Intercat aggression in households following the introduction of a new cat

Among households with multiple cats, half reported fighting between cats when the new cat was introduced. Approximately half of the people introduced the cats into the home by simply putting the cats together immediately. Neither age, sex, nor number of cats in the household was associated with current fighting (i.e. fighting that was occurring 2-12 months after the new cat was brought into the household); however, current fighting was associated with individual behaviors (i.e. scratching and biting) during the cats first meeting, outdoor access, and the owner's perception of the first meeting as unfriendly or aggressive.