Abstract
Dynamic respiratory endoscopy (DRE) can be used to objectively evaluate laryngeal function. This study hypothesized: (1) laryngoplasty (LP) would improve arytenoid cartilage abduction and rima glottidis area; (2) post‐LP arytenoid abduction at rest could be used to predict arytenoid position during exercise; and (3) no additional forms of dynamic upper airway collapse would occur. Using DRE, representative images were obtained in Thoroughbred racehorses pre‐and post‐LP during rest and strenuous exercise. Left‐to‐right arytenoid cartilage angle ratios and rima glottidis area ratios were calculated from each image, to correct for magnification and allow intra‐and inter‐horse comparison. Statistical analysis was performed using linear regression; t‐tests; and Pearson’s correlation coefficients with P < 0.05 considered significant. All 28 horses demonstrated left arytenoid cartilage collapse during exercise. Exercising ratios post‐LP were significantly (P < 0.001) larger than exercising ratios pre‐LP. A positive linear relationship (r ¼ 0.73) was found between post‐LP resting and exercising ratios. Following LP 9 horses developed additional forms of dynamic collapse and these horses had significantly (P < 0.03) smaller arytenoid cartilage ratios compared to horses that did not develop additional dynamic collapse. The study quantified an improvement in upper airway function after LP using DRE. Furthermore, it was found resting endoscopy can be used to predict post‐ LP arytenoid positioning during exercise. Our results reveal that additional forms of dynamic upper airway collapse may develop post‐LP; this complication is less likely to occur in horses with greater arytenoid abduction.