Introducing new cats to multi-cat households: Results of a representative survey of Danish cat owners

Based on a quantitative questionnaire survey aimed at Danish cat owners representing the background population regarding a number of demographic parameters, we examined: 1) The use of different introduction techniques for new cats in multi-cat households; 2) the correlation between recommended practices for introducing new cats to resident cats in homes and the cats’ reactions to each other within the first month after introduction. Of 1507 cat-owning respondents, 308 had introduced new cat(s) to resident cat(s) among the cats living in their house at the time of the survey, and the study focused on these. Firstly, descriptive statistics served to map the prevalence of (i) 16 different introduction techniques and (ii) the new and resident cats’ reactions. Secondly, the study applied exploratory binary phi correlation tests (i) between new and resident cats’ reactions to each other and (ii) between applied introduction practices and reactions. Moreover, we also took the age of the cats into account, by disaggregating our analyses on age classes of the new and resident cats. We identified two main ways new cats are introduced: putting the cats together from the beginning (56% of respondents); and following recommended introduction techniques, including separation, use of barriers and scent exchange, exploration of each other’s areas, and using calming scents / pheromones / supplements / food. In general, the statistically significant associations between introduction practices and cats' subsequent reactions were not strong. However, the findings suggest that when both the new and resident cats are juvenile and/or young adults (< 4 years) applying separation, allowing the cats to explore the others’ areas, use of barriers, swapping scent and using calming scent pheromones are associated with agonistic reactions in the first month after introduction. On the other hand, if both the new and resident cats are mature (5+ years), use of barriers, engaging the cats in play in the same room and introducing additional resources are associated with affiliative relations. The reason for these results, especially in young cats, requires further investigation. Possible explanations for recommended introduction practices appearing counterproductive include that owners anticipate problems or apply the techniques after the cats have already displayed agonistic reactions to each other. • Cohabiting domestic cats may experience stress if there are conflicts between them. • How new cats are introduced to resident cats may influence the relationship. • ~50% of owners allow cats to meet immediately, and ~50% use gradual introduction. • No clear pattern is seen between introduction practices and cats’ initial reactions. • Gradual introduction when new and resident cats are young may be counterproductive.