Population structure, inbreeding trend and their association with hip and elbow dysplasia in dogs

The aims of this study were to examine population structure and inbreeding trend in six dog breeds in Finland and to assess the inbreeding depression for hip and elbow dysplasia. Data consisted of 289 569 dogs, of which 36 92 4 dogs also had a record for hip and/or elbow dysplasia screening. From the early 1980s onwards, inbreeding trends were decreasing in the Golden Retri ever, the Labrador Retriever, the Rough Collie and the Rottweiler, probably as a result of importations of dogs, and somewhat increasing in the Finnis h Hound and the German Shepherd. When analysed per generation, observed mea n inbreeding coefficients were higher than the expected ones in each breed, indicating that breeders have not actively avoided inbreeding. As a class effect, the inbreeding level was significant only for hip dysplasia in the Labrador Retriever and the German Shepherd breeds. As a regression, inbreed ing level of a dog had only a minor effect on both of the dysplasias. Hip d ysplasia in the Labrador Retriever appeared to be more influenced by longer term aggregation of homozygosity (long-term inbreeding) in animals than by shorter-term inbreeding. When analysed from two data sets with a minimum o f five and two ancestral generations for each dog in the data, a statistica lly significant association between hip dysplasia and inbreeding for the La brador Retriever could be detected only in the former data set.