Priors Farm: Equine Veterinary Surgery in Sussex

Dentistry in horses has undergone a revolution in the past few years. Traditionally, your vet would have been consulted if you had a concern regarding teeth. However, equine dental technicians have for some owners become the first port of call if there is a suspected problem with a horse's teeth.

How often should my horse's teeth be examined?
Your horse's teeth should be examined at a minimum period of every 12 months, though some horses need to be examined every 6 months. This allows problems to be identified quickly before they cause any discomfort.

Why do my horse's teeth need to be floated (rasped)?
Horses have evolved to graze grass for up to 18 hours a day and their teeth are specially adapted to chew grass for this length of time. A horse's teeth continue to erupt for most of its life and therefore the teeth need to be worn down to prevent them overgrowing. The chewing action results in the upper and lower teeth grinding against each other and this action will wear down the teeth keeping the crown of the tooth (the bit above the gum line) at the correct height. If the horse does not chew for long enough, then the teeth may not be worn down enough.

The side to side movement of the jaw when chewing is also vital in correctly wearing down the teeth. The greater the lateral movement, the better the teeth will be worn down. Grazing grass will result in the greatest degree of lateral movement, followed by forage feeds (hay, haylage and straw). Short feeds result in very little lateral movement of the jaw while chewing.

Horses come in all shapes and sizes and the variation has happened relatively recently. Each horse breed has been developed for a particular purpose; obviously the Thoroughbred has been specifically bred for racing, while the Shire has been bred for pulling carts. Genetics play a vital role in determining the shape and size of a horse jaw and teeth. When a foal is born, the shape and size of the jaw and teeth have been determined by both the sire and the dam. Unfortunately, nature rarely averages out the differences between the shape and size of the sire's and dam's jaw and teeth. Simply put, if you breed a large headed sire whose teeth are large with a small headed dam whose teeth are small you will not necessarily get a foal with a medium sized head with medium sized teeth. Sometimes you get a large head with small teeth and sometimes you get a small head with large teeth and all the combinations between! If the jaw size and teeth size do not match, then the teeth will not wear down correctly when chewing.

So one can now see that there are three determining factors that influence whether a horse's teeth are worn down correctly: the length of time spent chewing, the type of feed being chewed and the size and shape match of the teeth and jaw. If any or all of these factors are removed from the ideal then the horse's teeth are not worn down correctly. This will result in the edges of teeth becoming sharp and, in some cases, overgrowth of the crowns.

Which part of the teeth is routinely floated?
The way in which a horses teeth and jaw are aligned and the manner in which it chews result (if the three determining factors are not ideal - see above) in the outside of the teeth of the upper jaw and the inside of the teeth of the lower jaw becoming sharp. It is these sharp edges that are smoothed when your horse has its teeth routinely ‘floated’. Please see the glossary below for an explanation of the terms used in this table.

What other abnormalities are found in horses mouth?

