Endoscopic assessment of airway function as a predictor of racing performance in Thoroughbred yearlings: 427 cases (1997-2000)

Objective-To compare endoscopic findings of the upper portion of the respir atory tract in Thoroughbred yearlings with their subsequent race records to determine whether subjective assessment of airway function may be used as a predictor of future racing performance. Design-Retrospective study. Animals-427 Thoroughbred yearlings. Procedures-Endoscopic examination findings were obtained from the medical r ecords and the videoendoscopic repository of the Keeneland 1996 September y earling sales, Racing records were requested for the yearlings through the end of their 4-year-old racing season (1997-2000). Twenty-nine measures of racing performance were correlated with endoscopic findings. Subjective ary tenoid cartilage movement grades were determined, using a 4-point grading s cale (grade 1 = symmetrical synchronous abduction of the arytenoid cartilag es; grade 4 = no substantial movement of the left arytenoid cartilage). Results-Of the 427 Thoroughbred yearlings included in this study, 364 estab lished race records, and 63 did not. Opinions regarding suitability for pur chase, meeting conditions of the sale, and the presence of epiglottic abnor malities had no significant association with racing performance. Arytenoid cartilage movement grades were significantly associated with many of the de pendent variables. However, palatine abnormalities were not predictive of i nferior racing performance. Conclusions and Clinical Relevance-Thoroughbred yearlings with grade-1 and -2 arytenoid cartilage movements had significantly better racing performanc e as adults, compared with yearlings with grade-3 arytenoid cartilage movem ents. In contrast, epiglottic and palatine abnormalities were not predictiv e of inferior racing performance. Therefore, evaluation of laryngeal functi on, but not epiglottic or palatine abnormalities, using the 4-point grading system, should be the major factor in developing recommendations for prosp ective buyers.