Nixon Equine Dental Services

Periodontal developments

As a progressive veterinary practice, Nixon Equine is committed to keeping abreast of the latest techniques as part of its continuing practitioner development (CPD) policy. Equine dentistry is evolving at a rapid rate and to aid us applying the new knowledge and techniques we have purchased an Equine Periodontal Unit from the US. This new equipment is the ultimate system for the treatment of equine periodontal disease. We also work with an advanced equine dental technician who uses the new dental techniques under veterinary guidance. Simply rasping sharp edges and reducing hooks is no longer sufficient! Proper dental care is needed. One of the major causes of tooth loss in equines is advanced periodontal gum disease and infundibular necrosis.

Equine dental treatment

Preventing premature tooth loss and decay is less expensive than the eventual cost and risk of oral extraction and ongoing expense of a specialised diet of an equine missing one or more cheek teeth. Help is at hand... Our new Equine Periodontal Unit provides comprehensive protection and dental care for your horse, including cleaning out debris and filling cavities. Other benefits include:

* Much improved performance
* Hygienic treatment stops toot decay
* Happier horse that utilises food better
* Maintains the horse’s teeth long-term.
Pictured right, Jane Nixon with her own horse Diamond King II undergoing treatment with the Equine Periodontal System.

Dental evaluation and routine treatment

Horse's teeth should be examined every 6 months by a veterinary surgeon experienced in the equine dental arcade or by a trained equine dental technician. Nixon Equine undertake routine rasping of normal, well-bahaved. horse's mouths and minor correctional changes of alignment: points or small hooks capable of rasping down, at client stables within a 30 mile radius of the Maids Moreton, Buckingham equine clinic, within Bucks, Beds, Oxon and Northants.

Dental treatment at the equine clinic

Horses needing major correction or realignment requiring intensive work essential to optimise performance or welfare, are admitted as equine out-patients to our purpose built equine clinic. Treatment is undertaken with the horse under sedation, in stocks on a non-slip rubber floor, using an open mouth speculum, a very bright light and a padded bar for support. Approximately 5% of all horses examined require more sophisticated dental treatment inour experience.

Improvement in referred cases

We often see cases where horses were pronounced normal by so-called "equine dentists" that in fact have hooks or unopposed molar teeth which dig into the opposite gum. Following treatment many cases show improved food conversion, weight gain and produce normal faeces where previously they had diarrhoea. Improved gut function also helps horses that may be excitable and stressed by competition. Striking results have been seen with head carriage, with clients reporting improved bit acceptance and a more forward going action within 6 weeks.

Management following dental treatment

After treatment allow pre-existing sores to heal. Use a loose-ring jointed snaffle and loose cavesson nose-band. Ask the horse to go forward from behind. Do not take a contact until the horse asks you. It may take 6 weeks for the jaw joint to settle after realignment, for back pain to ease and for the horse to regain confidence after its previously painful experience.

The horse's mouth structure and function

A horse's mouth comprises: incisors, tushes, premolars (including wolf teeth), molars, hard palate, soft palate, bars, tongue and frenulum. See Diagram 1 left.

Incisors

The function of incisors is to cut grass at ground level. The normal horse's upper jaw when standing, but not eating or chewing, will appear to be approximately 2 mm overshot (protruding over the lower jaw). As the horse's head descends to the floor to eat, the lower jaw comes forward underneath the upper jaw, and when the horse is eating the incisor teeth are in exact apposition (the teeth of the upper and lower jaws meet exactly). See Incisor Diagrams 2-5 left.

Tushes

The tushes are vestigial tusks. They appear, protruding through the bars in both upper and lower jaws, from a few months of age. They are of no functional use to the horse but if they become large or grow at an angle will press into the tongue or the cheek. If the tushes are slow to erupt, the bit can press on the gum over the tush, which will cause the horse pain.

Premolars and molars

Molars extend along the upper and lower jaws of the horse to just behind the level of the eye. The first premolar is a wolf tooth which is a small tooth usually on the top jaw.

Hard and soft palate

The hard palate is the roof of the mouth extending from the incisors to approximately the last molar and the soft palate is the back of the roof of the mouth which is soft and flexible.

Bars, tongue and frenulum

The bars are the areas of gum which overlie the bone between the molars and incisors, this is extremely sensitive gum and very easily damaged. The tongue is a large muscular organ which moves food together with the chewing action of the molars, from the front to the back of the mouth. During this process the fibre length of the food becomes progressively shorter prior to it being swallowed. The tongue is attached to the base of the mouth by a membrane called the frenulum which helps keeps the tongue in place and is extremely delicate. The tongue must always be handled very gently in order not to damage the frenulum.

Jaw movement

The lower jaw moves forwards as the horse puts its head to the floor and bites grass. The lower jaw also moves from side-to-side as food is masticated and passed to the back of the mouth. This forwards and sideways movement of the jaw is known as an excursion. In order for a horse to optimise its food intake, the jaw excursion should be maximal and uninterrupted. If the distance moved left and right is not the same, or the distance moved is less than a 1.5 incisor width, then there is an abnormality in that horse's mouth which requires attention.

