Endoscopic evaluation of arytenoid function and epiglottic structure in Thoroughbred yearlings and association with racing performance at two to four years of age: 2,954 cases (1998-2001)

Objective-To determine the association between results of endoscopic evaluation of arytenoid function (AF) and epiglottic structure (ES) in Thoroughbred yearlings and racing performance at 2 to 4 years of age. Design-Retrospective case series. Animals-2,954 Thoroughbred yearlings, Procedures-Records of yearlings that had endoscopic evaluation of the larynx between 1998 and 2001 were obtained, and results were graded by use of standardized scales. A modified Havemeyer scale (grade II, II.1, II.2, III, or IV) was used to evaluate AF; ES was graded on a scale of 0 to IV Records were annotated if the epiglottis was subjectively short or narrow. Racing performance data were obtained from an online database. Results-Horses with grade II.2 AF had significantly less earnings at 4 years of age, compared with earnings of horses with AF grades < II.2. Grade I I I AF was associated with fewer starts and less earnings at 3 and 4 years of age. No horses met the criteria for grade IV AF Horses with ES grades > II had less earnings at 2 and 4 years of age, compared with earnings of horses with ES grades < II. A short epiglottis was associated with less earnings at 2 and 3 years of age. Conclusions and Clinical Relevance-Analysis suggested that yearlings with grade III AF had a decrease in athletic potential. Yearlings with grade II.2 AF, an ES grade > II, or a short epiglottis typically had decreases in racing performance. These factors should be evaluated carefully when developing purchase recommendations. (J Am Vet Assoc 2010;236:669-673)