Dentistry...
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The importance of equine dentistry
The understanding of the importance of equine dental care is vital for any person that has contact or works within the equine industry.
The aims of this section are to discuss the importance of equine dental care, how evolution and domestication have effected the equines dietary requirements and change in mastication patterns. Discuss dental problems that may occur due to breeding, injury and feeding and the indications.
There have been many changes in the equine head anatomy all through evolution; changes include going from brachydont to hypsodont (short crown teeth to long crown) teeth which have prolonged eruption throughout life. Over time horses have gone from browsers to grazers due to climate and diet changes’ studies of dental structure and wear patterns suggest that these early horses were browsers, probably feeding on soft leafy vegetation and ground cover’ (G.J Baker & J.Easley,2005). This has caused the whole system of mastication also to change. Teeth have adapted for the purpose of grazing, incisors tear the forage and the pre molars and molars grind the forage to breakdown the cellulose for correct digestion.
The changes through evolution from the short crowned hydracotherium to the long crowned Equus (G.J.Baker and J. Easley 2005).
Showing the modern equine skull and position of all the teeth within (G.J.Baker and J. Easley 2005).
Domestication means the demands on the equine have changed. Horses are now mainly used for sport and leisure purposes. As the role of the horse has change so has the diet, therefore dental formation and dental care has become more important. Today the majorities of horses are kept in stables and controlled conditions, this has led to a diet of concentrates. This means that the Incisor wear has been significantly reduced leading to an alteration in mastication patterns. The feeding of concentrates shortens the mastication cycle, therefore reducing the power stroke (where the horse grinds its feed), so shortening the contact between the two occlusal surfaces, this then causes teeth not to wear properly causing sharp enamel points to form on the buccal region of the upper cheek teeth and the lingual side of the lower cheek teeth. This can be commonly seen in sport horses as they are fed a high ratio of concentrates to forage.
This is showing the cheek teeth and their occlusal surfaces that are involved with mastication (power stroke) (G.J.Baker and J. Easley 2005).
The most common dental problems include:
- Sharp enamel points
- Misalignment malocclusions (hooks and ramps)
- Infundibulum carries or peripheral carries
- Diastemas and periodontal gum disease
- Shearmouth (excessive angulation)
- Incorrect incisor angles
- Wolf tooth discomfort
- Steps or super eruption due to missing teeth
- Retained deciduous teeth (caps)
The above problems can cause:
- Quidding (dropping feed),
- Difficulty eating and chewing,
- Head tilting
- Behaviour problems,
- Nasal discharge,
- A foul smell
- Condition Loss
- Drop in performance.
Showing the sharp enamel points that can form on the cheek teeth and also an overgrowth on the 06 (G.J.Baker and J. Easley 2005).
These sharp points can cause severe ulceration and laceration to soft tissue within the mouth which are extremely painful for the horse. This may cause them to go off their feed and may develop behavioral problems ‘secretion of enamel in the unique pattern of the maxillary and mandibular teeth results in the appearance of enamel points’ (G.J Baker, 1979)
Showing the damage that sharp enamel points can cause to the soft tissue within the mouth (G.J.Baker and J. Easley 2005).
These points should be floated as soon as they are discovered and this will also create a more even bite plane ’management should be based on attempts to restore normal occlusal contact’ (E. Becker, 1962).
Older horses can have excessively worn teeth (smooth mouth) and loose teeth frequently. This is because there is not normal contact between the occlusal surfaces so the opposite remaining tooth will overgrow and cause abnormal wear and poor alignment of the other teeth.
Foals/yearlings develop problems too during eruption of adult teeth. This can be retained caps (which are deciduous teeth) that can cause infection and abnormal alignment of the teeth as they develop.
The modern day horse can also have congenital dental problems; this can be caused by breeding from a horse that either has the condition in its genes or actually having the condition itself. Some of these conditions maybe: Brachygnathia (parrot mouth), Prognathia (sow mouth), and Campylorrhinus (wry nose). It is advisable not to breed from these sorts of horses as it can result in breathing and eating problems.
Showing a picture of Brachygnathia (G.J.Baker and J. Easley 2005)
Showing a picture of Prognathia (G.J.Baker and J. Easley 2005)
Showing a picture of a foal with Campylorrhinus (G.J.Baker and J. Easley 2005).
