California Riding Magazine • December, 2008

Straight From the Horse's Mouth
Do you know what is happening
in your horse's mouth?

by Dr. Kim Sergent

Have you had your horse’s smile checked lately? Each horse, even youngsters, should have a full dental examination once every 12 months, or more frequently if they have had previously identified problems. A dental exam generally requires sedation and a speculum. After six months a brief exam should also be performed.

A typical exam would include an external check of the mandibular or maxillary (lower and upper jaw) for growths, swellings and symmetry, pain at the temperomandibular joints, forward/back and lateral excursion (does the jaw move freely side to side) of the jaws. Inside the mouth there are several oral cavity issues to check.

Your veterinarian should address alignment and abnormal wear patterns including diagonal incisors and overbites or underbites. Also, missing, damaged or discolored incisors should be checked. Gum disease such as gingivitis or abscessation can be seen in association with the incisors. Baby (or deciduous) incisors that have not been pushed out by erupting permanent teeth can be identified and removed. These can cause long term alignment problems as they may force the permanent teeth to erupt in an abnormal position if not taken care of.

Cheeks, lips, gums and tongue should be checked for any abrasions, abscesses and ulcerations caused by sharp points, hooks, ramps or foreign bodies such as grass awns or an ill fitting bit. Growths, such as melanomas, can sometimes be found on the lips and cheeks
as well.

Canine teeth are primarily found in males, these are sometimes very tall or sharp and can irritate or lacerate the tongue. Reduction of the canines will also aide in placement or removal of the bit. Excessive calculus or tartar often builds up on these and leads to gum disease (gingivitis) or worse if not removed.

Wolf teeth, premolars found just in front of the first cheek tooth (what we call molars), are often removed prior to training in order to avoid pain with the bit. Unerupted wolf teeth can cause problems too as there may be pressure on the gum overlying the teeth from the bit.

A Molar Dilemma

The majority of dental problems in adult horses occur in the molars (and premolars). This is where your veterinarian will be able to see the amount of molar occlusion or the percentage of the molar surface that is in contact during eating. Normal occlusion would be 90-100 percent of the width of the molars involved in grinding. The smaller the percent the less surface area is involved and the less efficient the grinding will be and the more abnormalities will arise.

These abnormalities include hooks, points, steps, retained deciduous premolars or caps, excessive ridges, cupping, ramps and waves.
Hooks are spikes on the front or back of a tooth. They can be found on the first and last molars, and they interfere with the front to back movement of the chewing cycle. They can become so severe as to impinge on the soft tissues, creating pain. This will also interfere with poll flexion.

Points are sharp edges on the inner lower molars and outer upper molars. These often cause ulcerations on the cheeks and tongue and can inhibit the sideways portion of the chewing cycle. This is the most common problem we see in young horses. Another problem in young horses are retained deciduous premolars or caps. Baby teeth that are not yet shed when the permanent teeth try to erupt. These often have sharp edges and can cause discomfort.

Steps are areas where one molar is dramatically taller or shorter than its adjacent neighbor. They inhibit forward and backward movement. Excessive ridges, taller than normal ridges across the biting surface of the tooth, can also inhibit this movement.

Cupping is when the center of the tooth is hollowed out or concave with only the edges coming in contact with the opposing tooth. This decreases the chewing surface area. Cupped teeth are nearing the end of their life so a diet that requires less grinding is in order to preserve the teeth.

Ramps occur when a tooth wears down and eventually slopes. They are common on the first and last lower molar. These can wear down the upper opposing tooth to nubs or dig into the upper gum. Ramps can interfere with the entire chewing cycle, as well as waves. Waves are an undulating biting surface with the teeth in the center of on arcade being taller than normal and overwearing the opposing arcade.

Worn Down?

Most molar and incisor abnormalities will affect the normal oval chewing pattern in the horse to some degree. Once abnormal chewing occurs a chain of events follows which lead to the eventual loss of optimal health and/or discomfort. If a horse cannot chew his feed into smaller size particles before swallowing, there will be less surface area for stomach enzymes to work on, thus decreasing the digestibility of the feed. This affects the amount of nutrients and calories absorbed and ultimately results in weight loss, ill thrift or even colic. Pain may occur within the mouth or at the TMJ, which may make a bit uncomfortable and will ultimately affect the horse’s ability to flex its poll and therefore its general ability to perform will suffer.

Many of these problems will require several visits to correct so as to not injure the teeth. Reducing the abnormalities early will require less intensive dentistry and fewer dental visits. Horse teeth, unlike human teeth, grow continuously until their mid 20s when the growth eventually slows and then stops. Their roots are generally deep until they are close to expiration.

Wear of the teeth continues even after tooth growth slows and abnormalities within the mouth will be accentuated. Tooth loss comes from damage to the tooth roots from infectious causes or a tooth under excessive force which damages its nerve. Once the nerve is so traumatized that it cannot recover, the tooth dies and eventually loosens. The loosening or loss of a tooth can then cause infection in the jawbone, gums, adjacent tooth root or the sinus. These changes can occur rather quickly, often within a few months. Abnormal mastication, foul oral or nasal odor, dropped feed and nasal discharge can occur even to the point of causing systemic illness.

You may ask why wild horses don’t need dentals. One answer is their life expectancy is typically much shorter than domesticated horses. This will effectively reduce many age related changes from ever occurring. Natural selection also has weeded out those horses with poor dentition. A horse with good dentition will last longer and breed more, passing on those good teeth. Also, wild horses graze on grasses that contain silica (which acts as fine sandpaper), which would tend to wear the teeth naturally as opposed to our hay and refined feed.

In the end if domesticated horses are given good routine dental care throughout their lives they will live healthier and we can enjoy our equine companions longer.

For more info call All County Equine Services (A.C.E.S.) at 619-659-3532 or visit www.acequine.com.