintenance plan can help the horse remain comfortable and rideable.
Many things can cause a change in your horse’s behavior, including dental problems. If your horse is uncharacteristically shaking his head, rooting in the bridle, throwing his nose in the air, tossing his head repeatedly, sticking his tongue out, or bracing on the bit, you might want to have your veterinarian perform a thorough oral exam.
Also remember that many performance issues are due to pain elsewhere in the horse’s body, so be sure to rule out other physical issues, as well.