The Basics

Equine dentistry can be one of the most challenging and rewarding aspects of veterinary medicine.  These days many veterinarians have special training in dentistry and several have devoted their practice exclusively to the subject.  As an associate at McKee-Pownall Equine Services I perform a variety of services on a daily basis but dentistry has always been area of special interest to me.  You never know what you are going to find when you look into a horse’s mouth…and it’s a great upper body workout!

All horses regardless of their age, size and use benefit from regular dental care.  They have a set length of reserve tooth crown in their jaw.  The adult teeth erupt continuously over their lifetime and are ground down through the action of chewing.  Due to the conformation of their jaws (upper is wider than lower) they form sharp enamel points on the cheek side of the upper cheek teeth and the tongue side of the lower cheek teeth.  These are the areas of the dental arcade that never contact the opposing arcade during the chewing stroke and therefore don’t get ground down naturally.  Left as is, these sharp points can cut into the cheeks and tongue causing painful sores that bother the horse when it is chewing or wearing a bridle.  Sharp enamel points are a normal finding that must be maintained in all horses.  Basically, in the routine mouth we go in and grind off the part of the tooth that the horse can’t take off himself.  However, in addition to sharp enamel points many horses have actual dental pathologies and can suffer much more serious consequences without dental care.  I will go into some of the most common problems in this blog.  In order to remove the sharp points and identify additional problems every horse should have a full dental exam once a year.  A proper exam includes sedation and a full mouth speculum.  The speculum holds the horse’s mouth open and allows the veterinarian to visualize the entire mouth, feel problem areas and use mirrors or other tools to complete a thorough exam.  The sedation ensures that the horse is cooperative, relaxes their jaw for speculum placement and helps alleviate any fear or nervousness.  It also increases the safety for the horse, handler and veterinarian.

Dental prophylaxis is aimed at removing the normal sharp points and dealing with any additional problems that prevent the jaw from functioning properly.  Malocclusions are conditions that cause abnormal contact between opposing teeth.  They can cause problems for the horse by restricting normal jaw motion or by applying abnormal forces on the individual teeth.  Horses chew their food in a side-to-side (lateral) grinding motion.  In addition when they raise and lower their head the jaws move in a front to back (rostrocaudal) motion.  The incisors meet optimally when the head is down in the grazing position.  Any malocclusion that prevents either of these motions can cause discomfort for the horse, reduce grazing and chewing efficiency, and restrict their ability to carry a frame under saddle.  When abnormal forces are applied to individual teeth periodontal pockets can form or weakened teeth can fracture.  The pockets form at the gum line, are very painful and can become quite deep when feed packs into them.  Left untreated they can lead to deep infections and abscesses.  In severe cases the tooth can be compromised enough to require extraction.  Fractured teeth are also painful, open the root up to infection and require extraction.

Some of the most common malocclusions are hooks, steps, waves and excessive transverse ridges.

Hooks occur most commonly on the front edge of the first upper cheek teeth and/or the back edge of the last lower cheek teeth.  They look like the tooth has grown too long  (when actually as we have learned they just haven’t been ground down).  As they get bigger they block the rostrocaudal motion effectively “locking” the jaw as the horse raises and lowers its head.

Steps can occur on any tooth.  The entire tooth is not ground down and is therefore extra long.  This usually happens when the opposite tooth is missing and will block jaw mobility when the step fits into the gap on the opposite arcade.

Waves can affect the entire dental arcade and have low and high spots that usually mirror the opposite arcade.  They can restrict motion and apply abnormal forces on individual teeth.

Transverse ridges are part of the normal anatomy of the grinding surface and increase chewing efficiency and surface area.  Excessive transverse ridges can occur on one or several teeth and look like an exaggerated washboard on the normal occlusal surface.  Think of 2 washboards locking together and you can imagine the effect these have on that rostrocaudal motion.

This was an overview of the basics of equine dentistry.  Overall it is a complex and extensive topic.  Going forward I will cover specific topics in greater detail and discuss some of the interesting cases we see in our practice.  If there is a dentistry topic that you would like to know more about please let us know and I will do my best to put something together.  My next blog will discuss the special dentistry needs of the Miniature Horse.

Dr. Michelle Courtemanche

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