There is a proper way to introduce cats. You MUST let them play UNDERNEATH the quarantine door until they are no longer hissing and you are no longer seeing signs of stress (puffed tail, etc.). Cats should NOT be introduced, at all, until they are playing nicely under the door (without seeing each other or being in close bodily contact with each other). Cats will become friends at their OWN pace, not at one artificially imposed by the humans in the household. Unfortunately, and all too often, the humans become impatient and want their “kids” to get along with each other RIGHT NOW. This is a recipe for disaster, although I am sure than many cat behavioral specialists love when people introduce their cats too soon, as it makes for more business for them. Normally, it is the older and more established feline resident who objects to the newcomer/interloper. So, things must progress at the existing cat’s rate of acceptance, NOT based on the kitten or new cat’s desires for play or companionship. None times out of ten, it is the existing feline resident that is resentful of the new addition. You cannot hasten the introduction just because you want the two individuals to get along. All you will do, by forcing the introduction, is to create more animosity and resentfulness. And, if you continue to insist on introductions, when the cats are not ready, you can create a situation where they will NEVER get along. So, any time you have made an error in judgment and thought the cats were ready to meet, and they obviously are not getting along, it is best to start over. Separate the two culprits s that there is a solid door between them. Allow them to be able to interact ONLY underneath the door WITHOUT seeing each other. Allow things to simmer down and allow them time to get over their hurt feelings. Once they begin to “explore” each other UNDER the door, then swap their beds so that they can get used to each other’s odor. Once they are sleeping on the other cat’s bed, comfortably, swap the beds again. If there is no reaction, whatsoever, to the bed swapping AND they are no longer hissing through the door AND they are reaching under the door to play with each other, THEN and ONLY then, should you open the door and allow a face-to-face meeting.
Normally, two males will get along well with each other, but ONLY after proper introductions have been made. Likewise, a male and female will usually get along with each other. With two females, there is a 50/50 chance that they will or will not get along. An adult cat should always be altered prior to these introductions (unless it is to be used in a breeding program, of course). There usually is no problem introducing a kitten under six months of age that has not been altered, yet, from the “kitten’s” perspective. In other words, the kitten’s hormones have typically not kicked in, yet, and there is no “offensive” hormone odor for the existing cat and no dominance issues by the new kitten. BUT, the existing cat can still not be expected to immediately be overly enthusiastic about the kitten’s arrival. You MUST go through the introductory process at a rate acceptable to the existing cat.
