Many of the attendees had only recently begun to offer comprehensive dental care for their equine patients. Others have been on the cutting edge of equine dentistry for years. I can safely say that no one went away disappointed. The three days of lectures and discussions covered everything from the basics of equine dental anatomy and physiology and common dental disorders to surgical, periodontic (dealing with diseases of supporting and investing structures of teeth), orthodontic (dealing with irregularities of the teeth and their correction), and endodontic (focused on diseases of the tooth pulp) procedures, to the latest in dental diagnostic imaging and dental practice management issues. I have summarized the topics I feel horse owners might find most interesting.
Nothing But the Tooth
The lecture series kicked off with a trio from the University of Edinburgh, Scotland: Ian Dacre, BVSc, PhD, MRCVS; Nicole du Toit, BVSc, MSc, MRCVS; and Kirstie Dacre, BVMS, MSc, Cert EM (Internal Med.), PhD. (The Dacres have recently relocated to Massey University in New Zealand.) The three tag-teamed a fast-paced presentation, reviewing equine dental anatomy all the way from the gross (visible with the naked eye) to the ultrastructural (visible with powerful electron microscopes) to the histological (cellular) levels. While some of this information might seem esoteric, it is critical for a dental practitioner to maintain a detailed knowledge of the tooth organ--how it forms and how it responds to stresses. The tooth is mainly composed of living tissue, and it is an integral component of a living organism.
Ian Dacre also covered the physiology/biomechanics of mastication (chewing) in the horse. Normal dental wear is directly related to the time the horse spends chewing, with a long range of motion engaging as much of the chewing surface as possible. The more roughage a horse consumes in relation to concentrates, the longer he takes to eat and the more range of motion he uses to grind the food.
A horse with dental pain from dental pathology limits his range of motion to avoid the pain. Most of the current research strongly indicates that the single most compelling reason for comprehensive equine dental care is the prevention of dental pathology (i.e., malocclusions, periodontal disease, diseased teeth). If you prevent the development of dental pathology, you encourage normal dental wear, automatically making the horse comfortable and optimizing feed efficiency in the process.
Du Toit presented an overview of how the horse's dentition changes with increasing age. She reminded us that due to a wide degree of variability between individuals, "aging" a horse over the age of six years by the teeth is "highly inaccurate."
Each of the first two days, we had about 15 minutes to digest all the knowledge from the morning session while we grabbed lunch and hurried to one of four Table Topic discussions. This very popular "Table Topic" format is intended to be an informal interactive discussion where interested practitioners can share ideas, voice opinions, and ask questions of his/her colleagues. A facilitator knowledgeable on the specific topic keeps things flowing and makes sure everyone gets a chance to participate.
Of the eight topics offered, one in particular deserves a brief presentation to horse owners. Most are not aware of the educational background or particular qualifications of the practitioner they choose for their horse's dental care. There is currently no formal educational program for equine dentistry, i.e., no "certification" or "accredited" course work. Any licensed veterinarian can provide equine dental services. It's up to the individual veterinarian to obtain specialized training where he can find it.
Most owners know what board certification means. Many have used such specialized services for surgeries or complicated medical cases. The American Veterinary Medical Association (AVMA) recognizes several areas of specialization within veterinary medicine (i.e., surgery, internal medicine, ophthalmology, behavior, neurology). These specialty areas are overseen by "colleges" that decide what constitutes proper achievement within the specialty. These colleges conduct testing to confer upon veterinarians meeting their criteria Diplomate status within the college. Diplomates of a given college are "board-certified" in that specialty.
The only board certification status in veterinary dentistry is conferred by the College of Veterinary Dentistry. Diplomates of this college have achieved the highest level of recognition by their profession in veterinary dentistry. The College stresses small animals almost exclusively. Currently, there is no board certification in equine dentistry, and therefore there are no "specialists" in equine dentistry.
The Academy of Veterinary Dentistry (a "little sister" of the College) is pioneering a fellowship in equine dentistry with a view toward an eventual board certification status. The fellowship preparation and testing process is demanding, often requiring years to complete. Only one veterinarian, David Klugh, DVM, FAVD/Equine, of Gresham, Ore., has achieved fellowship status to date. Two others are currently preparing to sit for the exam. Promotion of this fellowship is the first step toward a true benchmark for measuring and recognizing a practitioner's skill in equine dentistry. The more veterinarians who achieve fellowship status, the higher the bar is raised in equine dentistry, and the better the care for the horse. Every equine dental meeting in the last three to four years has included an informational session for interested veterinarians to encourage more applicants for the fellowship.
Thomas Johnson, DVM, of Grass Lake, Mich., provided an overview of incisor teeth disorders and their treatment. His information stressed the importance of examining horses' incisors regularly so that abnormalities can be identified and treated early to avoid progression to more severe conditions. Proper incisor occlusion is critical for proper cheek teeth function and cannot be overlooked on routine examination.