There are many different breeds of horse, and the smaller breeds have characteristics of a small head for example, Arabs and Welsh section A. These breeds of horses are prone to dental problems as there is a small space for a lot of teeth to erupt. ‘smaller breeds of horses, ponies and miniature horses have cheek teeth arcades that are not truly horizontal and this slight dishing becomes more obvious with age’(K.D.Kirkland,1994).
The above shows that to have healthy teeth in a horse it is most important to have a good diet and feeding pattern. Dental care can improve the performance of a horse when feeling no pain; it can masticate efficiently to gain all the energy and nutrients from the feed. This improves overall balance and condition. It is extremely important to have regular examinations to maintain healthy teeth. Having teeth checked annually or six monthly is important for preventative health care.
This section is to discuss routine dental examinations, identify the importance of regular dental checks, basic procedures, techniques, different types of restraints, and describe aspects of relevant UK legislation.
Importance of regular dental checks
The importance of regular routine dental examinations are vital for the well being of a horse .If a horse can not eat due to poor dental care; many problems may occur and eventually could lead to death. Regular dental examinations are good preventative health care. This improves the quality of the life of a horse in balance, overall condition, performance and enables maximum potential.
It is essential that all horses have an external examination, prior to the closer examination of the internal hard and soft tissues. Before this procedure is taken place it is important to ask the owner questions about the history of the horse. These questions should be: basic information regarding the horses, age, general health, diet, history of vaccinations especially tetanus, any previous dental records, and any behavioral abnormalities with eating or riding.
Tetanus is a highly fatal infectious disease. The toxins it produces acts on the central nervous system, invading through open wounds. It makes the muscles in the body constantly spasm and effects all functions within the body. The prognosis is poor unless treated and diagnosed at an early stage. There is a vaccination for tetanus. Two injections are given at an interval of four to six weeks and can be done from four months old. Followed by booster vaccinations at six months or annually. It is vital that the EDT asks the owner of a horse if it is vaccinated against tetanus, if not no dental work can take place.
The EDT must get all the equipment needed for the examination before entering the stable other wise it will make the horse nervous, waste time and look unprofessional. The equipment required is a stainless steel bucket, a dental speculum, a dosing syringe, a dental mirror and also a light source.
First, as a safety measure the EDT should check the area where the dental examination is going to be performed. It must allow safe restraint, be free from any dangerous obstacles and have high ceilings and a non slip clean floor. The owner should to put a head collar on the horse before entering the stable. It is best for the owner to put the head collar on because the horse will know the owner and be more comfortable and not be upset by a stranger. The horse’s physical and general condition will be observed by the behaviour and the way it moves. This is done by condition scoring ‘condition scoring is a way of assessing your horse’s bodyweight or condition by its appearance’ (S. McBane, 2004). The areas of the horse used for this assessment are: the top of the neck, the back, ribs and the hindquarters.
It is crucial for an EDT to understand the behaviour of a horse and have good horsemanship skills. Horses have several instinctive behaviours, to herd; one mare tends to lead in a herd and is territorial. Horses also have responsive behaviours and react to voice, contact and handling, therefore it is essential to be quiet, calm and reassuring in the contact and handling of any horse. They also remember bad experiences so it is advisable to ask the owner if the horse has been looked at before and how well it behaved. Body language is also a good indicator to show how the horse will behave. Posture, head, and tail should be observed.
Once this has been done the external examination can take place. ‘The head should be evaluated for symmetry, balance and gross abnormalities which may give clues to dental problems’ (Gordon.J Baker & J. Easley, 2005). The horse’s head should also be assessed, as this reflects the conformation of the dental arcades.
Next the temporalus muscles should be checked for asymmetry. If the muscle is more developed on one side it can very often mean that the horse favours one side more than the other.
Palpation of the temporalus muscle.
The temporal mandibular joint (TMJ) is then checked for discomfort, and the ears also for any pressure points or fungi growing within the ear cavity.
It is also important to check the parotid salivary glands for any swelling or abnormalities. During the spring due to eating the spring grass, they can become slightly enlarged.
It is essential that the submandibular lymph nodes and pharyngeal lymph nodes are checked as these can become swollen if the horse has contracted strangles.
Strangles is an acute contagious fever of horses, donkeys and mules’ (Boden.E, 2001). It is one of the most common equine respiratory infections it spreads quickly and can be fatal. The symptoms are: increase temperature, nasal discharge, coughing and enlarged pharyngeal nodes which become hot, tense and painful to touch. Up until 2006 a vaccine was available for the prevention of strangles (Equilius StrepE). It has now been taken off the market, due to a decrease in the antigen level within the vaccine, which dropped below the approved release requirements. There is no alternative vaccine for the time being.
