Equine Oral Endoscopy

Equine Oral Endoscopy 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.  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:

• sharp enamel edges - on the outside edge of the upper cheek teeth and the inner edge of the lower cheek teeth. These were present in almost all horses (96.3%) especially on the fourth and fifth upper cheek teeth (09s and 10s using the triadan system). 
• focal overgrowths (64.3%) - These were mainly seen at the rostral (front) aspect of the first upper cheek tooth (106 and 206) or the caudal back aspect of the last upper cheek teeth (111 and 211
• fissure fractures (54.3%) and - these were most common on the third, fourth and fifth lower cheek teeth. (308, 309, 310 and 408, 409, 410)
• infundibular hypoplasia /caries (48.3%)
   

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.

References:

The use of oral endoscopy for detection of cheek teeth abnormalities in 300 horses.
H Simhofer, R Griss, K Zetner
Vet J (2008) 178, 396 - 404.

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