How long have you owned a horse?
Thirty years or more? You probably remember your veterinarian “floating your horse’s teeth” with a bucket of water and couple of hand files that he used to smooth down sharp points. Your vet kept your horse’s mouth open by pulling your horse’s tongue to the side. If that didn’t work, your vet might have slipped a small metal device between the molars on one side that prevented your horse from biting down. Most horses tolerated the procedure without sedation.
[MORE: PROPER EQUINE DENTAL CARE]
Twenty years? “Floating” rapidly became “dental balancing,” complete with power tools and a large metal speculum in your horse’s mouth to hold it open. Major adjustments were made to your horse’s bite that often involved cutting down the incisors (front teeth) to improve the contact of the molars (back teeth). This procedure was often necessary due to the amount of tooth removed from the surface of the molars. Sedation was almost always necessary. Because many vets weren’t comfortable with this type of dental care, “lay dentists” became popular and often traveled from town to town or even state to state to perform dental work.
Ten years or less? The pendulum has swung back after veterinarians began to recognize the severe tooth damage that resulted from overly aggressive dental work. Power tools and a full-mouth speculum are still the norm—along with routine use of dental mirrors or even a specially designed oral endoscope that allow your vet to perform a thorough and detailed examination. Skilled dental practitioners avoid excessive tooth removal and damage. Sedation is still almost always necessary for a thorough dental exam and treatment—and dental expertise is a huge component of many veterinarians’ training.
So why all the changes? And how do you determine what’s right for your horse? After all, it’s hard to see what’s really going on inside his mouth.
Here, I’ll help you wade through dental-care facts. First, I’ll go over tooth anatomy. Then I’ll give you important information that will help you evaluate the pros and cons of today’s treatment trends. Finally, I’ll bust seven myths you might have heard about equine dental care.
Knowing how your horse’s teeth are put together will help you understand why some adjustments are essential, while others might be unnecessary or even damaging.
First, let’s go over tooth composition. Teeth are composed of three tissues: enamel, dentin, and cementum. Enamel, the hardest tissue in the body, is important to the teeth’s grinding function. Cementum, the softest of the dental tissues, acts as a protective covering and helps to anchor the tooth to the periodontal ligaments (tissue fibers that connect tooth to bone). The bone-like dentin makes up the tooth’s major bulk. At the center of the tooth is the pulp cavity, where blood vessels, nerves, and other soft tissues lie.
Now let’s move on to structure. Be aware that you and your horse have very differently structured teeth. You have brachydont teeth, composed of a low crown above the gums and a root below the gums. The crown is covered by enamel, and the root is surrounded by cementum. Dentin fills in the space below the enamel surface and surrounds the entire pulp cavity.
Your horse has hypsodont teeth, which are composed of a high crown and multiple folds of enamel and dentin, with cemetum filling in the gaps. Each tooth is divided into the clinical crown (the portion of the tooth that’s visible above the gum line), reserve crown (the portion of the tooth contained within the jaw), and root.
Unlike the surface of the brachydont tooth, which is completely covered by enamel, the surface of the hypsodont tooth is made up of ridges of enamel, dentin, and even some cementum. Because of their varying hardness, uneven wear of these tissues results in an irregular occlusal surface (the part of the molar used for chewing or grinding), which helps your horse grind coarse materials, such as hay and pasture grass.
Human and equine teeth also differ in how they grow. To accommodate a grazing lifestyle, your horse’s teeth continue to erupt (push up out of his jaw) throughout his lifetime, until no reserve crown remains. This eruption compensates for teeth he grinds away by chewing. It also contributes to the development of dental irregularities that might require dental treatment, such as sharp points on the molars’ edges or tooth overgrowth on the opposite side of a missing tooth.
