The shape of the horse's mouth and the fact that it does not open very wide makes it difficult to fully examine the cheek teeth as part of the routine dental examination. Even with dental mirrors it is difficult to get a good look at the whole of the dental arcades.
Rigid endoscopes can be used to examine the teeth. Hubert Simhofer and his colleagues at the University for Veterinary Medicine in Vienna have been assessing the value of the technique in field situations as well as in the hospital.
They examined a randomly chosen group of 300 horses, following a standardised examination protocol, according to a report in Equine Science Update. Starting at the back of the right upper dental arcade, they gradually moved the scope forward, examining the masticatory surfaces. Then they reintroduced the scope to examine the inside (lingual) aspect of the same dental arcade, and then the outer (buccal) aspect.
They repeated the process with the other dental arcades, and finally inspected the soft tissue - tongue, cheeks, palate and gums.
Sedation was required to examine the horses properly. A combination of detomidine and butorphanol was the most effective at providing sedation and limiting tongue movement.
The researchers found much higher levels of dental defects than had been reported previously. In particular they found:
Reporting the work in the Veterinary Journal, Simhofer concludes that this is a safe diagnostic technique that allows a very thorough visual examination of the equine oral cavity.
In another study, intra-oral endoscopy also proved useful in identifying which tooth was damaged in horses with tooth root infections.
Removing a tooth may become necessary if the horse has a persistent tooth root infection despite treatment with antibiotics. However, tooth removal of a horse's tooth is not something to be undertaken lightly. It is important that the right tooth is removed. This is particularly so if the tooth is to be removed through the mouth.
Peter Ramzan a veterinary surgeon working in the Rossdale's practice at Newmarket conducted a study to assess if examining the cheek teeth with a rigid endoscope helped confirm which tooth was involved.
In a report in the Equine Veterinary Journal he describes seventeen cases of tooth root infections that had not responded to antibiotics and that had no defects apparent in the oral surface of the tooth. In fifteen (88%) of those horses, oral endoscopy revealed abnormalities on the oral surface of the affected tooth that had not been visible to the naked eye.
He concludes that in most cases of tooth root infection there is visible evidence of damage in the mouth to identify the affected tooth. Although the damage may not be visible on a standard visual examination, it is usually detected if the teeth are examined with a rigid endoscope.
He suggests that oral endoscopy should be considered as an additional diagnostic tool in cases of tooth infections in horses.
Oral endoscopy as an aid to diagnosis of equine cheek tooth infections in the absence of gross oral pathological changes: 17 cases.
Equine Vet J (2009) 41, 101- 106.