Horse owners are advised to follow adequate stable management and hygiene procedures to minimise the risk of the disease. If a horse is suspected with strangles the owner should notify the vet and no further examination takes place. All instruments and clothing that have been in contact with the infected horse need to be sterilized. Horses that have come into contact with the infection need to be isolated.
To check for fractures, abscesses, and eruption cysts; run fingers and a thumb down the body of the mandible to allow any problems to be detected.
Eruption cysts occur up to the age of four, they are non painful enlargements as a result of normal tooth crown and root development of erupting permanent teeth and the shedding of deciduous caps.
Checking the head for symmetry and swellings.
Both eyes should be clear and free from lacrimal discharge. Standing in front of the horse, running both hands down either side of the face can help evaluate symmetry, checking the frontal, paranasal and maxillary sinuses for swellings.
The nasal passages should also be checked. Palpate the false nostril, ensure for asymmetry of airflow, odour and discharge from the nostrils, which can be either unilateral discharge (one nostril) or bilateral (both nostrils). The commissures of the upper and lower lips should also be checked for bitting damage and soreness (Gordon.J Baker & J. Easley, 2005).
Checking the incisors for number, shape and symmetry during practical.
The incisor teeth checked for number, shape and symmetry. From the side the angle ‘should be parallel to the angle of the facial crest which is usually about 10° - 15° relative to the lower molar table surface’ (JP Walmsley, 1993). The incisors characteristics should be used to assess the horse’s age by looking at the shape, colour, dental star and the galvayne’s groove.
Checking the incisors for abnormalities.
The TMJ allows a small amount of rostral and caudel movement, observe this by the relationship between the upper and lower incisor arcades when the chin is raised and lowered.
Determining the anterior-posterior (rostral-caudel) movement, (T.Allen, 2003).
Lateral excursion, is best evaluated standing to the side of the horse observing the range of lateral motion before tooth contact is made with the sloped portion of the opposite molar table. This helps estimate the width of the occlusal surface during mastication.
Hand position for the lateral excursion test to determine molar occlusion,
(T.Allen, 2003).
Checking the molar tables during lateral excursion.
The EDT must check the bars of the mouth (inter dental space) for canine teeth which have not erupted, rotated, or displaced and also for build up of tartar. By firmly running a thumb over the mucosa of the bars, feel for fractures, ulcers, ‘bitting damage’ and protuberances above and below the gum line.
Wolf teeth can be present; this is the first pre molar on the molar table and normally erupts between 6 to 18 months old. If present they are extracted as they can cause oral discomfort and training problems in bitted horses.
The speculum is placed on the horse for further examination. The speculum should be opened and the mouth washed out with a dosing syringe, so the oral cavity is ready for viewing and palpation, this is done using a head light and a dental mirror.
Placing the speculum.
Mouth being rinsed.
Checking for pathology with a light source
Checking for diastemas/caries and other pathology with a dental mirror
All of the pathology diagnosed must be written on a dental chart. This is important because it acts as a client database, invoice, observation and treatment all in one. It is professional to produce a dental chart for each horse, as it holds important and vital information such as vaccination status, previous dental treatment, reasons for presentation, and any relevant veterinary history.
Work can then begin to correct the pathology found.
This can either be done using hand or power tools. The majority of the time I use power instrumentation. I have found that horses actually tolerate this much better and it is more soft tissue friendly. The type of instrumentation I use has a diamond coated cutting disc which reduces tooth very effectively and is far more precise than a hand tool, when it comes to taking down big overgrowths and rebalancing. Geriatric horses really benefit from this type of instrumentation, because the power instrument does not have the force of a hand tool therefore elderly horses with slightly loose teeth find it a lot more comfortable. There is a potential risk with hand tools, that you can loosen teeth further.
Disinfecting
EDT’s must always have good hygiene practice. It is crucial to minimise the risk and there are a few precautions which must be put in place: instruments must always be soaked in a mild solution of disinfectant, clean water in a bucket and instruments scrubbed in disinfectant between each horse. Once all the horses have been seen to the instruments should be scrubbed again in a high concentration of disinfectant, dried and packed away.
Disinfecting equipment
Different types of restraints used
The principles of restraint are: to avoid getting hurt, prevent injury to the equine and to treat the equine effectively. Any method of restraint requires good horsemanship skills and must take place in a safe environment and requires at least two people.
