Endoscopy of the upper respiratory tract at Australian Thoroughbred yearling sales: Can we do better?

Summary

Post-sale examination of the upper airways (scoping) is commonly performed at Australian yearling sales to determine whether there is evidence of upper airway dysfunction that might influence future racing performance, and hence nullify the sale. However, ambiguity surrounding the assessment of yearling laryngeal function and how it relates to future performance has led to concerns regarding the process and reduced buyer confidence. The current protocol for post-sale endoscopic examinations at yearling sales, as listed in the conditions of sale, is disadvantaging all sides of the industry. Yearlings with a grade 3/5 laryngeal function score meet the conditions of sale, but an increase in pre-sale endoscopy has arisen due to concerns that horses with grade 3 laryngeal function may perform less well than yearlings with “normal” laryngeal function (grades 1-2). Yearlings with grade 3 laryngeal function, apparently identified pre-sale, fetch a lower sales price even though it is estimated that most will not develop a performance-limiting upper respiratory tract obstruction. The 5-scale grading system currently used to grade post-sale endoscopic examinations does not allow subcategorisation of intermediate laryngeal function and has largely been superseded, worldwide, by the 7-scale (Havemeyer) system, although it remains uncertain whether or not this offers any further advantage in predicting future performance.
In this study, key industry groups, namely Thoroughbred breeders and veterinarians involved in yearling endoscopy, will be engaged to investigate current concerns surrounding yearling sales endoscopy and discuss different laryngeal function grading systems and potential improvements to the current process. A large retrospective study (of a minimum of 5000 post-sale endoscopic examinations) will be performed to investigate the relationship between post-sale laryngeal function score in Thoroughbred yearlings and future performance. The results will be used to determine the validity of the current yearling sales endoscopy process and guide future recommendations.

Program

Thoroughbred Horses

Research organisation

The University of Adelaide