Horses have three usable types of teeth: incisors, premolars, and molars. They use six upper and lower incisors (front teeth) to grasp and tear food, and six upper and lower premolars and molars (cheek teeth) for grinding. Horses also might have rudimentary wolf teeth (first premolars), left over from a time when the horse’s jaw was shaped more like a goat or deer.
Your horse’s incisors and molars are separated by a large gap, called the “bar.” Upper and lower canine teeth might be present in that gap. Canine teeth, often absent in mares, once served as “fighting teeth” to help a stallion protect his herd. Canine teeth have very little function today.
[MORE: ROUTINE EQUINE DENTAL EXAM]
Keep in mind the following facts when considering the pros and cons of treatment trends in equine dentistry.
- Enamel can’t repair itself. The cells that form enamel (called ameloblasts) die when the tooth erupts through the jaw. This means that enamel is a “dead tissue” that can’t repair itself when damaged.
- Teeth lose enamel. Overall enamel content decreases with time and wear. Horses over 25 years old might have no enamel left at all; their teeth are composed entirely of cementum and dentin.
- Dentin can be sensitive. Dentin at the teeth’s occlusal surface is insensitive to allow your horse to chew without experiencing pain. However, dentin below the surface is sensitive.
- All cheek teeth grind food. Other than the wolf teeth (first premolars), all cheek teeth have a grinding function. If present, wolf teeth are often removed to avoid bit problems.
- The pulp cavity can be near the surface. The pulp cavity of the canine teeth can extend to a point within five millimeters of the occlusal surface.
- The pulp cavity needs normal chewing pressure. The pulp cavity—which is larger in young horses and becomes smaller over time—continuously fills with excess dentin in response to chewing pressure. If a tooth doesn’t experience normal chewing pressure, it might not have a well-filled pulp cavity. A large hook or abnormal wear can negatively affect chewing pressure.
7 Myths: Busted
Armed with this knowledge about your horse’s teeth, let’s explore the most common myths you’re likely to hear about equine dental care.
Myth #1: Veterinarians don’t know anything about dentistry. It’s much better to have an equine dentist who only works on teeth.
Tooth truth: Although it’s true that dentistry was a neglected field of study in veterinary medicine for many years, current advancements have changed all of that—especially after severe problems with the teeth started showing up as a result of overly aggressive dental work in recent decades.
Today, vets who perform dental work are highly trained, educated about sedation, and able to perform dental extractions and surgery. Unlike an unlicensed dental practitioner, your vet has a license that requires a certain amount of schooling to obtain and continuing education to maintain. Your vet also carries liability insurance to protect both you and your horse should something go wrong.
Myth #2: Power tools are a terrible thing. They make it easy for the dentist to remove way too much tooth, and create a lot of heat that can cause severe damage. Further, it’s ridiculous to sedate a horse for dental work. A good dentist can do a great job with hand tools on a well-behaved horse.
Tooth truth: When it comes to over-floating, it’s not the power tools that are a problem, it’s the practitioner. In fact, in skilled hands, power tools allow the practitioner to make necessary corrections rapidly and efficiently—making things much easier for your horse (not to mention your vet!). A well-trained dental practitioner will use sharp, clean tools, and pay close attention to time spent grinding to minimize risk of heat damage. And it’s just as possible for overly aggressive dentistry to be performed with hand tools as with power tools.
As far as sedation goes—while it may be possible to file down sharp points on an unsedated horse, there’s just no way to perform a thorough dental exam safely without a speculum and sedation. Your vet will carefully
examine every corner of your horse’s mouth using a dental mirror or even an oral endoscope. Don’t fool yourself. If you can’t see what the practitioner is doing inside your horse’s mouth, chances are, things are being missed.
Myth #3: Transverse ridges that develop side-to-side on the surface of the molars should all be filed down until they’re smooth to allow the jaws to slide freely back and forth.
