Cat Introductions 101: It’s All About Patience!

A lot of people expect cat introductions to be “difficult” – after all, cats have a reputation for being solitary creatures, possessive of their territory and resources, right?  Not always!  Think about it – feral cats often live in colonies, in a combined effort to exploit food resources, protect their members, and even communally raise kittens.  So shouldn’t our domestic kitties be able to get along together, living in peace within a family?  Yes!  They can, and they do.

As a volunteer at the local Humane Society, a lot of patrons ask me about adopting a new cat, and what age/sex would get along best with their existing cat of a certain age/sex.  I can tell you that there’s no magical combination – it mostly comes down to personalities.  You will want to consider your existing cat – for example, if she is older, has a mellow personality and is more of a “lap cat”, you probably don’t want to get a one-year-old juvenile that has a ton of energy – the youngster may spend a lot of time aggressively “pestering” your older cat to play, and your existing cat just might not have the patience for that type of energy.  So think about the cat(s) you have, and what kind of cat would match up best – do you want two males with strong personalities who will compete with each other?  Maybe not – you could have fights over resources (food, toys, territory, people) and literal pissing matches (excuse my language!); but that’s not to say that getting two males to live in peace with each other is impossible.  If you have a female with a strong personality, would a more relaxed male cat be a good match?  Perhaps.  You know your cat best – what type of friend would she want, if she could choose one?
We'd all like to see our cats get along like this! (Image from

In addition to considering cat personalities, the other key to success is determining how willing you are to go through a proper introduction, which can be short (a matter of days) or long (sometimes months).  When my cat Jesse was 11 years old, I brought home a new female kitten, Abbey.  Only two days had passed when I woke up to find them curled up together on my bed, Abbey suckling from Jesse’s neck and purring and kneading (even though Jesse is a male).  She still does this occasionally, five years later!  On the other hand, my mother-in-law adopted a mature male cat and had an existing older male cat at home.  Their introduction took about three months, but after a lot of patience, baby steps, and positive reinforcement, these two cats live in harmony in their shared environment.

So how do you integrate a new cat into a family with an existing cat?  What I want you to remember is this acronym:  STOP.  When you want to push the new and existing cats together, STOP and think.  S = Safety: are the cats in a safe situation where they will not hurt each other (or hurt you)?  T = Transform: have you made an effort to change scary situations into ones that have positive associations?  O = Observe:  are you paying close attention to how your cats interact with each other (at all levels of exposure, described below), and are you guiding their introduction in response to what you see?  And finally, P = Patience:  you may need to go slowly; this is perfectly ok!  It’s better not to rush things – the more patience you have, the less stressed your cats will be (both in response to you, and the other cat).  Keep all of these things in mind as we go through the steps for a smooth introduction.  Let’s do this!

1.  Set up a Safe Room for the New Cat.  The first thing you’ll want to do is provide your new cat with a place in which she will feel safe and comfortable.  You can use a spare bedroom, or if you don’t have one, the bathroom – any room with a door or that can be blocked somehow.  Clean the room well, and try to keep your existing cat from spreading her scent in the room prior to the new cat arriving – this will be the new cat’s home for a little while, and we don’t want her to be intimidated by another cat’s scent!  In the safe room, you’ll want to have food, water, two litter boxes, toys, a comfortable place to sleep (a cat bed, or soft blankets are fine, too), a perch (cat tree or maybe a dresser from where she can look out a window), and a place where your new cat can hide (either a box, or a bed to crawl under, etc.).  You may also want to install a pheromone diffuser in the room, which contains the F3 facial pheromone.  When cats rub up against things with their cheeks, they spread this pheromone on objects and other cats/people – it’s a calming pheromone, which can increase a new cat’s sense of security.  When you bring your new cat home, bring her to this room with NO interaction with your existing cats; place a towel underneath the door to prevent new and existing cats from seeing and smelling each other prematurely.  Spend some time playing with your new kitty!  Make sure she settles into her room and knows where everything is.  Don’t forget to play with your existing cats, too (separately, at this point)!

2.  The Nose Knows!  Did you know that cats rely on their sense of smell more than any other sense?  They are able to detect things about their environment – and the cats that inhabit it – from just a whiff of scent that humans are nowhere near capable of detecting!  Cats leave each other “calling cards” through urine marking and pheromone deposits (like rubbing up against doorways and corners); they can tell who’s in heat, how long it’s been since a male has passed through his territory, and many other tidbits of information.  In our situation, we’ll be taking advantage of the cats’ keen sense of smell to desensitize and counter-condition the cats to each other using scent introductions.

Kitty sniffers are extremely sensitive and provide cats with invaluable information (image from

Kitty sniffers are extremely sensitive and provide cats with invaluable information (image from

The first thing you’ll want to do is exchange scents (or do a “scent swap”).  To do this, take a clean sock and rub it gently on your new cat’s face and cheeks, head and neck.  Take a different sock and do the same with your existing cat.  Present the socks with the other cat’s scent on it to the opposite cat – in the case of the new cat, let her smell the sock with the existing cat’s scent, and leave the sock in her room with some treats (positive association right here!).  Do the same with the existing cat.  Watch what your cats do – is there any reaction?  If not, that’s great!  If there’s a negative reaction (hissing, fear or nervousness, for example), you’ll want to repeat this process until the sock is just a sock.