There are many techniques of manual restraint:
- A head collar
- Stocks
Also
- A rope twitch
- A humane twitch
- A skin twitch
All of these cause pressure on the sensory nerves which ‘releases the body’s painkillers and tranquilizers, endorphins and encephalins, a process that takes a few minutes’ (S. McBane, 2005).
Chemical restraint can be used for difficult horses and is carried out by injection and can only be done by a veterinary surgeon.
In the UK only veterinary surgeons can legally sedate by injection or oral paste and administer local anaesthetics. ‘Therefore it is illegal for non - veterinarians to even process such drugs’ (BEVA, 2005). Consequently any horse during such illegal acts will not be covered by the owners insurance and will be fully invalidated. ‘Injury to clients or bystanders during such illegal acts would also not be insured by the EDTS insurance, if any were in place’ (BEVA, 2005).
The BAEDT (British Association Equine Dental Technician) is an organisation for qualified professional Equine Dental Technicians, promoting the professional training of technicians and to provide greater understanding of the need for equine dentistry to the general public.
Veterinarians and practising EDT’s realised there was a great need for having a recognised examination and code of conduct for those who wished to look at horses teeth. This was to give the horse owning public and vets a list of people who have been rigorously examined by The British Equine Veterinary Association and the British Veterinary Dental Association, and have agreed to abide by performance guidelines, a code of conduct and who are all fully insured.
Proposed legislation for Equine Dental Technicians & the BEVA examination
Equine Dental Technician (EDT) Training and Examination in the UK
The term Equine Dental Technician (EDT) is the correct term for a layperson that has shown skill and experience in dealing with certain equine dental procedures. The law in Britain on equine dentistry (covered in The Veterinary Surgeons Act 1966) clearly specifies which equine dental procedures lay people can perform and which can only be carried out by registered veterinary surgeons. The current law, which will not be affected by new legislation due in shortly, allows certain designated routine equine dental procedures which are not considered to be acts of veterinary surgery to be performed by lay people whether they are trained or not. These are termed:
Category 1 Equine Dental Procedures and include:
- The examination of equine teeth
- Routine rasping (excluding the use of power dental tools)
- Removal of sharp enamel points and small dental overgrowths (less than 5mm high and involving less than half of the tooth's occlusal surface) with manual floats.
- Removal of digitally (finger) loose deciduous cheek teeth ("caps")
- Removal of calculus, which lies above the gum line.
A further group of procedures have recently been designated as advanced dental procedures. These can be performed by qualified EDTs who have passed the British Equine Veterinary Association (BEVA)/British Veterinary Dental Association (BVDA) examination. These advanced equine dental procedures are termed:
Category 2 Equine Dental Procedures and include:
- Extraction of loose teeth, including both cheek teeth and incisors, including deciduous cheek teeth or teeth suffering from advanced periodontal disease. However teeth which have been loosened by trauma must have further investigation by a veterinary surgeon - i.e. x-rays if necessary - before being extracted
- Extraction of normal, fully erupted and non-displaced wolf teeth
- Removal of large dental overgrowths (over 5mm tall and involving over 50% of the occlusal surface of the tooth) and overgrowths over 5mm tall of whole teeth.
- Techniques requiring the use of dental shears, inertia hammers and motorized dental instruments including power rasps.
- Treatment of fractured and diseased teeth.
- Extraction of dental fragments and palliative rasping of fractured and adjacent teeth.
Many of these advanced dental procedures will require sedation of the horse. These drugs can only be prescribed by a vet. Additionally, many cases will require Analgesics, Anti-Inflammatory and Antibiotic treatment following the above dental procedures. These drugs can also only be administered by a veterinary surgeon at present. Certain equine dental procedures will not be deregulated to equine dental technicians and can at the present, and in the future only be performed by veterinary surgeons. These are termed:
Category 3 Equine Dental Procedures and include:
- Any procedure which involves making an incision (except elevation of the gum for the purpose of intra-oral extraction of teeth under veterinary supervision)
- Endodontics (root canal treatment)
- Orthodontics (e.g. bracing parrot mouths)
- Repair of mandibular fractures.
For more information on legislation please visit the BAEDT website (www.baedt.com), and for also a full list of qualified EDT’s.
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The British Equine Veterinary Association
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Elsevier Saunders – Equine Dentistry Second Edition, 2005, Gordon J. Baker and Jack Easley.