Equine Science Update
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Survey of equine dental disorders
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Equine dentistry has been rather neglected over the past few decades. Graham Duncanson , a veterinary surgeon with an interest in equine dentistry, teamed up with Emma Brigham , an equine dental technician, to study the type and incidence of dental disease in horses in the UK. They recorded the details of dental examinations carried out on 100 horses.

Examination technique

They followed a standard examination routine. For each of the horses they would:

   *      Assess the general appearance of the horse. A condition score between 1 (cachectic) and 10 (obese) was assigned to each horse.
   *      Ask the owner about any signs that might suggest dental disease; eg quidding, pouching of food in the cheeks, head carriage problems, resentment of bit.
   *      Inspect and palpate the head and record any swellings or asymmetry.
   *      Part the lips and inspect the incisor and canine teeth.
   *      Open the mouth and examine the occlusal surface of the incisors. These findings were used to estimate the age of the horse. The owner was then asked what age they believed the horse to be.
   *      Assess the degree of lateral (sideways) movement of the jaw. Full movement (100%) was said to occur when both the lateral and corner lower incisors could be moved to a position outside that of the upper corner incisor, while the incisors remained in contact.
   *      Note the angle of the central incisors from the side
   *      Palpate the upper cheek teeth through the cheeks to assess any pain reaction.
   *      Inspect and palpate the mouth using a Hausmann`s gag. The gag was initially opened to one notch and then released to accustom the horse to its use. It was then opened to 2 or 3 notches . The cheek teeth were examined using a pen torch or head lamp. The cheek teeth, tongue and cheeks were palpated. Any malodorous smell was noted.

Findings

   *      sharp points (on the lateral aspect of the upper cheek teeth and the inner aspect of the lower cheek teeth) were present in all 100 horses.

common abnormalities included

   *      dental calculus on canine and incisor teeth; and restricted lateral movement of the jaw, which were each present in about a third of the horses.
   *      `hooks` -were present in 37 horses: on only the first upper cheek teeth in 15 horses; on only the last lower cheek teeth in 11; and on both first upper and last lower cheek teeth in 11.

Less common findings were:

   *      wolf teeth(on both upper jaws in 7 horses, and on one upper jaw in 3 horses)
   *      parrot mouth (ie the upper incisors were rostral to the lower incisors but still had some occlusal contact) was found in 7 horses.
   *      incisor caps were present in 7 horses.
   *      loose teeth (5 horses)
   *      wave mouth- ie undulating occlusal surfaces in a rostral to caudal direction. (5 horses).
   *      stepped mouth - ie the occlusal surfaces of the cheek teeth of the lower jaw were not level but rose in steps as they progressed towards the back of the mouth. (4 horses).
   *      cheek teeth were missing in 3 horses. In one case the tooth on the opposing jaw had overgrown enough to prevent sideways movement of the jaw.
   *      unerupted canines ( 2 adult mares; one 3 year old gelding)
   *      shear mouth-defined as when the occlusal surface of the cheek teeth was angled at more than 40 degrees from the horizontal. Only one side of the mouth was affected in the 2 cases seen.
   *      fractured teeth

Treatment

   *      Sharp buccal edges of the upper cheek teeth and lingual edges of the lower cheek teeth were rasped. The Hausmann`s gag was always used to provide access for rasping the lower cheek teeth. No problems were encountered with the use of the Hausmann`s gag.13% of the horses required sedation ( only 3 horses required sedation for routine rasping ; the others required more extensive work using a motorised burr).
   *      Dental calculus was removed from incisors or canines as necessary.
   *      Incisor caps were removed.
   *      Incisors were rasped to correct alignment in 2 horses.
   *      Long mandibular canine teeth were cut halfway down and rounded off with a rasp in 12% of the horses.
   *      3 wolf teeth were removed.( from 1 of the 3 horses that had one wolf tooth; and 2 of the 7 horses with 2 wolf teeth). "We don`t believe that all wolf teeth cause problems" said Mr Duncanson. "But poor technique in removing wolf teeth may well lead to problems - either behavioural if the horse was hurt or frightened during the procedure; or physical if remnants of the tooth are left."
   *      In the horses with stepped mouth and wave mouth, the cheek teeth were rasped to balance the lower arcades.
   *      In horses with shear mouth, the upper and lower arcades were rasped to remove excessive angulation. The opposite side was balanced and the incisors were realigned
   *      Hooks were rasped by hand or using a motorised (Dremel) grinder with a guarded tungsten carbide grit burr. The high incidence of hooks may have been due to lack of full dental care in the past.
   *      Loose cheek teeth (all in animals older than 18 years ) were removed through the mouth under sedation using molar forceps.
   *      Fractured teeth were removed through the mouth under sedation using molar forceps.

All of the cases in this study had problems which the owners felt were related to the teeth but that they considered did not require veterinary attention. "In our opinion the removal of loose or fractured teeth is an act of veterinary surgery" , said Mr Duncanson. "But we don`t think that removal of teeth should be restricted to veterinary surgeons. Rather, it should be done by an EDT only under veterinary supervision. In this series of cases a veterinary surgeon was present for all of such procedures both to supervise the surgery and to administer sedation, antibiotic and tetanus antitoxin."

"The highest standard of equine dental care requires very close cooperation between veterinary surgeons and dental technicians" said Mr Duncanson.

For more details see:

Case study of 100 horses presented to an equine dental technician in the UK
E J Brigham and G R Duncanson
Equine Veterinary Education (2000) 12; (2) 63-67

Glossary

Buccal  :  the surface next to the cheek

lingual  :  the surface next to the tongue

Rostral  :   nearer to the front of the head

caudal  :   nearer the tail

occlusal  :  the grinding surface of the tooth