VIDEOENDOSCOPIC ASSESSMENT OF DYNAMIC LARYNGEAL FUNCTION DURING EXERCISE IN HORSES WITH GRADE-III LEFT LARYNGEAL HEMIPARESIS AT REST - 26 CASES (1992-1995)

Objective-To evaluate laryngeal function by means of videoendoscopy du ring high-speed treadmill exercise in racehorses with grade-III left l aryngeal hemiparesis at rest and to determine outcome of treatment. De sign-Retrospective study, Animals-26 racehorses. Procedure-Videoendosc opy of the larynx was performed while horses were at rest and exercisi ng on a treadmill. Horses were classified as having grade-IIIA, -IIIB, or -IIIC laryngeal hemiparesis on the basis of the degree of arytenoi d cartilage abduction maintained during exercise. Postoperative racing performance was determined by evaluating race records and conducting telephone surveys, Results-20 (77%) horses had grade-IIIC laryngeal he miparesis tie, severe dynamic laryngeal collapse during exercise). Eig hteen underwent surgery, End racing performance was improved in 9. Fiv e (19%) horses had grade-IIIB laryngeal hemiparesis tie, left arytenoi d cartilage and vocal fold were maintained in an incompletely abducted position during exercise). Four underwent surgery, and racing perform ance was improved in 1. One (4%) horse had grade-IIIA laryngeal hemipa resis lie, full abduction of arytenoid cartilage during exercise); sur gery was not performed. Clinical Implications-videoendoscopy is useful in determining dynamic laryngeal function in racehorses with grade-II I laryngeal hemiparesis at rest.