Cat-to-Cat Introductions

By Jackson Galaxy

The common wisdom in introducing a newly adopted cat to a resident one in the past was to open the carrying case and “let them work it out.” We most definitely have a new way of looking at things; from the cat’s perspective. Cats are, after all, about territory. Bring a new, utterly alien scent of the same species into the house, and more times than not, we’re asking for chaos. Of course everyone has a story about introducing two cats that went smoothly doing the old fashioned technique. The point to stress is, if it goes poorly, this one meeting is the association that these two cats will hold onto for quite a long time and make a peaceable kingdom a difficult task. It is, ultimately, better to be safe than sorry.

It is crucial to recognize that it’s the cats who dictate the pace. With some, things go smoothly from the start, and they’re ready to be best pals in a matter of days. However, it is much more likely to take longer–weeks to months! We cannot emphasize this too much: it’s not up to you to decide how long each step should take! The cats themselves will signal when they’re ready to go to the next step.  If you too fast, you will jeopardize the whole process. 

A slow and steady introduction starts with the establishment of a base camp for the newcomer (see our article on setting up base camp). Once you’ve set up his or her space, you’re ready to start letting the cats make positive associations between one another. This is key, and will be repeated ad infinitum; all associations between the cats during this critical period have to be as pleasing as possible to reduce possible friction when they finally have free access.

Let’s start with one of the most pleasing motivators—food! Feeding time will happen at the door of base camp until introduction is complete. If the resident cat is not on a scheduled feeding diet, it might be best to put him or her on one for now. Or, if you leave dry food out and supplement with wet food, greatly decrease the amount of dry so that wet feeding time is looked forward to more. Remember that the only time either cat gets wet food is during these “meet and greets” at the base camp door, which can be divided into two daily sessions. Place food bowls on either side of the door with a couple of feet of breathing room for each cat. Ideally, there should be a family member on either side of the door to praise each cat as they eat. The idea is that they are rewarded with food for being so close to the scent of the unfamiliar cat, and also rewarded by you with praise for eating. At this initial point, the door should be closed; the cats can smell one another just fine. If they don’t devour their food at first, that’s okay. They will eventually eat. Don’t give in and move the food.

The next step is to open the door just a tiny crack, giving the cats limited visual access to each other. How soon do you move on to this step? As with all steps in introduction, pay attention to the cats; let their body language tell you when they are comfortable enough to move on. Remember that proceeding too quickly will force you to jump backwards by anywhere from a few days to a few weeks. Slow and steady definitely wins this race. We need to remain safe, so use rubber doorstops on either side of the introduction door to prevent any more than visual accessibility. If the door is too high off the ground to use stops, or if one or both cats are muscling the door open, try using a hook and eye setup. Instead of using it to lock a door shut, you would employ it backwards, to give us just a couple of inches of cracked space between the door and the jamb.

Again, the time required in moving from step to step is determined by your observation and the cats’ level of comfort. Keep cracking the door further until each cat could, if they wished, bat at one another—first up to the elbow joint then all the way to the shoulder, just making sure not to leave enough room to let a head get through. The object of “the game” is to give them enough rope to succeed. If they fail, just go back to the previous step.

Other tricks to use during the introduction period are “scent swapping” and “site swapping.” In scent swapping, we take a washcloth per cat and rub them down with it, making sure to go across their cheeks, head, sides, and around the base of the tail. Then, present the other cat with the scent of the washcloth in a conspicuous part of their territory, perhaps near a favored sleeping spot or near (but respecting the space of) their food or water. This will start getting them accustomed to the new facts of life; their space will have to be shared with one another, and better to have this fact introduced by scent than sight.

Site swapping relies on more paws-on physical exploration of one another’s space. Once a day, switch the two cats. The new cat gets to explore the house while the resident cat is base camp to freely explore the scent of new arrival without the fear of retribution. This process is best done with a human partner just to make sure the cats don’t inadvertently get in each other’s way while trading places; but if you don’t have help, try putting the resident in, say, a bedroom. When the new cat heads for the kitchen or other area out of sight, move the resident cat into base camp. Both cats should get the praise and encouragement they need/deserve in bravely going where they have not gone before!

Don’t forget, during this entire process, to play with the cats! This may seem elementary, but remember, they are just energetic balloons naturally, and even more so during these intense times of stress. Of course, you will have separate play sessions during the introduction phase. Once they’ve met and cohabitated for a bit, group playtime will be another wonderful way of diverting aggression they might have towards one another into a positive route. Refer to our article on play therapy to learn the ins and outs of keeping them both as happy as possible during the period of adjustment.

Additionally, consider flower essences to help both (or all) cats get through the initial introduction period with the least amount of stress and anxiety. Spirit Essences has many formulas to choose from, depending on the personalities involved, including “Peacemaker” and “New Beginnings.”

