Researchers delve into complications arising from cheek teeth removal in horses

A tooth is cut into sections after the crown fractured during extraction. Photo: Gergeleit et al.

A German study in which cases of cheek teeth removal from the lower jaw of horses were reviewed found that 6 percent developed clinically significant complications.

Ninety percent of the problems related to bone fragments remaining in the sockets, which complicated the healing process.

Hauke Gergeleit and Astrid Bienert-Zeit, with the Clinic for Horses at the University of Veterinary Medicine Hannover in Germany, said that while dental extractions are standard procedures in horses with diseased cheek teeth, they have a higher prevalence of complications compared to other common surgeries.

However, newer instrumentation, less invasive techniques, improvements in training, and advancements in sedation and pain management have made dental surgeries less debilitating for horses.

The pair, writing in the journal Frontiers in Veterinary Science, noted that complication rates related to extractions differed remarkably among studies, depending upon the techniques used.

For standing oral extractions, lower complication rates of 4% to 20% have been reported, making this the preferred method when possible.

However, despite dental advances, complications still occur in horses after removal of cheek teeth — the molars and pre-molars.

Gergeleit and Bienert-Zeit set out to learn more about complications arising from the removal of cheek teeth from the lower jaw, and to describe possible risk factors for their development.

They examined the clinical records of all such removals performed between January 2014 and December 2019 at the Equine Clinic at the University of Veterinary Medicine Hannover.

They examined the demographic data for each horse and the case details, including the position of affected teeth, the number extracted and the extraction technique.

Diseased cheek teeth that were readily extracted (either by hand or within 15 minutes through the use of forceps) were not included in the study.

In all, 302 procedures were included in the study, of which 20 (6.6%) gave rise to clinically significant complications requiring repeat referrals.

Healing problems usually became clinically obvious 1 to 2 weeks after extraction.

Bone fragments in the socket, known as alveolar sequestration, were the most prevalent complication, making up 90% of them (18 of the 20 horses).

A fistula developed in 5 of the 20 horses.

Horses developing complications tended to be younger than the overall population, they found.

All cases were successfully treated, including removal of the troublesome bone fragments and wound debridement. However, some cases took up to five months to resolve.

The authors say anatomical features of the lower jaw sockets and bone appear to make horses more prone to bone-fragment problems.

Discussing their findings, the researchers said their clinical impression that post-operative complications associated with cheek tooth extraction from the lower jaw are relatively common was supported by their study.

Post-operative complications had occurred with all extraction methods in this study. They found no direct correlation between surgical time, final extraction method and the severity of complications.

“One would anticipate a higher complication rate for longer and more complicated dental surgeries,” they wrote.  However, one 8-year-old Warmblood gelding, which had a tooth removed in less than 30 minutes, required continued removal of bone fragments for more than four months before complete healing occurred.

In contrast, another 8-year-old Warmblood gelding which had a four-hour surgery to remove the same tooth via a much more complicated method, via sectioning and repulsion, had no complications.

These different responses indicate that the complication rate is not only associated with the extraction method and the course of the surgical procedure, but also with the stage and severity of the underlying disease, the researchers said.

“Differences in the host’s immune response and in microbial challenge may also influence the development of post-extraction infections.”

The authors said complications associated with mandibular cheek tooth removal not only escalate treatment costs, but may also cause more serious issues than the initial problem.

“The treatments to correct these post-extraction problems are often more time-consuming and more difficult than for the original underlying disease.

“Consequently, it is essential that a thorough clinical and radiographic examination is initially performed in order to decide on the optimal extraction technique.

“Where the oral extraction process is not proceeding as planned, the radiographs should be reviewed and/or advanced imaging such as computed tomography sought.

“The risks of such extractions should be disclosed to the owner before the procedure and they should be advised how to recognize post-extraction complications.

“Increasing our knowledge of possible risk factors for these complications through studies like this and future similar studies will hopefully help to decrease the complication rates.”

Gergeleit H and Bienert-Zeit A (2020) Complications Following Mandibular Cheek Tooth Extraction in 20 Horses. Front. Vet. Sci. 7:504. doi: 10.3389/fvets.2020.00504

The study, published under a Creative Commons License, can be read here.

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