By Kimberley French
The mouth of a Thoroughbred is the principle means of communication between the horse and his rider. Other aids are used as well, but for many, the bit is what determines direction, rate of speed and position or frame in which the horse moves.
The design and function of the horse’s mouth is such that it provides a perfect vehicle for use as a “steering device.” The interdental space allows a bit to lie comfortably without interfering with the normal position of the jaws when they close. Horses are the only domestic animals that have their mouths used in this fashion.
Dr. Jack Easley, DVM, MS, Diplomat ABVP, who specializes in equine dentistry and resides in Shelbyville, Kentucky, insists the domestication of horses is the prime reason they require dental care.
“Typically, horses keep their heads on the ground and eat grass 16 hours a day,” Dr. Easley said. “But we keep them in a stall with their heads up and feed them hay, oats and sweet feed. Stabled horses tend to have more problems with periodontal disease and abnormal wear because their teeth have not adapted from their natural forage diet.”
Dr. Easley recommends preventative dental care long before a young horse is introduced to a bit. “An oral examination should be performed the day a foal is born,” Dr. Easley said. “You want to make sure the jaws match and there is no deformity in the head.”
A foal's deciduous premolars are all in use within the first few weeks of life and can soon start to wear abnormally if they do not mesh properly. While there are orthodontic devices and surgical remedies to correct truly severe over- and under-bites, they are expensive, difficult to maintain and have variable rates of success.
A foal should be examined again when it is weaned to make sure no teeth are missing from trauma, such as a kick in the mouth, and that all teeth are still properly aligned.
Unless there is an obvious problem, such as holding the head to the side, loss of feed while eating, nasal discharge or swelling of the face, jaw or mouth, a horse does not need to be examined again until it is ready to be bitted, which for a Thoroughbred is usually when the horse is a yearling or a 2-year-old.
When a horse is nine months old, all 24 baby teeth are in place. At this age, most horses will also erupt two wolf teeth and the first permanent molar set erupts behind the baby premolars. By the time the foal is a yearling, he has erupted 24 to 30 teeth and all of the deciduous teeth have been “in wear” long enough that their edges are likely very sharp. Deciduous teeth are softer than permanent teeth and wear sharp edges much faster. It is not uncommon for yearlings to have ulcers or lacerations on their cheeks and tongues from these razor-sharp points.
The first consideration prior to placing a bit in a horse’s mouth is to be sure there are no abnormalities within the mouth that may cause discomfort.
“Trainers should have their veterinarians do a performance float of their horse’s teeth before he is broken,” Dr. Mary DeLorey, DVM of Kettle Falls, Washington, said. “They will remove all sharp edges and round the front corners of the first cheek teeth, both upper and lower. This allows more room for mouth tissues and reduces discomfort when the reins are tightened and bit pressure is increased.”
A wolf tooth is a pointy little tooth located in the bit seat of a horse’s mouth. Much like a human appendix, the wolf teeth are evolutionary holdover, with no real function. The crown and root of the tooth are usually quite small.
A horse can get up to four wolf teeth, which are almost always removed during a performance float because they can interfere with bit placement. They often become “blind” or unerupted and can be felt as little bumps in the gums.
A horse's mouth undergoes the largest turnover of deciduous to permanent teeth between the ages of 2 and 3 1/2 years. He will lose two sets of deciduous incisors and shed two sets of premolars, all to be replaced by permanent teeth. He will have already erupted his second set of permanent molars, and the third set may be getting ready to erupt by 3 1/2 years of age.
According to Dr. Jon W. Gieche, DVM, the shedding of baby deciduous teeth is a complex process that can be hastened by normal chewing forces and delayed or accelerated by abnormal chewing forces. If chewing forces are reduced, breakdown might be slowed. If the adult tooth is not present, breakdown occurs anyway, but at a reduced rate. In some teeth without adult counterparts, the deciduous tooth might remain functional for years beyond its normal life.
Premature loss of a deciduous tooth results in abnormal development of the adult tooth and should only be removed if the adult tooth is present or a loose deciduous tooth can easily be wiggled.
If chewing forces are abnormal, tooth attrition is abnormal. In such a situation, eruption is uneven, with some teeth erupting faster than others. The faster erupting teeth become longer than others, resulting in hooks, ramps, steps, and waves. Without outside intervention, these conditions become progressively worse. They can result in many other complications such as cavities, periodontal disease, and pulpitis (inflammation of the dental pulp, which is located in the central cavity of a tooth). This can lead to premature loss of teeth.
Dr. Easley compares this scenario to human babies cutting their teeth and thinks it’s essential that young Thoroughbreds receive oral exams every six months. “Oftentimes, we are asking horses to perform while they are experiencing the pain and headaches that are similar to a baby’s teething,” Dr. Easley said. “Babies are cranky and can’t sleep at night when their teeth come in. A horse is going through the same thing; it just can’t cry to let us know it’s in pain.”
These signs could indicate a young horse in dental distress:
∙ Loss of feed from the mouth while eating, difficulty chewing or excessive salivation.
∙ Weight loss or loss of body condition.
∙ Large or undigested feed particles (long stem or whole grain) in the manure.
∙ Head tossing, bit chewing, tongue lolling, fighting the bit, resisting the bridle.
∙ Poor performance, such as lugging in, failure to stop or turn, even bucking.
∙ Foul odor from the mouth and nostrils or traces of blood in the mouth.
∙ Nasal discharge or swelling of the face, jaw or mouth.
While cheek teeth fractures are an unusual occurrence, they can be responsible for many dilemmas for a horse, from difficulty chewing to bad breath and can cause behavioral problems when pressure is placed on the sides of a horse’s face from the reins.
In an attempt to gather more knowledge on the treatment, management and frequency of this condition, the University of Edinburgh, in Scotland, sent a questionnaire to veterinarians and equine dental technicians. The survey results concluded that 147 horses suffered 182 total fractures. More than 70 percent of the fractures occurred in the upper mandible or jaw and where discovered in roughly .07 to 5.9 percent of all horses examined.
Weight loss and food impaction in the inner cheek are acute complications linked to cheek teeth fractures. Thirty-three percent of the horses examined during the study were unable to eat properly, 29 percent experienced biting and other various behavioral problems and 12 percent had halitosis. However, 39 percent of horses that had sustained a cheek tooth fracture presented no symptoms and were discovered through routine dental care.
The most common method of treatment was extraction of the small dental fragment. Other methods of treatment included extraction of the entire tooth; eradicating sharp edges on the fractured tooth; reducing the height of the opposing tooth; referring the case for other treatment; or not treating the tooth in any way.
After treatment, 81 percent of the diagnosed cases had no further symptoms, 13 percent had no clear-cut outcome and only 6 percent still had continuing complications.
In order for horses in training and racing to remain happy and healthy, it is critical to ensure they are able to work and perform in comfort. Comprehensive dental care delivered regularly by an experienced veterinary professional may be one of the easiest ways to maximize a horse’s performance and optimize his health for a lifetime.