The next thing we’ll do is create a “group scent”, which is a co-mingling of scents from all of the cats in the household, to let the existing cats know that the new cat is part of their group and can be accepted (this process is generally called “allorubbing”, when scents are transmitted from cats rubbing up against each other; we’re just going to do that part for them).  Use a soft brush to gently brush the new cat’s cheeks, face, head and neck, then shoulders.  If the new cat is not used to being brushed, go slowly and gently.  Then present the brush with your new cat’s scent on it to the existing cat and watch how she reacts – let her sniff the brush.  If she reacts negatively, leave the brush with her along with some treats so that she can get used to it.  If she seems ok with the scented brush, brush your existing cat’s face, cheeks, head and shoulders with the brush; but don’t force the brush on her!  If she resists brushing, leave the brush with her to get used to.  If you are able to brush your existing kitty, the brush now has both of your cat’s scents on it.  Take the brush back to your new cat and let her check it out.  If she lets you, brush her to incorporate your existing cat’s scent onto your new cat.  Get the picture?  You’ll want to do this every day until both cats are fine (i.e., indifferent) to the scent-loaded brush, and then continue doing this until the cats are physically integrating with each other (see below).

3.  Gradual exposure + positive associations = kitty confidence.  Next, we’re going to visually introduce the cats to each other and use counter-conditioning to associate the other cat with good things (either treats, playtime, or affection and attention).  In the first step, we’ll let the new cat explore the rest of the house while the existing cat(s) is in another closed room so that they are still separated from each other. Let the new cat explore the rest of the home at least once a day until she appears comfortable and confident in her environment.  Make sure to play with the new cat in the new locations to let her know there’s nothing to fear!

Next, you’ll next want to visually introduce your cats to each other.  To do this, we’re going to have interaction sessions on the opposite side of a closed door; this can either involve toys or treats, but not meals (we don’t want primary resources to have any stress associated with them).  You can use wand toys to stick under the door so that the opposite cat will play with it and associate the door with positive things, or give the kitties treats on both sides of the door (maintaining a comfortable distance from the door).  Once the cats are able to enjoy the play time and/or treats (no hesitation, hissing, growling, etc.), you can graduate to using a gate with a blanket over it (which uncovers varying heights off the floor), or open the door wider and wider so that the cats can see each other while playing or eating treats.  If growling or hissing happens, back off – close the door or lower the blanket or otherwise put distance between the cats.  This is a signal that you’ve moved forward too fast – and that’s ok.  There’s always another interaction session to try again!  Try to stop the exposure before agitation occurs – end the exposure on a positive note.  Progress will be made, even if it happens slowly.

You’ll want to get to a point where the cats can be in the same area together, not separated by a barrier, without growling, hissing, “puffing up”, or getting agitated.  Again, toys and treats are good options for helping the cats enjoy their shared time together; playtime can include catnip mice, wand toys, food puzzles, affection…whatever the cats like (it might take two people to keep the cats involved, one for each cat).  And for those tough cases, there are other things you can try to help get the cats relaxed around each other, like clicker training (but you’ll want a professional to help you with that).  Supervise the cats when they are together until there’s no need to create a diversion from each other – if the cats can hang out together in the same room without getting upset, you’ve come a long way!  Congratulations!

4.  Stuff happens.  Now, it probably won’t all be a bed of roses.  It is likely that there will be some growling, hissing, and perhaps even a kerfuffle or two (you should know how to safely break up a cat fight – put a pillow between the cats or scoop one cat up using a blanket).  As I said before, STOP.  You may have moved forward too fast – take a step back, and try again tomorrow.  This is a process that can take a while.  But don’t give up!  Maintain the group scent; use positive associations with treats and playtime; and try to always end on a positive note – before any agitation starts.  Baby steps.  Kitten steps.  Cat introductions are not always easy, but you will get there!  And if you have any problems or questions, you can always contact me for advice.  That’s what I’m here for!

Cat Introductions 101

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Marci and Abbey

Dr. Marci L. Koski, CFTBS, CFTPB

Certified Feline Behavior & Training Consultant


LeeAnna Buis, CFTBS

Certified Feline Behavior & Training Consultant

Fear Free Certified Animal Trainer

Fear Free Certified Animal Trainer

Winner of the Women in the Pet Industry's 2017 Advocate of the Year Award

Marci Koski

Dr. Marci is a certified feline behavior and training consultant, with specialized and advanced certificates in Feline Training and Behavior. She started Feline Behavior Solutions to keep cats in homes and out of shelters as the result of treatable behavior issues. She believes that the number of cats in shelters can be greatly reduced if guardians better understand cat behavior, and learn how to work with their cats to encourage desired behaviors instead of unwanted ones. Dr. Marci’s family includes her four feline companions and her very patient, understanding, and supportive husband.