Jack Easley, DVM, MS, Dipl. ABVP, of Shelbyville, Ky., discussed orthodontics in the horse. Orthodontic appliances are currently limited to use for correction of mandibular brachygnathism (parrot mouth). Severe cases can be improved through the use of an inclined bite plane fixed to the horse's upper incisors and hard palate. Again, he stressed the importance of early intervention for best success. While many cases cannot be completely corrected, most can be significantly improved.
Veterinarians have an ethical obligation to explain the possible genetic component of the parrot mouth malocclusion to the owner. Corrective procedures are deemed medically necessary to maintain the animal's ability to prehend (bite, as in grazing grass) and masticate food as he matures, and they are not intended for cosmetic purposes.
Leon Scrutchfield, DVM, MS, of College Station, Texas, discussed wolf teeth, which are actually vestigial premolars. The wolf tooth serves no useful purpose to the horse, can often cause discomfort, and therefore should be routinely extracted before the horse is introduced to the bridle. Wolf teeth usually erupt before one year of age, and the earlier they are extracted, the easier the procedure. Horses can have up to four wolf teeth, or they can be unerupted (beneath the gum), so careful inspection is necessary. Local anesthetic is easy to administer and facilitates routine extraction. Wolf teeth are sometimes fractured at extraction, leaving behind a fragment of root. This is usually not problematic.
Spaces Between Cheek Teeth
Padriac M. Dixon, MVB, PhD, MRCVS, of the University of Edinburgh, discussed cheek teeth diastemata (space). The cheek teeth in the horse are normally packed tightly against each other so that there is no space between them. If an abnormality occurs to create or allow a space between two or more cheek teeth, food accumulates and packs in the space, causing painful inflammation, infection, eventual disruption of the periodontal structures (periodontal disease), and tooth loss. The progression of periodontal disease is painful and might be the most significant dental disease in the horse. Treatment options are relatively new, but they show promise for reduction of inflammation and pain. Prevention through proper prophylactic care is best.
B. A. Rucker, DVM, of Lebanon, Va., presented a method increasing in popularity for treatment of some diastemata (spaces between teeth) and resultant periodontal disease. Widening of a small space where food is tightly packed can sometimes allow trapped feed to move out, alleviating the inflammation and allowing healing to begin. The procedure, called diastema burring or widening, is not beneficial in all cases, but it can be quite helpful with careful case selection.
While horses do not get "cavities" in the same sense that humans do, certain structures within the tooth are prone to "carious lesions" or decay. Tom Johnson, DVM, described caries (decay) of the infundibulum (a crescent-shaped depression in the central crown of a tooth) that is believed capable of weakening the tooth to the point of fracture if left unchecked. Some of these teeth might benefit from "restoration" (or filling). Ian Dacre discussed decay of the peripheral cementum (tissue that covers much of the visible portion of the tooth) that can be progressive and lead to periodontal disease and tooth loss.
July 31 started with a session on treatment of root infections in cheek teeth. In most cases, an infected cheek tooth can only be effectively treated by extraction. Consequently, four of the six lectures on this topic dealt with extraction techniques and complications.
In summary, there are three general ways to get a tooth out of a horse's head: 1) extraction via the oral cavity; 2) repulsion (punching) of the tooth with a steel punch and mallet from deep within the bone of the maxilla or mandible via a hole created with a chisel over the tooth root apices; or 3) removal via a buccotomy approach (from the side of the face or jaw, through the skin, mucosa, and bone to expose the roots and reserve crown, then prying the tooth from the socket).
If at all possible, a tooth should be removed in the standing, sedated horse through the mouth, which results in fewer complications by far than the other two techniques. Sometimes this is just not possible.
The highly invasive techniques of repulsion or buccotomy are necessary in some cases, but they are fraught with possible complications, including damage to adjacent healthy teeth, fracture of the diseased tooth or its associated bone, leaving fragments, and ongoing infection resulting in chronic draining tracts or sinuses. Subsequent surgeries to correct these problems are not uncommon. Meticulous radiographic imaging to precisely characterize all relevant structures, a high level of operator expertise, and the right tools increase the chances of success.
A more pleasing alternative to extraction of the infected tooth is endodontic therapy. These techniques, commonly known as "root canals," are in the pioneering stage in horses. Klugh noted that successful incisor root canals are more commonplace as the incisor anatomy is relatively easy to access. Cheek teeth root canals are not as successful at this time.
Several researchers are working with techniques to make this therapy a viable option for more horses. Hubert Simhofer, Dr. Med. Vet., from the University for Veterinary Medicine in Vienna, Austria, presented case examples from 11 horses receiving mandibular cheek teeth root canals accessed surgically from the root apices. Success rates can approach 80% in the hands of an experienced surgeon.
Later sessions focused on radiology and alternative imaging for dental disorders. The salient information gleaned from Safia Barakzai, BVSc, MSc, Cert ES(ST), Dipl. ECVS, of the University of Edinburgh, and Sara Puchalski, DVM, Dipl. ACVR, of the University of California, Davis, regarding diagnostic imaging was that radiography (X ray) remains the gold standard for imaging of the equine skull and dentition. However, when the diagnosis is complicated or unclear, modalities such as computed tomography (CT scan), magnetic resonance imaging (MRI), nuclear scintigraphy (bone scan), and ultrasound can be very precise diagnostic tools.
