Effect of a tongue-tie on upper airway mechanics in horses during exercise

Objective-To determine the effect of a tongue-tie on upper airway mechanics in exercising horses. Animals-5 Standardbreds. Procedure-Peak inspiratory and expiratory tracheal and pharyngeal pressures and airflow were measured while horses exercised on a treadmill with and w ithout a tongue-tie, Respiratory rate was also measured. Horses ran at spee ds that corresponded to 50 (HR50), 75, 90 (HR90), and 100% of maximal heart rate. The tongue-tie was applied by pulling the tongue forward out of the mouth as far as possible and tying it at the level of the base of the frenu lum to the mandible with an elastic gauze bandage. Peak inspiratory and exp iratory tracheal, pharyngeal, and translaryngeal resistance, minute ventila tion, and tidal volume were calculated. Data were analyzed by use of 2-way repeated-measures ANOVA. For post hoc comparison of significant data, the S tudent-Newman-Keuls test was used. Results-We were unable to detect significant differences between groups for peak inspiratory or expiratory tracheal or pharyngeal resistance, peak pre ssure, peak expiratory flow, tidal volume, respiratory rate, or minute vent ilation. Horses that ran with a tongue-tie had significantly higher peak in spiratory flows, compared with horses that ran without a tongue-tie. In the post hoc comparison, this effect was significant at 4 m/s, HR50, and HR90. Conclusion and Clinical Relevance-Application of a tongue-lie did not alter upper respiratory mechanics in exercising horses and may be beneficial in exercising horses with certain types of obstructive dysfunction of the uppe r airways. However, application of a tongue-tie does not improve upper airw ay mechanics in clinically normal horses.