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We’re continuing our discussion of preventative care this week with a topic that is very near and dear to our hearts: Equine Dentistry. We get a lot of questions on this subject, so we thought we’d take some time to explain it, and why we think it is so important.

Let’s start with an introduction to the equine mouth. Horses have 36-44 teeth in their head (depending on gender and some individual variations):
– 12 incisors
– 4 canines (usually in males only, but occasionally in females… Dr. Leighton has a theory about that…)
– 2-4 “wolf teeth” (the first premolar, variably present, usually just the upper 2)
– 24 “cheek teeth” (premolars and molars, which act together as the main grinding surface).The incisors and cheek teeth erupt continually throughout the horse’s life (we sometimes say the teeth “grow” continuously, but that’s not exactly correct – in adult horses, all the tooth is already “grown”). It’s necessary for their teeth to continually erupt like this, because horses slowly grind down their teeth on their coarse diet. As they chew, and the teeth are worn down, more tooth erupts to replace it. It’s a pretty neat system, huh?

Unfortunately, most horses don’t wear their teeth down evenly. The outside of the upper teeth (along the cheek surface) and the inside of the lower teeth (along the tongue surface) usually don’t make full contact with the opposing tooth. Therefore, these edges don’t get ground down; instead, they can develop into sharp points. These “enamel points” can irritate or even cut the cheek and tongue. The points should be filed down on a regular basis to prevent damage to the mouth. This is usually referred to as “floating” the teeth.

(Did you know that the term “to float” originated from masonry? It was used to describe smoothing or leveling of plaster. So, we are “smoothing and leveling” horse teeth. Thanks, masons!)

Now, if sharp enamel points were the only thing that could happen to a horse’s mouth, equine dentistry would be pretty simple. But, there’s a lot more to it. Since horses chew in an elliptical motion (side-to-side, and smaller amount back-to-front), if their molar surfaces are not fairly level, the motion will be interrupted. If a horse can’t properly chew his food, esophageal obstruction (“choke”) or colic can arise. An overgrown cheek tooth is the most likely cause for this motion to be disturbed. At the back or the front of the mouth, this overgrown molar is called a “hook” or “ramp”. If a tooth is fractured or lost, the opposing tooth will not be ground down properly, and as it grows long we call that a “step”. Another common abnormality in older horses is a “wave mouth”, where the entire grinding surface rises and falls in a wave pattern.

In general, as horses age and their teeth continue to erupt, their molar roots shorten. Molars may shift, become loose or be lost entirely. Loose teeth sometimes need to be removed to increase the horse’s comfort while eating. Teeth that have shifted may create gaps between the teeth (“diastema” – see picture to right), which packs with feed material, causing periodontal disease or pocketing. These diastema can be widened to allow feed to enter and leave freely, and the periodontal disease can be treated with flushing and antibiotics.

And let’s not forget, the cheek teeth aren’t the only teeth in the mouth! Incisors sometimes need correction, too. Mild corner hooks, which are normal in middle aged horses, can sometimes interfere with lateral movement, and should be adjusted. Loose incisors are fairly common in older horses, especially related to a specific disease called “Equine Odontoclastic Tooth Resorption and Hypercementosis”. (Which is a whole ‘nother blog topic!)

So, as you can see, there can be a lot going on in a horse’s mouth! That’s why it’s recommended that each horse have an oral examination once yearly, regardless of age or use. Most horses need a dentistry once a year, but there are variations – some horses with very good mouths can be done every other year, while older horses with “wave mouths” or loose teeth are better done twice yearly. To fully evaluate a horse’s mouth, a full-mouth speculum should be used. This is a device that fits into the horse’s mouth, over the incisors. When opened, it keeps the jaws of the horse apart so that we can insert our hand, a mirror, and our equipment without injury to ourselves or the horse. We use a bright light and a dental mirror and probe (as well as our fingers!), to fully examine all surfaces of the teeth. Without a speculum, we can peak at a horse’s mouth, but we really can’t see everything.

To correct any abnormalities we find, and file down the inevitable sharp enamel points, we use a combination of motorized equipment as well as the more traditional “hand floats” (which look like files, or small rasps), as necessary. We prefer using our motorized PowerFloat(R); in our hands it is fast and safe, and we feel we can do a more complete job using this tool instead of hand floats. We do this procedure under safe, standing sedation. A padded free-standing head stand is used to rest the horse’s chin (which reduces work for the assistant, and helps keep the horse’s head stable for any fine adjustments). Before any corrections are performed, we perform a full oral examination, using a bright light, mirror and picks. Loose or shifted teeth are evaluated to see if any extractions are necessary. Incisors are evaluated, and corrections made if necessary. Diastema or periodontal pockets are probed and evaluated, flushed and packed as necessary. Enamel points are reduced using the motorized equipment, and teeth that are longer than normal (causing a step, ramp, hook or wave) are reduced to normal level *if possible*. (Keep in mind that in some cases, there is a limit to how much tooth we can remove at one time without damaging the tooth. If the tooth is too long, we’ll take a safe amount of tooth off, then recommend a second visit in 3 months, to allow the tooth root to regress before we take more.)

Some of the concerns we sometimes hear regarding motorized dentistry include: it can be unsafe, take off too much tooth, overheat the teeth, etc. If motorized equipment is used by untrained individuals, those are absolutely valid concerns. The reasons we love motorized equipment are exactly the same things that allow it to be abused: it is quick, and teeth can be removed with relatively little physical effort. With improper training, it is absolutely possible for someone to remove way too much tooth, or heat a tooth to the point of damaging it. We take pride in our experience using this dentistry method. We know how to use the equipment safely and effectively. Used properly, motorized equipment can actually be less traumatic to the mouth than traditional handfloats.

So, how do you know your horse might need a dental? The signs may be very subtle or very obvious. Some horses will drop feed, “quid” their hay (meaning they spit out partially chewed wads of hay), or even hold their mouth open awkwardly when they have a dental problem. But more often, very slight behavioral changes are noticed, such as an attitude change, or resistance to the bit or flexion of the head and neck during riding. Weight loss or increased fiber length in the manure are sometimes noticed (see picture). Occasionally, severe abnormalities are found without any symptoms of discomfort. Dr. Leighton once removed two sticks imbedded in the roof of a horse’s mouth, which she found on a routine oral exam – the horse had not shown his owner any indication that his mouth was bothering him!

Just remember – a yearly oral exam, and dentistry as needed can go a long way to keeping your horse healthy and happy. Regular dental care from a young age can help prevent some of the “train wreck” mouths we sometimes see in older horses, with out-of-control waves and steps. It also reduces the risk of choke and colic, and allows that hay you spent good money on to actually nourish you horse. What’s not to like?