Genetics behind hip dysplasia in German Shepherds and Labradors

Abstract

Objective— To document genetic progress in improving hip quality of dogs maintained in a closed breeding colony to produce dogs for training as guides for blind people. Design— Prospective analysis of hip quality records from a breeding trial that encompassed 3 full generations and included some dogs born into the fourth and fifth generations. Animals— Hip quality was assessed for 2,037 German Shepherd Dogs and 1,821 Labrador Retrievers from 1980 to 1996. Procedure— A subjective hip score assigned by 1 radiologist was used to assess hip quality during the study period. In the past 8 years, the distraction Index was also used. Genetic change was produced by selecting a small percentage of dogs to be parents of the next generation. Dogs were selected to become parents of the next generation on the basis of estimated breeding values. These were calculated by combining observed values of individual dogs with known relationships in the population pedigrees to predict which dogs were the best candidates for selection as parents. Results— In < 5 generations of selection, the percentage of German Shepherd Dogs with canine hip dysplasia at 12 to 16 months of age decreased from 55 to 24 %. Among Labrador Retrievers, the percentage decreased from 30 to 10%. Clinical Implications— This report gives practitioners documented proof that genetic selection will work to improve hip quality. Dog breeders must be advised to be patient, however, to allow enough generations to elapse to make meaningful genetic change. (J Am Vet Med Assoc 1997;210:1474-1479)