The effect of the laryngeal tie-forward procedure and soft palate cautery on nasopharyngeal diameter in horses.

The laryngeal tie-forward (LTF) procedure has been shown to move the larynx rostrally and dorsally whilst repositioning the basihyoid bone caudally and dorsally. Other studies have shown that the position of the hyoid bones influences the size of the nasopharynx. The effect of the LTF procedure on the size of the nasopharynx is unknown. It was hypothesised that the LTF procedure would result in a decrease in dorsoventral nasopharyngeal diameter. Twenty-five thoroughbred horses which underwent LTF with or without soft palate cautery (LTF±SPC) for treatment of dorsal displacement of the soft palate were included in this study. Preoperative and postoperative lateral radiographs were used to determine changes in laryngohyoid position and nasopharyngeal diameter. The LTF±SPC procedure resulted in a significant reduction (14-17 per cent) in dorsoventral nasopharyngeal diameter (P<0.001). The LTF procedure decreases nasopharyngeal diameter. The impact on upper respiratory tract function during exercise remains unclear.