Changes with age

A horse's milk (or deciduous) teeth are replaced by permanent teeth by the time they are five years old. The teeth all grow until about six years old. The crowns are worn away, particularly the molars, through abrasion against the teeth on the opposite jaw. Thus the young horse has a much larger reserve molar crown than the older horse. The incisors, which have relatively long crowns, do not continue to erupt to the same extent as the molars. Consequently wear with age lowers the amount of crown, even to the gum in the very old horse. Unlike the molar they rarely fall out. The tushes which are never in contact above and below do not wear out.

Conformation

Purebred horses show better conformation of the lower molar dental arcade fitting with the upper dental arcade than crossbred horses. Crossbres are more likely to have aberrant dental arcades with regard to the width, length and contours of the top and bottom jaws. The angle of the head on the neck also makes a difference as to the fitting of the lower jaw to the upper jaw.

Bit seats

A "bit seat" is created so the bit can fit comfortably in the horse's mouth whilst "three-point balance" is maintained. This enables the horse to go forward in "self-carriage" with no restriction imposed by the dental arcade. If the horse is uncomfortable in its mouth it may hold its head abnormally on its neck. This in turn makes the horse stiff through the back, may well alter its gait, reduce athletic performance and eventually cause lameness. If this abnormal head carriage continues for any length of time the musculature of the horse's neck, trunk and limbs will re-adjust and no longer be symmetrical between one side of the body and the other. This is the start of a vicious circle of a one-sided and possibly lame horse. Bit seats are produced by optimising the three-point balance, removing wolf teeth and fashioning the second premolars.

Three point balance

Three-point balance refers to the correct function of 1) the incisors 2) the molars and 3) the mandibular (jaw) joint. Three-point balance facilitates normal jaw movement and is achieved by removal of hooks and sharp points, which develop on the outside of the upper and inside of the lower premolars and molars, and adjusting the line of the incisors.

Changes to the dental arcade with ageing

With the back and forwards movement of the lower jaw, hooks may develop on the second upper premolar which inhibit the forward movement of the lower jaw against the upper jaw. As a result of inhibited movement the furthest back molar on the lower jaw will also develop a hook which will then also prevent the lower jaw moving forwards. See Diagrams 6-9 left.

Skull overbite and hooks

With age the incisors become out of alignment and the upper jaw overshoots the lower jaw.

Skull underbite and ramps

Age related developing hooks should be removed and teeth re-aligned or the condition will progressively worsen. The movement of the lower jaw against the upper jaw in a back and forward motion will be lost. Furthermore the molar hooks may dig into the gums of the respective lower and upper jaws, causing pain and prevening acceptance of the bit.

Molar spurs

Side-to-side grinding of the molars causes development of spurs on the outside of the top molars and inside of the bottom molars. In time this prevents the jaw moving sideways properly and also causes painful points which can ulcerate the tongue and insides of the cheeks.

Unopposed teeth

If a horse loses an incisor or molar the tooth on the opposite jaw will erupt unworn into the gap sufficiently to pierce the gum and stop the back and forwards or side-to-side jaw excursion. It only requires one tooth or hook to be out of alignment to completely wreck the normal range of jaw movement. To optimise food conversion the horse must exhibit normal front-to-back and side-to-side jaw excursion. Hooks and unopposed teeth should be surgically reduced by a veterinary surgeon using power instruments while the horse is sedated. See Diagram 10 left.

Wolfteeth

We recommend that wolf teeth be removed. Most of them are likely to cause problems and will reduce a horse's performance. The wolf teeth are the first premolars, normally only apparent in the upper jaw, but they can sometimes occur in the lower jaw. They are present at birth and can erupt at any time from a yearling onwards, and can vary in size from 1 mm to 1cm in length. They can be apparent for up to two centimetres in front of the second premolar, but more often are adjacent to it. They can be of particular annoyance to the horse when they are on the inside and close to the front of the second premolar. Many wolf teeth are missed because they are very small, the same colour as the premolar and are impacted against the inside of the premolar which makes them difficult to see. Regrettably, people who are not trained veterinarians sometimes attempt to remove wolf teeth, resulting in roots being left behind. The gum then grows over the root, causing the same effect as a small wolf tooth. Under these circumstances the veterinarian will x-ray the horse's jaw to determine if a root is present or not.

Correction realignment and The Veterinary Surgeon's Act

It is currently legal for a lay person to rasp a horse's teeth. However, it is illegal for a lay person to perform any other dental manipulation, such as extraction, or to administer sedative drugs. Many so-called "equine dentists" have no formal training. In addition, it is illegal for a person other than a qualified human dentist to use the term 'dentist'. There are many cases in which equine welfare has been severely compromised by the practises of so-called "equine dentists". In some cases the horse's life has been jeopardised. Nevertheless, it is recognised that there is a minority of people who have received good training in the United States and can perform competent jobs. It is currently illegal for any person, whether or not they have attended such a course, to perform any form of dental manipulation other than to rasp a horse's teeth with physical restraint of the horse, or with sedation provided by a veterinary surgeon if necessary. Any tooth root abnormality is detected by the use of X-Ray. Endoscopy is also used for the examination of interdental space problems and dental caries. This work can only be performed at our surgery under these conditions.

24 hour equine veterinary emergency telephone: 01280 813258.