Factors associated with completion of Fédération Équestre Internationale endurance rides (2012-2019): Modelling success to promote welfare-oriented decisions in the equestrian sport of endurance.

Abstract: Endurance riding is a popular equestrian sport organised at the international level by the Fédération Équestre Internationale (FEI). The sport involves prolonged exercise at speed over significant distances, which puts a substantial load on equine athletes' musculoskeletal systems and metabolism and contributes to the risk of injuries and other veterinary problems. The FEI employs a system of in-ride veterinary inspections aimed at early detection of such problems and elimination of horses unfit to continue in the ride. To date, risk factors for elimination due to irregular gait or metabolic problems have been the primary focus of scientific enquiry. The present study is the first large-scale multivariable study to report factors associated with the positive outcome of endurance rides - their successful completion. This retrospective observational cohort study used data from the FEI's Global Endurance Database. The study cohort included 74,629 starts made by 21,346 unique horses in one-day international-level competitions held worldwide between July 2012 and December 2019. Forty-one potential factors identified based on previous studies and a priori hypotheses were considered in the analysis. Univariable and multivariable logistic regression analyses were performed to investigate associations between ride completion and predictor variables and their interactions. The study identified 19 factors and four interactions associated with an increased or decreased likelihood of successful ride completion. High competition frequency (fewer days over mandatory out of competition period; Wald χ 71.35, P-value <0.0001), fast riding speed (236.57, <0.0001), upward changes in competition level and riding speed between two successive rides (103.59, <0.0001 and 87.60, <0.0001) were associated with a decrease in the likelihood of ride completion. These factors can be effectively regulated by appropriate rules and considered by athletes when planning competition schedules, preparing ride strategies, or indeed during the ride itself. Other identified factors, including horse and rider age, sex, completions and eliminations history, contribute to an estimate of the likelihood that a particular combination completes a ride and thus can aid veterinarians at veterinary inspections as additional inputs supporting their decision-making when assessing horses' fitness to continue in the competition. The study's main limitation is an absence of data on national-level rides. Such data and data on training and veterinary histories remain difficult to access and were unavailable for the analysis. The present study's results demonstrate that shifting the focus to modelling the positive outcome is a valuable approach offering evidence-based recommendations for good horsemanship, better-informed veterinary inspections, and welfare-oriented rules.