When you think it’s time to let them be in the territory together at the same time, take precautions. If a fight breaks out, do not try to break it up with your hands! Unfortunately, this is most of the time our first instinct. You are almost sure to be clawed and bitten, and it will not be pretty. In the heat of the moment, the cats will not be able to distinguish between your arm and each other, and they will have no inhibition about attacking whatever is handy, even if it’s you. Instead, have an immediate barrier like a couple of large, thick towels or blankets at the ready. You can toss them over the cats to disorient them, and immediately relocate them by scooping them up inside the towel (to protect yourself). There is no need to follow this up with a scolding. That will not do anything except increase the cats’ agitation, which is just what you don’t need! Let the event pass with each cat in their own “time-out”, and start again fresh tomorrow—at the very beginning. Also make sure that when the two cats meet, they have escape routes from one another. Getting cornered is a sure recipe for a fight in the mind of a defense-minded animal like a cat.

Keep a close eye on all interactions for the first week or so, not letting the cats have free access to one another when nobody is home. Finally, keep the food and litter setup established in the base camp room, at least for the next while. The accepted “recipe” is three litterboxes for two cats (to be precise, 1 box per cat + 1), so bear that in mind. Also bear in mind escape routes from the boxes, as the last place we want a skirmish to erupt is while one of the cats is having a “private moment.” They should be able to see as much of the room around them as possible when in the litterbox, which is why uncovered boxes would be highly recommended.

This should pretty well cover the bases for the initial introduction between your cats. Of course there are always variables, but the broken record theme should get you going; do it slow—there’s always tomorrow to make another positive impression. They can, over time, learn that every time they view or smell the other, something good will happen. Do it too quickly and that negative first impression might very well be the one that lasts.




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18 comments for “Cat-to-Cat Introductions

  1. tissigirl
    April 19, 2014 at 1:51 pm

    Thank you for this article, as well as the Base Camp article as well! We just adopted a very shy 2 1/2 year old very fluffy black kitty today. Our 15 year old male cat got along with my 2 other previous cats, both were calico alpha cats with attitude. Since he has been the only cat/pet for the last year and a half he has become very protective of his home however, so we want to make sure to take things very slow for both of them. The girl we just adopted lived with 3 other cats before she was in the shelter, so we think she will eventually be ok with our other cat as well. So far she has made it to a favorite hiding spot behind a few boxes for the last 2 hours, so we know it will be a slow process! We are still feeding our established kitty on the other side of the door, even though she will not come out to eat yet, so at least he can become accustomed to her smell and the ritual. So far he does not seem to be phased by the changes or the new smells in the least! I have never used any specific process in the past and have had a few minor issues because of that, so i’m very hopeful that this will prove successful. I can’t wait to have this sweet girl fully a part of our home!

    We are also using the Changing Times and Safe Space essences during the process, which helped our older cat with our move to a new home 6 months ago successfully.

  2. Jean Hofve DVM
    April 8, 2014 at 10:12 pm


    It’s time to move forward when you see *NO* reaction from either cat. Be patient! It can take a long time. It doesn’t sound like you are there yet, OTOH you seem to be getting close!

    BTW, multiple studies have shown that amitriptylline is not absorbed through the skin. At all. A vet should know this, and the compounding pharmacist should know it too, but sold it to you anyway.

  3. luvollieaustinbella
    March 30, 2014 at 6:03 pm

    Hello. I am wondering if someone out there can give me some advice on the current behavior of my two former best buddy cats who have fallen out after an episode of redirected aggression a few months ago. I kept them completely separated for several weeks because both myself and the kitties were so stressed (mostly me). Then I let the out in rotations so they could smell the other under the door. Fortunately I have 2 separate rooms, one for each cat. Now they have settled into their rotations but rare still acting anxious. One kitty is very intent to investigate the closed door where the other is staying and is on patrol upon hearing any noise. His tail slowly swishes and he sniffs closely. The other ignores the door but will not always finish his food outside the door. I think that’s mostly because he knows he goes into his room after dinner and is associating the evening routine with his alone time. No hissing from either cat. Here are other things I’ve tried

    Cat behaviorist. Her advice was good but I can’t find a way to keep them far apart to meet when alone with no one to help
    Prozac – disaster. The cat who attacked after redirected aggression flipped out after the 1st dose and was acting like he was in a fight (although he was alone). Paradoxical reaction
    Amitriptaline gel on ears (can’t see a difference)
    Spirit essences peace maker and bully remedy -don’t know if it’s working
    Feeding on either side of door. Going ok but one kitty will not eat with regularity because I am guessing he doesn’t want to go in his room or is too close to the door (or both) I can’t see the other kitty
    Playing outside the door with each
    Feeding treats when cats camp by the isolation room.
    Brushing with same brush
    Feeding on towel rubbed on the other cat
    Sock exchange

    When do you know it’s time to move forward? Is the swishing tail as I describe a sign of aggression or interest? Any other advice or info? I love my babies and want hope that my family can eventually come back together. Thanks so much

  4. Jean Hofve DVM
    February 11, 2014 at 10:57 am

    The same or different genders can get along perfectly well. Usually, young cats are more accepting than older ones, but that’s about the only generalization that can be made. It’s really more about personality. You know if you meet someone, you may take an instant liking or disliking to them…but if you do the introduction properly, either gender should be fine.

