Genetic variation in aggression-related traits in Golden Retriever dogs

In this study, heritabilities of several measures of aggression were estimated in a group of 325 Golden Retrievers, using the Restricted Maximum Likelihood method. The studied measures were obtained either through owner opinions or by using the Canine Behavioural Assessment and Research Questionnaire (CBARQ). The aim of the study was to determine which of the aggression measures showed sufficient genetic variation to be useful as phenotypes for future molecular genetic studies on aggression in this population. The most reliable heritability estimates seemed to be those for simple dog owner impressions of human- and dog-directed aggression, with heritability estimates of 0.77 (S.E. 0.09) and 0.81 (S.E. 0.09), respectively. In addition, several CBARQ-derived measures related to human-directed aggression showed clear genetic differences between the dogs. The correlation between the estimated breeding values for owner impressions on human- and dog-directed aggression was relatively low. The low correlation suggests that these two traits have a partially different genetic background. They will therefore have to be treated as separate traits in further genetic studies.