Computed tomographic study of the effect of a tongue-tie on hyoid apparatus position and nasopharyngeal dimensions in anesthetized horses.

The research investigates the impact of tongue-tie on the positioning of the hyoid apparatus and the dimensions of the nasopharynx and oropharynx in anaesthetized horses. The study finds that manually pulling the tongue forward does not significantly alter the dimensions or positioning of these structures.

Methods

• The study involved 5 adult horses. These horses were anaesthetized for the purposes of this study.
• Each horse was placed in sternal recumbency (lying on their chest) during two sequential computed tomographic (CT) scans.
• In the first scan, the tongue of the horse was left in its natural position within the mouth. In the second scan, the tongue was manually moved forward (rostrally) and held in place.
• Three-dimensional CT images were created and used to measure the dorsoventral (back-to-front) length of the hyoid apparatus (a series of bones that support the tongue) and the angles of the basisphenoid, basihyoid, and ceratohyoid bones that make up part of the hyoid apparatus.
• Using osseous (bony) landmarks for consistency, diameters and cross-sectional areas of the nasopharynx and oropharynx were determined on reformatted images in both the transverse (across) and longitudinal (lengthwise) planes.

Results

• The results showed no significant difference in any of the measurements taken of the hyoid apparatus when the tongue was in its natural position compared to when it was pulled forward.
• Similarly, no significant differences were detected in the dimensions of the nasopharynx and oropharynx, regardless of the position of the tongue.

Conclusions

• The results indicate that applying a tongue-tie (pulling the tongue forward out of the horse’s mouth) did not influence the position of the hyoid apparatus or the dimensions of the nasopharynx or oropharynx in anesthetized horses.
• In the context of horse racing, the study could find no evidence to suggest that tongue-ties are effective in maintaining the stability or patency (openness) of the nasopharyngeal or orolaryngeal airways during races.