Tooth truth: The surface of your horse’s teeth should be uneven with enamel ridges extending above the surrounding dentin in order for them to grind efficiently. And remember, enamel is a “dead tissue” that can’t repair itself when damaged. If the enamel ridges are filed down “smooth,” not only will your horse lose his ability to grind effectively, he’ll lose precious enamel that can’t be replaced. Finally, the ridges that develop from side to side along the surface of the molars actually help direct food that’s being chewed efficiently through the circular chewing cycle of your horse’s jaws. In general, it’s best to leave as much of the occlusal surface intact as possible.
Myth #4: If your horse gets very sore after dental work, it’s because of pain in his temperomandibular joint (or TMJ, the joint connecting the lower jaw to the skull) from holding his mouth open for a long time.
Tooth truth: Although TMJ pain is possible, the more likely explanation for your horse becoming sore after dental work is over-floating. Remember that although the dentin at the occlusal surface of the teeth is insensitive, it becomes sensitive below the surface. If the occlusal surface is filed away excessively, this sensitive dentin will be exposed, causing your horse to experience pain when he chews that can last for days or even weeks.
Myth #5: If your veterinarian doesn’t do a “performance float,” he probably doesn’t understand your show horse’s needs. A performance horse should have a deep “bit seat” that gives the bit a comfortable place to rest in the mouth. Your vet should also file down your horse’s canine teeth so they won’t cut your hand when you put on the bridle.
Tooth truth: A performance horse should have the same type of dentistry that’s done on any other horse. In fact, experts believe the term “performance float” is often no more than an excuse for excessive floating, which can be detrimental to a horse’s tooth health.
Creating a bit seat refers to rounding off the front of the premolars on both the upper and lower jaws, in theory to provide a comfortable place for the bit to rest in the mouth. Studies show that a properly fitted bit will naturally rest in the bars of the mouth; the bit is only drawn up to the teeth by the horse’s tongue as a form of resistance. A small amount of rounding can help minimize this resistance; however, an extreme bit seat requires removing an excessive amount of tooth, which can expose the pulp cavity and even lead to early tooth loss.
And while it might be “convenient” to have your horse’s canine teeth filed down to nubs, remember that the pulp cavity can be as close as five millimeters from their tip, which can lead to painful and damaging exposure.
Myth #6: Dental irregularities, such as large hooks or “steps,” develop when a horse’s teeth don’t come together properly. These irregularities can be due to abnormal jaw structure, missing teeth, or abnormal chewing patterns and should be completely corrected as soon as they’re identified. Otherwise, they’ll just get bigger over time.
Tooth truth: It’s true that these irregularities commonly develop secondary to some kind of abnormal tooth alignment, but they might not be identified until they’re very large. Remember that the pulp cavity fills with dentin in response to normal pressures during chewing, and that teeth that don’t experience normal pressures might not have a healthy pulp cavity. This makes them especially sensitive, and rapid or excessive correction is likely to cause damage. If your horse has a very large hook, step, or other significant dental abnormality, your vet is likely to recommend a gradual adjustment. He might suggest sequential appointments as often as every three to four months to safely correct the problem without damaging the teeth.
Myth #7: There’s a set of “correct” features of the horse’s mouth that should be present in every horse. The occlusal surface should be at a 15-degree angle on both sides, and the incisors should meet in a straight line. If the horse has an uneven bite, these angles should be corrected.
Tooth truth: While a 15-degree molar occlusal angle and straight incisors might be ideal—not every horse is perfect. And if these criteria aren’t met because of a structural alteration of the skull or jaw, it might be best to leave your horse’s teeth alone. Similar to how the farrier shouldn’t always “correct” the feet of a horse with crooked legs, the dentist might be better off leaving the tooth angles alone in a horse with an asymmetrical skull or jaws. If corrections need to be made, they should be done gradually to minimize discomfort and preserve sensitive teeth.
The bottom line? Over the past three decades, the pendulum in equine dentistry has swung toward aggressive dental corrections—and back again—for good reason. When it comes to the care of your horse’s teeth, less is often more.