US and Canadian cat caregiver's ratings of cat-cat interactions: A video-based survey

US and Canadian caregivers (n = 6,529) of two domestic cats (Felis catus) were recruited to participate in an online cross-sectional questionnaire to assess: (1) knowledge of inter-cat behaviour; (2) the frequency of positive and negative cat-cat interactions in the home; and (3) factors associated with positive and negative cat-cat interactions in the home. The questionnaire included ten videos (five negatively valenced, five positively valenced), in which participants scored: the overall cat-cat interaction; cat 1's experience; and cat 2's experience, using a Likert scale. Participants were also asked to report how often they see each interaction in their own two cats. Cat behaviour experts (n = 5) were recruited to rate their interpretations of the videos using the same Likert scale as the cat caregiver participants. Overall, our results suggest that overt positive interactions (allo-grooming, co-sleeping) were more likely reported if cat dyads were related or spent more time living together, were neutered males, indoor-only, and/or had a single feeding area. Overt negative interactions (fighting, striking) were more likely reported if dyads were older or had a larger age gap, showed animal-directed aggression, were declawed, and/or had a single litter-box. Participant versus expert ratings of the videos were similar, however caregivers reported certain affiliative behaviours more positively than experts. Caregivers appeared to have a good understanding of their cats' overall relationship, as this aligned with reported cat-cat interactions. These results increase our understanding of the cat-cat relationship in two-cat households, which may be used to inform cat adoption strategies, in-home management, and promote a positive cat-cat relationship.