Dog Guardian Interpretation of Familiar Dog Aggression Questions in the C-BARQ: Do We Need to Redefine "Familiar"?

The C-BARQ familiar dog aggression (FDA) subscale contains four items relating to threatening responses towards familiar dogs in the same household (i.e., dog rivalry). In a recent study, we noticed that 92 of 157 guardians who owned only one dog completed the FDA items, generating an unexpected score. We followed up with participants to explore whether lifestyle factors influenced their completion of the FDA items. Singleton dogs with FDA scores were more likely to regularly participate in social activities with other dogs, with many scores based on such interactions with non-household dogs. The singleton dogs with FDA scores also had marginally lower fear-related C-BARQ scores compared to singletons with no FDA score and dogs living in multi-dog households. We then conducted a scoping review of articles using English versions of the C-BARQ and found wide variation in whether or not FDA scores were reported. Studies that reported significant FDA findings often did not indicate the proportion of scores in their data that came from singleton dogs, raising issues of accuracy and interpretation of the subscale. We discuss ways to clarify the interpretation of the FDA questions by dog guardians and hope to promote further consideration of practices to improve replicability across studies.