Osteochondrosis dissecans (OCD) and Birkelandfracture, are diseases mainly in the hock and fetlock joints of varmblooded horses, respectively, that increase the costs in the horse industry and affect animal welfare negatively, since many horses have to be operated. The diseases contribute to increased costs for treatment and restitution, reduced performance and income as well as reduced value of the animal itself. High frequencies of the diseases illustrate the importance of revealing the causative nature of OCD and POF.
Selection can be used as a preventive means towards such diseases, either on the quantitative trait loci (QTL) itself or on estimated breeding values, by summing the effect of all alleles into a genomic breeding value. The project aimed at verifying QTL findings that have been reported by Lykkjen and coworkers for OCD and POF in the Standardbred trotter. By considerably increasing the size of the material of Lykkjen and coworkers, only the finding of a QTL on chromosome 28 still held promise as a QTL. Our approach now is to use the candidate gene approach to possibly reveal the underlying causative gene. With only one QTL left to consider, this indicates that future research towards improving the genetics of OCD and POF should be approached by not only utilizing some of the genetic variance through a QTL approach, but rather to utilize more of the genetic variance through genomic selection, across populations of trotter, but also including data from riding horse populations. Such data will in main be available through research projects. Such an across-population initiative on OCD can be considered a model for other diseases, as well, and even for other species that do not either have a disease recording system in place.
In the same material, we also estimated the effect of inbreeding on racing performance. The effect was negative, i.e. that racing performance in Standardbred trotters is concluded depressed by inbreeding In corollary, crossbreeding is encouraged, and is one explanation of the recently increased contribution of French trotter in the Norwegian population of Standardbreds.