Kieran O'Brien MVB PhD MRCVS
EqWest Equine Veterinary Clinic, Lamerton, Tavistock, Devon
Tel. 01822 613838

Lets start with a few key facts

  • Horses don't die of old age. At some stage a decision is made to painlessly end their lives often because they have developed progressive arthritis or because they are having difficulty keeping in good body condition because of dental problems. The latter are largely preventable if the teeth are regularly attended to, but this attention must start in early adulthood
  • Teeth problems are very common in horses but the majority suffer in silence until their tolerance level is passed. Then symptoms such as resentment of the bit, abnormal head carriage, loss of suppleness, and back problems start to appear
  • True quidding, involving expulsion of plugs of partially chewed hay -not grass or hard feed- is quite rare and always reflects serious dental disease. More commonly horses with dental problems masticate food less efficiently and although they may not appear to be thin, these horses are wasting feed.

    What goes wrong?

    The horse's head is essentially a huge chewing machine. While the incisor teeth at the front help the horse to graze, the 24 cheek teeth occupying most of a horse's head do the real work. A horse spends about 60% of the day eating, and will chew 15-25,000 times when consuming a 5kg net of hay, reducing the long stems to very short 2-5mm lengths before swallowing.

    This amount of chewing causes enormous wear to the surface of the teeth but equine teeth, unlike ours, continue to erupt until horses are about 25 years old such that the rate of eruption matches the rate of wear. Equine teeth have in addition a very clever self-sharpening mechanism as they wear in that the softer dentine component of the teeth wears at a greater rate than the harder enamel, thereby progressively exposing narrow enamel ridges and ensuring that a rough surface remains.

    But there is a design fault in horse's heads. The lower jaw is narrower from side to side in comparison with the upper such that the upper and corresponding lower teeth do not cover each other exactly. Consequently hard, unworn, enamel spikes develop where the upper and lower teeth do not make contact. In addition the chewing of hard feed requires must less side-to-side movement of the lower jaw than hay, accentuating the lack of wear.

Diet Grass/Hay Oats Chaff
Sideways movement of the jaw (mm) 60 38 23

So it follows that horses on relatively 'unnatural' diets (hard feed and restricted hay) suffer much more from sharp unworn teeth than say, moorland ponies on a sole diet of rough herbage.

Jaw movement

In addition to the side-to-side chewing action, the jawbone also alters position as the position of the head in relation to the neck changes. With the head elevated the jaw retracts, and conversely when the poll is flexed the lower jaw moves forwards. Any restriction of this forward movement, predominantly caused by enamel 'hooks' on the first upper and last lower cheek teeth jamming against the corresponding over- or underlying tooth, will make it very difficult for the horse to adopt the poll flexed 'dressage' posture unless it opens its mouth. This mouth-open posture is perceived as a 'resistance' and invariably prompts the trainer or rider to tighten the noseband. The horse consequently is in constant discomfort resulting in tension in the neck and ultimately in a back problem.

Bit comfort

Horses in discomfort from the bit will show resistance when the rider takes up a contact with the reins. This resistance may involve raising the head, trying to pull the reins from the rider's hands, showing reluctance to come down on the bit, being 'stiff' on one rein, jumping to one side of the jump etc. Some hard-pulling horses are running away from the discomfort caused by the bit. Any horse that shows resistance when ridden should have its mouth carefully examined. Most dental problems are easily fixed, often resulting in a dramatic improvement in the horse's acceptance of the bit

In addition to causing pressure on the tongue and bars, the bit pushes the soft tissues of the cheeks against the cheek teeth. Wolf teeth are variable-sized 'extra' teeth found in 30-50% of horses just in front of the first upper cheek tooth, exactly where these soft tissues are pushed by the bit. As discomfort is likely, removal is strongly advised.

As a further aid to bitting comfort we often also reshape the leading edges of the first upper and lower cheek teeth (see diagram) to create more room for the cheek soft tissues. This reshaping is called creating a bit seat, and may dramatically alter the comfort level of a bitted horse, causing relaxation of the poll and better acceptance of the bit.

Solving dental problems

The last cheek teeth erupt at four years of age. By five years the abnormal wear has started to begin so it follows therefore we at EqWest Equine Clinic recommend that every horse five years and older has its teeth checked at least annually. If done regularly only minor attention is normally all that is required. Sharp enamel points are removed with a selection of rasps, although occasionally motorised grinding equipment is required for more extensive abnormalities.

For adequate examination of the teeth it is essential that a full mouth gag be used. This allows the vet to see and feel every single tooth, and the tissues of the mouth, to detect any problems that need correction. More importantly the vet can also choose the appropriate equipment for each abnormality and especially conform at the end that the problem has been solved. Good dental care requires lots of experience and an extensive range of equipment, found principally in specialist equine veterinary practices. If you use a dental technician make sure they are on the BEVA/British Veterinary Dental Association's Approved list - many are not !

When were your horse's teeth last checked? Is he/she suffering in silence?


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