DNA Test to Evaluate Genetic Predisposition of Labrador Retrievers to Developing Canine Hip Dysplasia: Applications

The success of eradication programs against canine hip dysplasia (CHD) based on radiographic diagnosis is low. Using diagnostic genetic tests might help combating CHD in preference to solely phenotype-based diagnosis. This study was aimed at developing a DNA test to determine susceptibility of Labrador Retrievers to developing CHD.

MATERIALS AND METHODS: 700 Labrador Retrievers were recruited. For each dog, a blood sample and a ventro-dorsal hip radiograph were taken. Dogs were divided into two groups according to their FCI (Fédération Cynologique Internationale) CHD score: Control group (A/B) and Dysplasia group (D/E). Genetic characterization of the remaining 235 dogs combining a GWAS and a candidate gene strategy allowed a case-control population association study. A predictive mathematical model was developed using logistic regression. Results were validated using an independent population of 114 dogs.

RESULTS: 250 markers were identified as being associated with CHD. The definitive model which included 7 SNPs showed an accuracy of 85% defined by the AUC (area under the ROC curve). Sensitivity and specificity for positive likelihood ratio points 2 and 5 were 93% and 58%, and 70% and 86% respectively.

DISCUSSION: This DNA test represents a significant advance in CHD early detection. It constitutes a useful tool for veterinarians to help choosing the most appropriate therapeutic approach once genetic predisposition is known. It is also applicable in selection processes, since breeders can have this information as soon as a blood sample can be collected. A shift towards genomic screening may contribute to eradicating CHD in the future.