Horses display dental problems with a wide variety of symptoms. While some symptoms obviously originate in the mouth, others are not so apparent. Symptoms can include (but are not limited to): excessive food spillage or difficulty chewing, long pieces of hay or undigested grain in the manure, excessive salivation (drooling), loss of condition or weight, bad breath from the mouth or nose, head tilting, resistance to or chewing the bit, tongue lolling, nasal discharge, bucking, tail wringing, head shaking, and poor performance. If your Reining horse resists stopping, your Barrel horse doesn't complete a turn, or your Hunter starts to resist the introduction and signals of the bit, these performance problems can be a sign of a painful mouth. Correcting dental problems can improve condition, digestion, and athletic performance.

As grazing animals, horses have a mouthful of wonderful grinding teeth called molars and premolars also known as cheek teeth (see fig. 1).

Figure 1. Skull of a 2-year-old, modified to show canines (C) erupted. Premolars are labeled in Roman numerals II, III, and IV (wolf teeth(PMI)are indicated by the arrow). Molars are labeled 1, 2, and 3. Deciduous caps are shaded dark.

The front teeth (incisors) cut hay and grass, while the cheek teeth chew the forage to a size small enough for digestion. Because of the way horses chew their food (with a side to side motion of the jaw), and the way their jaws are set, the most common dental problems are sharp points on the cheek teeth. Usually, the cheek side of the upper teeth and the tongue side of the lower teeth are the most severely affected. These points can cut into the tongue and cheeks, making chewing an uncomfortable or painful ordeal. These points must be floated or rasped off or greater problems will develop.

As with most physical problems, the type of dental problems seen often depend on the horse's age. Young horses have baby teeth (deciduous teeth), which shed as the permanent teeth erupt through the gums (see our table Tooth Eruption Times, on the following page). One common dental problem occurs when the deciduous teeth are not shed; this is known as a retained cap (fig.1). When a cap is retained the horse can have difficulty chewing. If the problem is long standing (chronic) and involves an upper cap, there may be painful swelling on the upper bridge of the nose. If a retained cap occurs on the jaw, a hard bump may develop on the lower surface of the jaw bone, in addition to chewing problems. These caps must be pulled to allow the permanent tooth to erupt completely.

Another dental problem often seen in young horses is caused by the wolf teeth. These small first premolars (PMI) are directly in front of the upper cheek teeth (fig. 1), (not to be mistaken with canine teeth) and often interfere with the bit. Many trainers routinely have these teeth pulled, instead of waiting to see if a problem develops.

Between the ages of two and five, horses will erupt 24 cheek teeth, with as many as 16 teeth erupting at the same time! For this reason, horses in this age group need dental exams more often than older horses. A good rule of thumb is similar to what human dentists advise: have the teeth examined every six months. Also, horses going into training should have in depth dental exams before training starts, so that a dental problem doesn't become a training one.

As horses mature we see other types of dental problems more frequently. Unfortunately, most dental problems occur due to inadequate maintenance when the horse is a developing youngster. Some of the more common problems seen with mature horses are "wave mouth" (fig. 2), "step mouth" (fig. 3) and 'hooks" (fig. 4). These problems occur because the grinding (occlusive) surface of the teeth do not meet and wear property. When this situation goes uncorrected the surfaces wear unevenly over time, causing some teeth to be too long and others to be too short. The result is poor chewing and, if neglected long enough, the long teeth can dig into the palate and gums. Other, less common dental problems include extremely long hooks, broken teeth, and abscessed or infected teeth.

Figure 2: Wave mouth

Uneven occlusive surfaces on mature horses require much more time to correct, and corrections are not always possible. These problems are perhaps the most dismaying, because they are the result of negligence from inadequate knowledge of proper dental care.

Figure 3: Step mouth

Our general recommendations for frequency of exams follow the recommendations of the American Association of Equine Practitioners and are: every six months for horses between two to five years old and horses in their 2's; yearly for horses between age five through the mid teens. Horses with dental problems at any age may need to be seen more often.

Like humans, most horses don't enjoy a dental exam. To avoid injury to horse and humans, some sort of restraint is necessary. Even with the use of a mouth speculum, not all the molars can be seen and must be examined by touch. The more thorough an exam is, the more likely we can spot a problem. Often, the more resentment a horse displays during a dental exam or procedure, the more likely there is some degree of pain involved with their teeth. These behaviors indicate the need for a thorough exam.

Although the floating procedure is not painful, lacerations may be present on the cheeks or tongue which will be painful. Often, the vibrations of the float frightens some horses. For many horses, sedatives can relax the animal, keep it more comfortable during a dental procedure, and eliminate the fear involved if there is pain. A complete dental examination cannot be accomplished by just feeling the first cheek teeth and looking at the incisors. In an effort to decrease the fear and anxiety many horses experience with a dental exam or procedure (not unlike many people), and because of the high safety of sedatives today, we sometimes advise tranquilizing horses for floating or dental procedures. While some horse owners hesitate to have their horse tranquilized, the use of sedatives can often allow the veterinarian to do a more thorough job in less time, and with less struggle, than it will take when working with a fearful or resentful horse.

Figure 4: Sharp hooks. The front of upper PMII and rear
of lower M3 have long, sharp hooks from malocclusion.

For more detailed information about dental care, eruption times, and aging a horse by its teeth, consult your veterinarian or feel free to call us to request the handout on Equine Dentistry.

Ron Friedman, MS DVM