Many of us are aware that horses and ponies require routine dental care each year, but taking time to consider the horse’s anatomy and tooth growth can shed a huge amount of light on equine dentistry. Horses are ‘flight’ animals and as such are very good at hiding pain and may only show signs of mouth or tooth pain when disease is severe. The adage ‘no pain, look again’ is one that the profession regularly quotes!
The horse is a hypsodont animal which means that the teeth continually erupt throughout the horse’s lifetime, usually ‘growing’ an average of 2-3 mm annually. This is countered by a continual reduction as the teeth are ground down whilst eating grass and fibrous forage, similar to rabbit and cow cheek teeth.
There are 6 upper and 6 lower incisors. The incisors are simple teeth and these have a single pulp horn (sensitive part of the tooth) and an enamel cup called an infundibulum. Wearing down of these incisors over time, allows us to give an approximate estimation of age, although there are huge breed and individual variations in this, meaning aging of horses is a very imprecise science. Although the incisors are important for selecting and taking in food, their lips are surprisingly mobile and also have huge importance for eating. Horses can thrive with no incisors at all!
Although we can only see the incisors, the cheek teeth are viewed as more important for chewing food prior to digestion. The mouth is divided into four arcades; upper right, upper left, lower left and lower right. Each arcade has 3 premolars and 3 molars, meaning a total of 12 upper and 12 lower cheek teeth. The teeth in each arcade are very tightly apposed together so they can act as a single unit when chewing. Cheek teeth are large, rectangular shaped teeth with multiple pulp horns. The upper teeth also have two infundibula which are blind-ending enamel cups providing added strength to the tooth.
The upper cheek teeth are wider-set than the lower cheek teeth. When the horse chews, the teeth move in a figure-of-eight action, grinding food into small digestible pieces. The chewing motion wears the teeth height down; however, due to the anatomy of the mouth and the eruption of the teeth, sharp enamel points can form on the outside (buccal) edge of the upper teeth and the tongue (lingual) side of the lower teeth. Occasionally, horses will be seen to only chew on one side of the mouth and in these cases, horses should have a full oral examination to identify any pathology or problems before they become severe.
Images in order: Oral examination under sedation using light source and mirror, Infundibular restoration (filling) of caries, peripheral caries, oroscopic examination of teeth and oral soft tissues, tongue ulceration.
The oral examination
A full oral examination should be undertaken at least annually. Even if the horse does not require any routine rasping, the examination will detect any abnormalities of the teeth and the soft tissues in the oral cavity. A complete oral examination can only be undertaken when a horse has a full mouth speculum in place, an appropriate light source and using an angled mirror. For a more comprehensive examination, the horse should be sedated so all areas can be examined. An oroscope or oral camera can be used to visualise the teeth, the space between the teeth and tooth surfaces. Oroscopes also allow us to capture images of the mouth and monitor any progression of problems. It is surprisingly difficult to assess a horse’s mouth even if they are very lightly chewing or moving their tongue.
When examining the horse’s teeth, although we predominantly focus on the teeth, complete examination of the soft tissues including the cheeks, the gum-tooth margin, the palate and the tongue can provide vital clues to the horse’s oral health.
Common problems we identify include:
Sharp enamel points on the cheek (buccal) side of the upper teeth and the lingual (tongue) side of the lower teeth.
Focalised overgrowths, particularly on the first and last cheek teeth
Increased or reduced table height of the teeth
Diastemata (gaps) between the teeth
Ulceration of the cheeks or tongue
Abnormalities of the teeth surface, including caries or open pulp horns
Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH)
Incisors and canines
Images in order: Incisors, A geriatric incisor with discharging tract above suggesting disease, cheek teeth of a geriatric pony with multiple problems
Routine annual treatment of enamel points involves rasping or floating the teeth in order to prevent any sharp areas causing trauma to the surrounding tissues. This can be done by hand rasping or mechanised floats.
If using an equine dental technician (EDT), we would always suggest using an EDT that is qualified and registered with the British Association of Equine Dental Technicians (BAEDT) which is a professional body of individuals who have been rigorously examined by British Equine Veterinary Association (BEVA) and the British Veterinary Dental Association and have appropriate insurance and a code of conduct. Category 2 members of the World Wide Association of Equine Dentists (WWAED) also hold a qualification recognised by BEVA. Appropriately qualified EDTs are allowed to undertake ‘Schedule 2’ procedures which includes palliative rasping and removal of wolf teeth under direct and continuous veterinary supervision.
Veterinary surgeons have the ability to use sedation and are licensed to undertake all procedures from routine reduction of sharp enamel points, use of motorised dental instruments through to the diagnosis and treatment of diseases of the teeth and oral cavity. More advanced dental procedures are usually undertaken by veterinary surgeons that have appropriate extra training in dentistry.