OPEN WIDE! Basic Equine Dentistry
By D. Craig Barnett, DVM, Intervet, Inc.
Humans probably interact more with a horse’s mouth than with the mouth of any other animal species. (Only a pet dog comes anywhere close, and then only if it is prone to giving somewhat unwelcome doggy “kisses” or retrieving wild game or tennis balls.)
The extremely sensitive part of the anatomy not only takes in food as the first link in the ever vital digestive system, it also holds the metal bit used to guide the horse in training and then in understanding its rider’s performance cues.
Among the most important pars of the mouth are the teeth. The horse uses its front incisors to bite off grass or scoop up grains. Its back molars grind the feed into bits small enough to swallow easily. We humans also use our horse’s teeth to help determine its age, and sometimes to sssist in detecting certain health problems.
Well-formed, strong teeth, without sharp edges or protruding points, are important to digestive health as well as to keeping a horse comfortable and willing to carry a bit without pain or discomfort.
Teeth Basics
A foal usually has all 12 of its deciduous (or baby) incisor teeth by age six to nine months. The youngster also will grow three premolar baby teeth in each upper and lower back jaw area, for a total of 12 grinding teeth. All of these 24 deciduous teeth will become loose and fall out as the permanent teeth begin to come in at about age 2.
A mature horse has six incisors in both the upper and lower front part of the jaws. The two central pairs, which appear first, are called centers, the two pairs adjacent to them are known as intermediates, and the outer four incisors are called corners. The last of the permanent incisors, or the corners, usually have appeared by age 4.
Further back are six cheek teeth on each side of each jaw, for a total of 24 molars or grinding teeth. Technically, the first three teeth in the row of six are called premolars and the last three are known as molars.
The gum area, or interdental space, between the incisors and molars doesn’t usually contain teeth and is where a properly-fitted bit should rest.
The number of permanent teeth also is determined by gender. Most male horses (and a few mares) have a lower and upper tooth on each side that is positioned between the corner incisors and the first premolar, often located near to the point upon which the bit should rest. These are called canine teeth or tushes.
Most stallions or geldings, therefore, have a total of 40 permanent teeth, while mares have 36. A horse is considered to have a “full mouth” at age 5.
In addition, a common rudimentary tooth, called a “wolf tooth” may erupt in the upper jaw of some horses just in front of the cheek teeth when a horse is five to six months old. As these teeth often cause problems when fitting a bit to the horse, they usually are removed.
Aging a Horse
The approximate age of a horse can be determined by studying the 12 front permanent incisors. This method requires education and practice to attain any degree of accuracy.In younger horses, the number of permanent incisors present will tell you if the horse is 3 (centers have erupted and are in contact, upper against lower), 4 (intermediates are present), or 5 (all are present and in contact).The next stage is determined by the “disappearance of cups”. Deep indentures, or cups, are present in the center surfaces of young permanent teeth. Because cups in the upper teeth are deeper than those in the lower, they wear at different rates and become smooth at different times.Generally speaking, the cups wear to a smooth surface first in the lower centers, then the intermediates and then the corners, followed by the upper centers, intermediates and corners at age 6,7,8,9,10 and 11 years, respectively. By age 12, a horse is known to be “smooth mouthed”.In addition, as the cups wear away, “dental stars” appear first as narrow, yellow marks in front of the central enamel ring. In older horses, these “stars” appear as dark circles near the center of the tooth.Another indication of age is the “angle of incidence”, formed where the upper and lower incisors meet (in profile view). The angle is approximately 160-180 degrees in younger equines and eventually changes to less than 90 degrees in older horses.As this angle changes, and the teeth appear to slant outward, the surface of the lower corner teeth do not wear all the way back to the back margin of the uppers. This “dovetail notch” usually is formed at about age 7, may reappear from age 12 to 15. At disappears for good soon after.Another sign of age is the Galvaynes’s Groove, a dark line which appears at the gum margin of the upper corner incisors at about age 10. By age 15, it extends aabout half way down the tooth, and reaches the wearing surface by age 20. The groove has completely vanished by age 30.Good Dental Care
Wise horse owners will ask their veterinarian to carefully examine their horses’ mouths and teeth at least once each year.He or she will look for a number of things, including, but not limited to, the following:·Sharp enamel points on the tooth which can lacerate the cheek or tongue;
Sharp enamel points on the tooth which can lacerate the cheek or tongue;·Hooks, located on the sides where teeth fail to completely com together, which can penetrate the soft or hard plate;
Hooks, located on the sides where teeth fail to completely com together, which can penetrate the soft or hard plate;·Infected teeth;
Infected teeth;·Retention of deciduous (baby) teeth;
Retention of deciduous (baby) teeth;·The presence of wolf teeth;
The presence of wolf teeth;·Long or extra tall teeth in older horses;
Long or extra tall teeth in older horses;·Malalignment of teeth (such as in parrot-mouthed horses);
Malalignment of teeth (such as in parrot-mouthed horses); ·Excessively sharp or tall canines that could interfere with the bit or cause painful mouth lacerations.
Excessively sharp or tall canines that could interfere with the bit or cause painful mouth lacerations.Owners and manager should watch for certain behaviors and actions that may indicate dental problems or disease and report them to their veterinarians.
These might include: increasingly poor athletic performance, excessive loss of feed from the mouth when eating, outright slobbering, difficulty chewing, bad breath (horses usually have sweet breath), head tossing, bit chewing, tongue lolling, tail wringing and sometimes even bucking.
Many of these problems can be solved by tooth removal, or, more commonly, by filing off the sharp surfaces with a special file. This is known as “floating” the teeth, and is usually done to most horses about once each year, often at the same time that the dental exam is performed. Occasionally it may need to be done more often.Because one of our main lines of communication with this amazing animal species is through its highly sensitive mouth, it behooves us to take good care of our horse’s teeth. His very health and happiness – right along with ours – depend upon it. 