Racing unshod improves the speed, but not all horses have sufficient hoof quality to run barefoot repeatedly without risking health problems. If measures of the ability to race barefoot based on routinely recorded data can be used as a genetic selection tool, it will improve animal health and welfare and be of economic value. Knowledge about effects of racing barefoot on later performance is valuable for management decisions. Very few studies incorporated large field data on performance under different shoeing conditions, and genetic analysis of such data is lacking. This project aims to study if we can select for the ability to race barefoot in trotting horses, to indirectly improve hoof quality and performance. Different traits related to the proportion or number of barefoot races within a set period will be analysed. Correlations with the performance traits in the genetic evaluation will be estimated, as will effects on racing longevity from racing barefoot early in the career.