The use of a tongue tie alters laryngohyoid position in the standing horse

Abstract

The use of tongue ties in racing is common, yet there are few data to support their efficacy. In order to make appropriate recommendations for clinical practice and policy on tongue ties, data documenting their effect on upper airway structure are necessary. To determine the effect of a tongue tie on the resting laryngohyoid position of the standing horse. Experimental study. Twelve normal Standardbred horses were subjected to ultrasonographic measures of laryngohyoid position during 3 phases of tack application: Phase I--halter and lead; Phase II--bit, bridle, harness and check applied; and Phase III--as in Phase II but with the tongue tie added. Compared to Phase I, during Phase III with the application of a tongue tie a significant difference between lingual process position was noted both rostrally and caudally (P<0.001 and P<0.001), such that the tongue tie resulted in an increase in lingual process depth. The tongue tie in Phase III resulted in a decrease in depth of the thyroid cartilage and basihyoid bone compared to the Phase I location (P = 0.007 and P = 0.0047). The use of a tongue tie has a significant effect on the basihyoid and thyroid cartilage positions in the standing horse. This is the first report documenting a difference in laryngohyoid morphology following the application of a tongue tie, providing evidence that the use of a tongue tie has a measurable effect on upper airway structure. The functional implications of this finding are yet to be elucidated.