Abnormality	Definition	Cause	Resulting Problems	Solution
Caudal hooks	Lower or upper last cheek tooth overhanging the opposing cheek tooth	Hereditary – may result from horse born with under or overbite. Developmental – may result secondary to cheek tooth malocclusion that forces jaws out of alignment.	Prevents horse from chewing side to side resulting in improper and excessive molar wear. The cheeks and gums (soft tissues) are very susceptible to lacerations from sharp points. This condition may cause extreme discomfort when head carriage or frame is changed during ridden exercise.	Reduce dominant cheek tooth to prevent excessive wear to opposing cheek tooth and carefully round to prevent soft tissue trauma.
Rostral hooks	Upper first cheek teeth overhang opposing cheek teeth.	Hereditary – may result from horse with an overbite Developmental- may result secondary to cheek tooth malocclusion that forces jaws out of alignment	Prevents horse from chewing freely from side to side resulting in improper and excessive cheek tooth wear. Hooks may cause excessive wear to opposing lower premolar, severe bit problems and trauma to soft tissues in this area.	Reduce dominant portion of upper cheek tooth and round smoothly towards the gum. Preventative maintenance required to avoid reoccurrence.
Ramps	Lower front cheek teeth higher than other teeth.	May occur when upper front baby tooth (deciduous cap) is retained preventing normal growth of permanent cheek teeth. Can occur if a tooth is reduced without corresponding correction of opposing tooth.	Prevents horse from chewing freely from side to side resulting in improper and excessive tooth wear. May cause severe discomfort with the bit or force lower jaw forward over time causing an under-bite.	Reduce dominant tooth to allow opposing tooth to recover over time.
Enamel Points	Sharp points that generally form on the outside of the upper cheek teeth and the inside of the lower cheek teeth.	Occurs over time as the horse stops complete sideways chewing. The result is the unopposed edge of tooth getting longer and the enamel form razor sharp points.	Enamel points traumatize soft tissue causing pain and discomfort when eating, from bits and other headgear pulling cheeks and tongue into these areas.	Remove sharp enamel points.
Sheared Molar table	Extreme angulation of chewing surface of cheek teeth.	Results from lack of side to side chewing.	A very severe problem as it prevents the horse from chewing sideways. The result is poor utilisation of food and may lead to chronic weight loss.	Correct angle of upper and lower molar table over time to allow side to side chewing.
Wave Complexes	Dental arcade develops "wavelike" appearance generally involving many teeth.	Often occurs secondary to other malocclusions such as retained deciduous caps, missing teeth, hooks or ramps, etc. Results from horse being unable to obtain free side to side chewing.	Causes gradual excessive wear to the teeth, resulting in prematurely worn-out teeth, periodontal (gum) pocketing, decay and loss of teeth. Inhibits side to side chewing and effective grinding of feed.	Reduce high complexes to allow recovery of opposing teeth and allow freedom to chew side to side and encourage proper use. Preventative maintenance is required gradually over time.
Stepped Molars	Dental arcade develops a step like appearance.	Most often due to a missing tooth allowing the opposing tooth to grow into the void. Can occur from extreme uneven wear, or when a deciduous cap is retained too long delaying normal growth of the permanent tooth and allowing the opposing tooth to grow too long.	Prevents or blocks the horse from being able to chew freely thus resulting in uneven wear to cheek teeth and incisors.	Reduce high cheek tooth to allow freedom to chew correctly. Requires maintenance to prevent unopposed tooth from growing into space.
Accentuated Transverse Ridges	Enlarged ridges that run across the chewing surface of the cheek teeth.	Can result in a shift in jaw alignment. A harder area in one part of the tooth will over power and wear into a softer part of an opposing tooth. Can also occur if horse is not chewing a proper side-to-side motion.	Interferes with normal chewing and jaw motion. Can cause excessive wear to opposing cheek teeth. May result in diastema formation and ongoing periodontal disease.	Reduce enlarged ridges and allow opposing teeth to recover and the horse will chew correctly. Will improve when existing malocclusions are corrected.
Periodontal pockets	Gum disease around a tooth causing an area where the feed will pocket.	Results from malocclusion and misalignment of teeth. Progresses, as horse is unable to chew correctly.	Gum disease may lead to bone erosion around teeth and ultimately infection, abscess formation and loss of the tooth.	Correct malocclusion as quickly as possible. Very difficult to stop progression of peridontal disease if it is not stopped early on. Prevention is the key.
Diastema	A space that occurs between two adjoining teeth.	Often results when malocclusion forces the teeth apart over time.	Feed may become trapped between teeth resulting in progressive and severe periodontal disease. Result in overall poor oral health.	Very difficult to correct. Reduce unopposed over grown teeth. Prevent malocclusion.

How are overgrowths, hooks and ramps corrected?
If these overgrowths are small they may be filed down by hand. However, if they are too large, then the tooth may need to be ground down with a mechanical tool. Only vets and fully qualified equine dental technicians are legally allowed to remove these overgrowths mechanically.

Glossary

Cheek teeth: These consist of three premolars at the front and three molars at the back i.e. there are six cheek teeth each side of both the upper and the lower jaw.
Incisors: The six front teeth.
Overbite: When the upper incisors project over the lower incisors.
Undershot: When the lower incisors project forward of the upper incisors.
Malocclusion: Incorrect position of teeth resulting in faulty meeting of teeth so they cannot grind effectively.
Misalignment: Incorrect position of teeth can lead to malocclusion.
Cap: Residual deciduous teeth (baby tooth) sat on top of an erupting permanent tooth.
Periodontal: The tissues around the teeth providing support including the surrounding bone, gums, and periodontal ligaments

DISCLAIMER: This advice is intended for use by registered clients of Priors Farm only. The advice offered is general advice only. Priors Farm clients who wish to discuss the individual circumstances of their horse should contact the office. To speak to a vet please phone between 8.30 - 10.00 am on weekday mornings.

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