Assessment of sportive longevity in Pura Raza Español dressage horses

The current study aims to perform a genetic analysis on sportive longevity measured as the number of dressage tests, and examine factors affecting the length of the dressage competitive career in the Pura Raza Español (PRE) horse population. Dressage test results of national and international competitions in Spain of 1747 PRE horses between 2004 and 2014 (n = 23,650) were analyzed using survival analysis methodology. A grouped data model including sex, age at first test and competition breaks as time-independent effects, and the competition year, scores of the test, rider experience, test level and season as time-dependent effects was used. Higher relative risks (RR) of the ending competitive career were observed for horses which started competing at early ages and without any break during their competitive career. The horses that scored >76% in their dressage tests were less likely to have shorter competition careers (RR 0.14) compared to those horses scoring 1-55% (RR 1.78). The highest risk of ending the competitive career was observed in horses ridden by inexperienced riders. The risk of ending the competitive career increased exponentially in step with test levels. The heritability estimated (0.20 ± 0.01) for sportive longevity indicates that a certain response to direct genetic selection should be expected. Thus, using the number of dressage tests as a measure of sportive longevity could be a good option to maximize the horse's performance success. The number of dressage tests is a promising tool for the genetic analysis and evaluation of breeding values for sportive longevity.