Knox Equine Dentistry
Equine Tooth Problems & Dental Care EQUINE TEETH Horses' teeth grow continuously until some time between the ages of 25 and 30. Grass, their natural food, contains silica which is an abrasive and constantly wears down the horse's teeth. The fibers of heavier grasses require some grinding and the horse must reach down to bite off grass. It then raises its head to chew - which constantlychanges its jaw position . A horse living on natural grass will be more likely to naturally polish off the surfaces of its molars into a level plane. Thus the horse's dental apparatus is well adapted to its natural diet. In order to efficiently grind their food, horses' upper molars are spaced a little farther apart than their lower teeth. While important in the wild, this offset can produce problems in the domestic horse. Horses on alfalfa and less fibrous feeds tend to chew less and the material which they are eating is generally less abrasive. Accordingly, there will be surfaces which do not get evenly polished off. Raised edges (points) may appear along the edges of the molars typically along the outside of the upper set and the inside of the lower set (see image at irght). When these "unground surfaces" get large the horse cannot rock his lower jaw laterally as it chews between the opposing ridgesdue to his teeth being locked. The problem thus self propagates, the ridges slowly appear larger as they are no longer being worn down, and as the horse rubs these ridges when chewing, it is wearing down the sides of these ridges into sharp points. These points can be quite razor-like, actually cutting deep into one's finger when rubbed across them while inspecting the mouth. These sharp points often cut into the horse's cheeks when they chew and cause soreness where a bit or halter pushes the cheek against a sharp tooth. They can also cause slab fractures (see below). In some cases a horse may have to chew unnaturally in an attempt to grind up his food. This action can often result in increased uneven wear on the teeth and in some cases generate significant excess pressure on one or more tooth which can result in serious complications, including resulting is loosening of teeth. In addition, the now restricted jaw movement can result in hooks being formed on the first molars on each side of the upper jaw. Because of the limitation of chewing movement caused by the ridges, the horse tends to rock his jaw backwards. This results in the first molars being unevenly worn with the unworn portions hanging down like stalactites. By this time the horse is typicallynot grinding his food well, is experiencing discomfort in his mouth, and is probably lacking in nutritional efficiency. You can see from the sketch how wolf teeth and the forward hooks on upper molars would definitely cause some discomfort when the horse is carrying a bit in his mouth. \ The arrow points to hooks formed behind the last molars. These hooks prevent the horse from being able to move his lower jaw forward (which among other things, is necessary for collection and a proper headset.) \On the upper jaw, similar hooks form along the font edges of the first molars which also serve to "clamp" the jaw in place. This generates unnatural pressure on the temporo-mandibular joint (TMJ). The red arrows in the image on the right point to the temporo-mandibular joints on this skull. If you look closely you will see permanent damage to the joint surfaces which likely resulted in this horse having impaired motion and chronic arthritic pain. As these conditions develop the horse's teeth must be made level through use of a dental rasp. This process, called "floating," is the to rasping off of the excess tooth material in order to create a level "table" for the molars to come together. The type of rasp used varies according to the size of the horse's mouth and relative hardness of his teeth. If the conditions are allowed to get to severe, corrective dentistry will be required which involves specialized tools and knowledge. Note: It's not the dentist's intent to make the teeth completely flat. They need some irregularity in order for the horse to grind his food. The table (overall surface where the rows of teeth meet) must be reasonably level overall in order to allow proper jaw movement. (In the case of a missing tooth, the opposing tooth will erupt into the space where the missing one should be, causing some problems. The long tooth should be cut or filed to be the same length as the others.) If the hooks are too large, the rasp, or float, cannot make it past the hooks, so they will first have to be "rough cut" with a special dental tool. Once the floating is complete, the mouth should be checked to make sure the horse's canines (pointy teeth found behind the incisors in stallions and geldings) are not so long that they press into the opposing gums. If they have grown too long, they will need to be shortened. A grinding or dental cutting tool is used for this purpose. Some horses will also have wolf teeth. These are small premolars which appear on the upper jaw above and usually slightly ahead of the molars. These teeth are particularly troublesome as they are not set in the jawbone and the presence of a bit pressing against them can cause significant gum discomfort. If they are present, they should be removed by a veterinarian or equine dentist. SIGNS AND SYMPTOMS Your horse may be showing signs of burgeoning dental problems. Horses who become harder to keep for no apparent reason, who salivate excessively when eating, who eat slowly and with effort, who continuously drop bits of half chewed food, and who show unusually coarse manure are prime candidates for a dental inspection. Other behavioral characteristics suggesting tooth problems may include unusual fussing with the bit, avoidance of bit contact, irritation when put into a dropped noseband, head tucking or head tossing, poor self carriage, and not wanting to have its face and muzzle handled. PAIN AND BEHAVIOR An uneven matching of the molars can put a strain on the temporal mandibular joint, which can be very painful. In humans "TMJ" problems can cause headaches. In horses it can cause them to go off feed or colic. Oftentimes mysterious colics which have no apparent cause can be traced back to dental problems. Hooks on the far back of the molars can prevent the horse's jaw from relaxing and moving forward when the rider asks him to round up, especially if it's wearing a tight dropped noseband and can't open its mouth to relieve the pressure. This situation can also be painful and result in the horse displaying unusual head movements or being unable to sustain a comfortable frame. Additionally, young horses will often experience discomfort when shedding their deciduous (baby) teeth. Lumps will often appear under the jawbones while the new teeth are trying to erupt and sometimes the horse can benefit from some human assistance in removing the old baby tooth "caps". POST DENTAL CARE ISSUES Horses who have had significant dental malalignment can become very sore in the jaw after floating. The temporal mandibular joint, ligaments and support muscles will have adjusted to perhaps years of operating in an unnatural position. When the bite is corrected, the joint should return to a normal position in its socket which can temporarily cause a strain and pain to modified tissues. The horse may have difficulty chewing and grinding his food, in which case appropriate doses of phenobutezol (bute) should be administered and the horse supplemented with ground feed until the joint stabilizes and the pain subsides. This discomfort is not usually indicative of improper dental work and should subside in a few days and the horse should benefit from improved dental (chewing) function. THE POWER OF PREVENTION Most equine dentistry involves prevention. If your horse's teeth are regularly cared for, the maintenance process will not be overwhelming and you should be able to avoid most dental or health complications. Depending on your horse's diet, hardness of teeth and jaw alignment, it may need floating on an annual basis. By keeping an eye on your horse's teeth, you can determine how quickly your horse's dental surfaces are changing and get them cared for before complications arise.   Jamie