EDUCATION

BASICS OF HORSE DENTITION
Samantha Mixon, D.V.M.

Why does a horse need dental work at all?
For the same reason you do, good health. Understanding anatomy plays a key role in understanding how and why dental problems occur in the horse. First, the upper jaw of a horse is always wider than the lower jaw. So even in the best of equine mouths the outer edge of the upper cheek teeth and the inside edge of the lower cheek teeth have no opposing tooth to wear against. Therefore sharp points form on the outside, or cheek surface, of the upper cheek teeth and on the inside of the lower cheek teeth against the tongue. These points can become so sharp that they cut cheek and tongue tissue causing ulceration and scarring of the mouth. I often cut my fingers when palpating the teeth during my initial exam. As these points become larger they also prevent the natural lateral movement of the horses jaw. The oral and dental anatomy of the horse is designed to rip and chew roughage, browse and graze, for 18-20 hours a day. The natural action of the jaw in a horse is to chew side to side in a circular motion NOT to chew up and down as humans do. These points are the most common problem inhibiting this normal chewing action but they are only one of several abnormalities that lock a horses jaw and force it to chew abnormally, up and down.

Secondly, a horse has 12 incisors, front teeth), and 26 to 30 premolars and molars, cheek teeth), as an adult. Looking at these numbers it quickly becomes apparent to most horse owners that the majority of their horse’s dentition is out of sight! This means that the majority of dental and oral problems are also out of sight.

Horse teeth are hypsodont teeth, which means that they grow continually during the life of the horse. Therefore they can continually develop reoccurring problems or new ones as the teeth grow. Humans, cats and dogs have brachyodont teeth which are one size for life and wear as we age. Horses need good yearly Oral Equilibration (returning the teeth to as normal contact as possible) or their teeth will not be with them in their twenties. Good thorough yearly dental care will extend the life of horse’s teeth by approx. 5 years. Dental care should start in horses as yearlings to prevent and correct problems and abnormalities.

Why does a young horse need it’s teeth examined?
Horses have 24 baby teeth called deciduous teeth that need to be shed before their permanent replacements, adult teeth, can erupt through the gum. Deciduous teeth that do not shed at the appropriate time are called retained caps. Caps being the term equine veterinary dentists give to baby teeth that should be shedding. A retained cap in any location predisposes the mouth to numerous short and long term consequences: (1) the eruption of the permanent tooth in an incorrect location because the baby tooth is in the way; (2) delayed eruption of the permanent tooth, causing malocclusion problems of the incisors and cheek teeth; and last but not least, (3) severe pain and discomfort resulting in eating and training difficulties. The deciduous equine teeth are shed and replaced by adult teeth from the ages of 2 to 5 years of age. Often I do not see a mouth until a horse is 6 to 8 years of age. At this point I cannot prevent any of the abnormalities caused by caps that were retained too long. All I can do is start to correct the abnormalities over time, which may take 2 years of corrective dental work every 6 months to correct. Correcting is usually more time consuming and expensive for the owner than preventing the dental problems in the beginning. Young horses deserve excellent dental care for another very obvious reason…THEY ARE IN TRAINING! Horses are put into training anywhere from 2 to 4 years of age. These first experiences will leave a lasting impression of how it feels to hold a bit in the mouth and will mold the responses to human commands. Often a “bad” horse or a “stubborn” horse is a horse trying to say, “This command /exercise is causing me pain”. There is no excuse to start training off on the wrong foot by putting the bit into a young tender mouth that has very sharp points on it’s cheek teeth. Deciduous teeth form the same very sharp points that the adult teeth do. The training messages should be consistent and a pleasant experience for the new trainee. The best program is to have a thorough dental exam and O.E. performed when the wolf teeth are removed at the age of two. Start your training off on the right hoof!

DEFINITIONS
EVD: Equine Veterinary Dentist, a veterinarian who specializes in dentistry.
Hypsodont Tooth: A tooth that grows throughout the lifetime of the animal. Found in horses and cheek teeth of ruminants.
Deciduous Teeth: Baby teeth of a horse.
Cap: A baby horse tooth that is about to come out, one that needs to be lost before adult tooth can emerge in the right position.
Retained Cap: A cap that is not being shed in a timely fashion and is causing abnormal eruption of an adult tooth.
Oral Equilibration: The correcting of dental abnormalities to bring the teeth back into as normal contact as is possible for that horse.

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