    Meanwhile, clean everything with a solution of 1 part bleach to 30 parts water, which will kill any viruses that may be hanging around. You might also want to read our article on Cancer Prevention and Treatment (even though FIP is not the same thing), because the ideas on strengthening the immune system and making your kitties as healthy as possible are applicable to any disease. See:

  5. Monkey2boo
    February 9, 2014 at 3:44 pm

    We originally got two kittens from the humane society (about 5 months ago). One recently died of FIP. We are currently in quarantine but I’m hoping to get another kitten in about 2 months. I have been told that I shouldn’t get another boy kitten to go with our current boy kitten. Are males really all that more territorial than females? I noticed, above, that you said there are “no rules”. So if we find a male kitten we like, we shouldn’t hesitate to bring him home as long as we are slow and careful in our introductions?

  6. reesesable
    October 10, 2012 at 10:33 pm

    Great. Thank you! Will take it slow and steady and at their pace. Thanks for such a great site! It has been a lifesaver for me! :)

  7. jhofve77
    October 10, 2012 at 8:19 pm

    Sable will probably remember her siblings, but that does not mean they would automatically get along. Four months is a long time, especially at that stage of development. It’s not possible to predict any particular interaction between cats; it depends so much on personality, and that has been changing as they have grown.

    In the long run, getting a younger kitten is as likely as any kitten to work out fine. But be sure to do the introductions correctly! Even a sibling to Sable should be treated as a stranger for intro purposes.

  8. reesesable
    October 10, 2012 at 2:30 pm

    Hi Jean,

    You were so right. I have been wanting to get a second kitten to keep the 1st kitten company, because things have been going exactly as you described. I haven’t done it yet for two reasons: I am not supposed to have pets at all in my apartment (although the landlord looks the other way, but 3 would be pushing it and I don’t want to risk my lease) and because I didn’t want the older cat, Reesey, to feel ganged up on by two kittens when one already seemed stressful. But since I am moving soon and since you indicate the interaction between the older cat and two kittens is likely to be better than the interaction between the older cat and the one kitten, Sable, I am about to get a second kitten.

    My question is, at this point, after 4 months, will Sable remember any of her siblings? I had thought to try to get in touch with the person I got Sable from to see if she still had any of the other kittens from that litter. If she doesn’t, one of my students found a 2ish month old kitten and is looking for a home for him. However, will the age difference (6 months) mean that the interaction between the two kittens won’t be all that positive? They will be in different stages and are different sizes. Should I try to find a kitten who is closer to the same age if I can’t get one of her original siblings?

  9. jhofve77
    June 2, 2012 at 7:22 pm

    Aggression is kind of an extension of fear; i.e., it’s how some cats express their fear. As they say, the best defense is a good offense! However, only hissing and not going into full monster mode is a good sign, overall. It’s quite a natural reaction to the surprise!

    As a general rule, it takes about 6 months for cats to fully and completely establish or reconfigure a relationship…and that goes for both of them! I don’t suppose you’d be willing to get *another* kitten to keep the new baby company? I generally recommend getting 2 kittens in a situation like this, as they will keep each other company, and the little one won’t be constantly pestering the adult to play (or finding other trouble to get into, like climbing the curtains, from boredom). And definitely, “friendlier” is not “friendly” and safety would demand separation while you’re gone. Hopefully you’ll have someone who will be able to spend time with them while you’re away; and you can proceed with integration, uninterrupted, when you get back. As far as Spirit Essences, give the office a call on Monday, and they’ll help you choose the right remedy, based on the personalities involved. :)

