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Equine dentistry and modern techniques used in the treatment of dental disease
Any discussions on equine dental techniques must start with a basic explanation into the evolution of the modern horse. The horse evolved in Central and South America some 55 million years ago and was adapted to live on a diet of soft highly nutritious leaves. Due to climatic changes in the Americas much vegetation changed to coarse grasses and the prehistoric horse evolved a new dentition to cope with this, its teeth becoming long crowned and erupting continuously over the 20-25 years of the animal's life.
It is therefore obvious that the modern horse has a highly evolved dentition which is extremely important to its overall health and well-being. In recent years our understanding of dental diseases and how they affect the health and welfare of your horse has improved greatly along with the techniques and equipment we use to treat them. At Three Counties Equine Hospital we have invested greatly not only in the modern diagnostic equipment such as radiography, endoscopy and scintigraphy, required to investigate dental diseases but also in the training of our veterinary surgeons in modern treatment techniques.
When discussing signs of dental disease in the horse it is important to emphasise that many animals will suffer silently from severe and painful conditions without showing any outward signs. It is therefore important that a thorough dental examination be performed regularly on all horses.
The frequency of routine dental examination and rasping should vary according to the age and work of the horse. At 2-5 years of age horses are shedding teeth and should have regular 6 monthly examinations. Likewise elite competition horses, which need to respond optimally to subtle messages from the rider through tack, will also need special attention. In contrast a brood mare or a retired pony with normal dentition would only require examination every 12 months.
By the time that signs of oral pain are exhibited the dental disease processes are usually quite advanced. Obvious signs include quidding (dropping of partially chewed food), pouching of food material in the cheeks and weight loss. Common presentations which may be first noted by an owner are bitting or head carriage problems. This can go on to cause secondary neck and back problems.
The normal horse has six cheek teeth in each arcade acting together as a single functional unit which is highly efficient at grinding fibrous food material.
A common and very painful condition can occur whereby gaps develop between the adjacent cheek teeth. The constant high pressure grinding of fibrous material will eventually trap food fibre between the teeth. These fibres get pushed further down into the periodontal spaces causing irritation and damage to the very sensitive tissues and thus causing great discomfort. These gaps (or diastema) between cheek teeth are an under-diagnosed dental problem and require careful and professional examination to be diagnosed.
In the short term this condition can be managed by putting the horse onto a short fibre grass diet. The softer smaller grass fibres are not so easily trapped in the sensitive periodontal spaces. The best long term treatment however is to use specialised dental burrs to open or widen the gaps. This procedure must be performed with great care so as not to permanently damage the sensitive tissue within the tooth. As such this is a specialised technique which should only be performed by a veterinary surgeon.
Another serious and painful condition to consider is the tooth root abscess. Clinical signs of infection depend on which tooth is involved. Problems within the lower arcades will lead to a painful hard swelling along the lower jaw which can develop a purulent discharge. Infections of the upper arcades can be more complicated causing secondary infections of the associated sinuses and can present as a smelly, purulent one-sided nasal discharge.
There are many causes of sinusitis and nasal discharge other then dental disease and as such we use a number of diagnostic techniques to investigate these cases.
Nasal endoscopy where a fibre optic camera is placed up the nostril allows us to view where the discharge is originating from. Radiography (xrays) enables us to see infection within the sinus and also to assess the tooth roots. Direct sinuscopy is where we create a small opening into the sinus allowing the introduction of a flexible endoscope. This then gives a direct view of the interior of the sinus.
Another valuable technique we have available is nuclear scintigraphy, where a hot spot (increased radionucleotide uptake) is shown around a single root indicating infection. This is especially useful when other conventional diagnostic techniques have failed to indicate the source of the infection. After we have used these techniques to confidently isolate the source of the infection we can focus our efforts on treating the problem. With tooth root abscesses this usually requires extraction of the tooth. In conclusion it is important to remember that regular veterinary examination of your horse’s mouth can correct or hopefully prevent the conditions described.
Most modern equine hospitals will have the facilities, equipment and expertise to diagnose and treat overt dental disease but also help prevent problems therefore optimising your horse’s performance and welfare.
J Campbell, BVMS, MRCVS
(This article appeared in April / May 2009 of Central Horse News.)