Abstract
Introduction
The relationship between yearling laryngeal function (YLF) grade and race performance is unclear and warrants further investigation.
Materials and methods
The YLF from post-sale endoscopic examinations was graded, in duplicate, using the Havemeyer system and additional endoscopic abnormalities recorded. Race performance was evaluated for overall career and as two-, three- and ≥four-year-olds. Multivariable linear modelling examined the association between YLF and performance, with risk estimates presented as coefficients (95% CI).
Results
The YLF in 5,175 examinations was graded I in 29.8%; II.1 in 49.0%, II.2 in 16.5%, III.1 in 3.9%, III.2 in 0.8% and III.3 in <0.04%. Additional endoscopic abnormalities included VLAC (1.5%); mucosal lesions (7.6%) and DDSP (24.4%). Median (IQR) career earnings were: grade I $45,095 ($15,565, $113,220); grade II.1 $45,315 ($15,915, $107,490), grade II.2 $38,610 ($14,326, $95,218), grade III.1 $32,765 ($8,565, $86,030) and grade III.2 $35,810 ($3,700, $65,770). The multivariable model revealed no difference in overall career earnings for YLF grades II.2 and III.1, compared to referent grade I/II.1, whereas grade III.2 earned less overall (-$46,015 (95%CI: -$89,994, -$2,036), p=0.04). Earnings in ≥4-yearold were less for grades III.1 (-$35,076 (-$56,129, -$14,024), p=0.001) and III.2 (-$53,219, (-$76,062, -$30,375) p<0.001). Grades II.2, III.1 and III.2 had less career starts. Grades III.1 and III.2 had less career wins and placings.
Relevance to equine veterinary practice
Overall career earnings were not affected by YLF grades ≤ III.1. However, horses with grade III.1 YLF earned $35,076 less from 4 years old and upwards, compared to those with grade I and II.1 YLF.