  10. reesesable
    June 2, 2012 at 4:41 pm

    Thank you for this great article. In January I adopted a stray cat, 3-4 year old female – the vet wasn’t sure, who had been hanging around my apartment complex. She is very sweet to me but, the few times I have seen with with other cats, takes an aggressive stance, even though the other cat was not acting in that manner. Despite this, after much reading and pondering and vacillating, I decided to get a second cat because my first cat seemed lonely and spends alot of time by herself (when I am at work and sleeping). I thought getting a kitten would give the best chance of amiable relations – thinking that the kitten would be nonthreatening to the first cat. So yesterday I adopted a 3 month old female kitten, also very sweet and playful (of course). I kept them apart yesterday evening and last night, trying to take my cues from them. The first cat had hissed just at the scent of the new cat on a blanket I put under her food bowl just after the kitten arrived. This morning, when I didn’t get any negative reaction from the older cat to the kitten’s sent all over me, I decided to try bringing them together. I came out of the base camp room holding then kitten and, after calling for a few minutes, located the older cat hiding under my bed. She didn’t even seem to see the kitten in my arms at first but went to look through the open door into base camp. When I finally got her attention directed toward the kitten, she did hiss, so I took the kitten back into base camp and have kept them apart the rest of today. Clearly I was overly optimistic about how quickly peaceful relations could be established. I have three questions: 1 – is my older cat’s reaction more about fear than aggression/territory (I am trying to determine with Spirit Essence to buy), 2 – I will follow the guidelines in this article to the letter but am afraid that the kitten, having come straight from being with her brothers and sisters and other cats in a busy home, is going to go through some separation anxiety and perhaps extreme loneliness since it is just me living here (and the hostile older cat) and I won’t be able to be in there all the time. How do I stave off loneliness for her? 3 – I will be leaving town for a few days this month. If I do get them friendlier before then, is it still best to go back to a base camp set up while I’m gone to ensure the stress of my leaving doesn’t translate to violence? Sorry this is SO long and thank you again for such a great article!

  11. jhofve77
    February 8, 2012 at 9:42 am

    I would definitely use flower essences in this situation. Contact Spirit Essences for recommendations.

    The principle of introducing one new cat to several residents is the same; you’d just be feeding the other 5 cats on the other side of the door instead of just one.

  12. Julie
    February 7, 2012 at 11:18 am

    I have ended up with 6 cats through rescue and various other means. Oldest is 15. Youngest is 3. They tolerate each other (although some get along really well). The oldest is the least tolerant and has spraying issues. A small female ended up on our doorstep in the cold the other night and I haven’t had luck so far finding another home. Is there a way to introduce to multiple cats? So far it appears she’s going to be pretty scared just to see any of the others.

  13. jhofve77
    January 31, 2012 at 8:28 am

    If you have an “incident” you have to start the introduction over *from the beginning*, as if they had never met. If you follow the directions in the article EXACTLY (which, from your comments, you did not), and go SLOWLY ENOUGH (moving to the next step before the cats are ready is the best way to destroy all the progress made to that ponit), chances are excellent that it can be worked out. Three months is nothing. Now it will take another three months, but what’s your alternative? In most shelters it would only take 3 days to euthanize him. Please try again!

  14. Garrett
    January 31, 2012 at 8:05 am

    Understand that sometimes, cats will not get over the initial “bad impression”. We have an 8 yr old female Bengal and we recently adopted a 1 yr old male Bengal as a companion. BIG MISTAKE. We did everything except let them duke it out. It’s been 3 months and we’ve gotten no where. We keep the male in our bedroom and let our female have the house. If we let him out, he charges despite her verbal warnings and all hell breaks loose. We think he is trying to play, but she’s not having any of it. We’ve gotten to the point where the original owners have determined there is no progress being made and want him back to put in a shelter, my wife is in love with him and wants to keep trying, I’m lost at this point, but life was easier, smelled better, and was less violent with just one cat…..

  15. jhofve77
    January 25, 2012 at 12:39 pm

    There are no rules, it just depends on the cats’ personalities. Be sure to closely follow the instructions in this article, and you should be fine.

  16. jhofve77
    January 25, 2012 at 12:37 pm

    If there is no forward progress or there is a problem, back up a few steps until you reach a balance, then proceed SLOWLY forward again. It can take many weeks. Be patient. The cats MUST dictate the pace.

  17. nikki
    January 25, 2012 at 6:18 am

    I have a 2.5 year old de-sexed female and recently introduced a 6 month old de-sexed male into the household.
    I have done the isolation room, scent swapping, site swapping, feeding on opposite sides of the door, supervised play time through a crack in the door and now after 2 weeks have introduced them.

    The new cat is pretty much keeping the new kitty in the isolation room, she just sits outside the door and swipes/ occasionally hisses at him if he tries to come out. They eat their food within a few feet of each other no problems and will eat treats within a foot or so but she won’t let the new kitty explore the house. I don’t leave them together when i am at work or at night time but is this something they will work out or should I back track a few steps?

    Thank you :)

  18. Joyce Laibe
    April 29, 2011 at 4:17 pm

    I am thinking of adopting another cat. I currently have a 3 year old male and was wondering what age and gender cat would be best to adopt. Someone had told me once to get a male cat that is already neutered and older than 4 months. My cat has never been exposed to other cats exept as a kitten. What’s the best option?

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