Osteo-articular problems and lameness are a major threat for the athletic career of sporthorses. Therefore, it has become routine to screen youngsters radiographically for developmental osteo-articular abnormalities (DOAs). The results of this screening largely influence the economic value of the horse and determines whether it is suitable for breeding. However, there is ongoing debate which specific DOAs indeed have a functional impact. Secondly, selection by radiographic phenotyping of breeding horses should ideally be replaced by genotyping. And finally, since expensive novel reproduction techniques indirectly promote inbreeding, it should be investigated whether this entails an increased risk for DOAs. In a first work package (WP1), records of sound sporthorses admitted at Ghent University between 2009 and 2018 will be re-examined for the presence of DOAs, integrated with an established sport-results database and statistically compared to DOA findings for age-matched lame sporthorses examined over the same period. In WP2, 560 horses (1 case/3 controls) will be genotyped (HD 670 chip) and pooled with 440 previously genotyped horses for a genome-wide association study investigating susceptible loci for common DOAs. In WP3, the 1000 genotypes from WP2 will be analyzed by ‘runs of homozygosity’ to first assess levels of inbreeding and, after linking with the radiographic phenotype, to investigate secondly any associations between local inbreeding and the risk for DOAs.