The major disadvantages of the first two are that they are expensive, require general anesthesia, and are not readily available in many areas. Eventually, these techniques will become commonplace, but in the meantime, improved radiography techniques, such as digital radiography and intra-oral views, have increased the sensitivity of the trusty X ray.
Bits, and No Bits
Day three opened with an excellent presentation by Dwight Bennet, DVM, PhD, from Fort Collins, Colo., on bits, bitting accessories, and bitless bridles. Bennet discussed numerous types of bits and paraphernalia that all had their specific place in equine performance. Despite this myriad of bitting choices, he emphasized that the most important component to the horse's headgear is the rider's hands.
He also stated that while many horses and disciplines require the use of a bit, if you don't need a bit for your purposes, don't use one! Remember, though, that some hackamores, side pulls, etc., can be more severe than a bit.
Teeth and Dressage
The rest of the morning was composed of short papers from 12 different practitioners. Of particular interest was a research project to determine the effect of occlusal equilibration (how the teeth contact the opposite teeth surfaces) on dressage performance from James Carmalt, MA, VetMB, MVetSc, MRCVS, Dipl. ABVP, ACVS.
Sixteen dressage horses, 11 of which had not had dental work performed for at least 12 months, and five of which had not had dental work done for at least six months, were randomly divided into a control group or a treatment group.
All horses (ridden by a single test rider blinded to the groupings) performed one of two standard dressage tests before two experienced judges (also blinded to the groupings). Then, the treatment group had dental equilibration performed under sedation using a full mouth speculum and power equipment while the control group members were sedated and had the speculum in place for the same length of time as horses in the treatment group, but no dental work was performed.
Forty-eight hours later, all horses performed the opposite of the two tests and were again scored by the judges. Results indicated that despite documented improvement in measurable dental parameters, occlusal equilibration performed in this group of dressage horses had no significant positive effect on performance as determined by the judges. In fact, one of two judges scored the treated horses significantly lower after dental equilibration. But the combined scoring of the two judges showed no statistical difference.
While it has a few inherent weaknesses in design (short interval to the second test, and the possibility that pre-treatment dental pathology was not severe enough to inhibit performance from the outset), the study is important in that it represents the first attempt to corroborate perceived or actual performance effects of dental work. Carmalt's research was performed at the University of Saskatchewan, Canada, but he now practices in New South Wales, Australia.
Kudos to the AAEP for bringing together such an outstanding group of presenters with such a broad range of information, and kudos to the nearly 400 equine practitioners who attended the largest meeting for equine dentistry in the world! The spread of this information will help horses live better, healthier lives.
- Arcade: a row of teeth, i.e., there are four arcades of cheek teeth and two arcades of incisors.
- Cheek Teeth: a general term used to indicate all the grinding teeth, the premolars and molars.
- Clinical Crown: the portion of the tooth visible within the mouth to be used for grinding.
- Deciduous (Baby) Teeth: first teeth that are replaced by permanent teeth.
- Equilibration: the act of correcting malocclusions to restore normal wear patterns to equine teeth.
- Eruption: the movement of the tooth crown out from the bone of the jaw into the mouth.
- Incisors: front teeth, just inside the lips, used to grasp, nip, and pull grass.
- Malocclusion: abnormal contact between opposing teeth.
- Maxilla: upper jaw, including the skull that houses the nasal cavities and sinuses.
- Mandible: lower jaw; articulates with the maxilla (upper jaw) at the temporomandibular joints.
- Mastication: the act of chewing or grinding food.
- Molars: Second three sets of large cheek teeth, top and bottom jaws, used for grinding. There are no deciduous molars; they erupt as permanent teeth.
- Occlusion: the contact points of opposing teeth; occlusal surface refers to the chewing or biting surfaces.
- Permanent (Adult) Teeth: teeth intended to remain for the horse's life.
- Premolars: first three sets of large cheek teeth, top and bottom jaws, used for grinding. There is a full deciduous set followed by a full permanent set.
- Reserve Crown: that portion of the tooth still within the bone that has not yet erupted for use in grinding.
- Root apices: the terminal tips of the roots where the blood and nerve supply enters, located at the opposite end of the tooth from the occlusal surface.
About the Author
Mary S. DeLorey, DVM earned her veterinary degree from University of Missouri in 1992. Since 2000, she has devoted her entire professional energies to equine dentistry. Her practice, Northwest Equine Dentistry, Inc. serves the states of Washington and Idaho and is based near Seattle. Dr. DeLorey has traveled internationally to instruct veterinarians in equine dentistry techniques and speaks to horse owners nationwide. She trail rides and raises sport ponies from her ranch in Eastern Washington when she's not on the road.
POLL: Colic Surgery