Wondering how to introduce cats with the best chance of success? Bringing another cat home can be a stressful experience, not just for the new cat, but also for the current, resident cat(s). Given that cats are such territorial creatures, most newcomers will be met with trepidation, and a “threat until proven otherwise” viewpoint from the resident cat.
A proper introduction process is essential to ensure the best chance of a harmonious household. Now, there are those lucky guardians who just seem to let the cats be together from day one and they become best friends! This does happen in some cases, but I cannot in good conscience recommend this approach. One fight in the early stages of getting to know each other is all it can take to ruin the chances of a potentially good relationship.
A proper introduction can give the relationship the best chance of blossoming, and the two (or more) cats becoming friends (or at least, acquaintances)!
So, how do we introduce two cats? The science is quite simple. Without getting too technical, this is what we are doing:
Using the behavioural processes of desensitisation and counter-conditioning, we want to expose each cat to the other, starting with a very low intensity and gradually building, all the while rewarding each exposure and creating positive associations with each other using treats.
There are three phases to the basic introduction, with some supplementary activities to do throughout the process.
1. Complete separation (can’t see each other, but will be able to smell each other)
2. Visual access through a barrier
3. Complete access
• Scent swapping
• Space swapping
Let’s go through these in a bit more detail.
Before you bring your new cat home, a “Sanctuary Room” will need to be set up that the newcomer will live in for a few days/weeks. The room will need to have the basics, as well as be enriching (e.g. food, water, litter, scratching post, cat tree/tower, soft music, Feliway spray etc). This room should be a haven for the new cat, and give them time, in relative comfort, to get used to their new surroundings (sounds, smells etc).
Once you bring the new cat home and put her in her new sanctuary room, the resident cat will undoubtedly smell her and be aware of her presence. Try to get the new cat in without the resident cat noticing.
This may cause some negative behaviours such as hissing or posturing around the sanctuary room door. This is ok and is normal. After a few days, or even a week, the resident cat should be desensitised enough that he’s no longer behaving negatively near the door. If he is, you may need to wait a few more days, or work on a counter conditioning procedure with a behaviourist.
Once both cats are relaxed and no longer showing any negative behaviours in general, it’s time to begin the second phase (though remember that there are supplementary steps – scent swapping and space swapping which can happen before now – explained a bit further down).
For this step, you’ll need to find a barrier of some sort that you can use to block the doorway but can be seen through. If you’re handy, a cheap screen door is best, but otherwise a piece of wooden lattice or wire panel from the gardening section in Bunnings or other garden/hardware store can work quite well too. You can put some heavy duty stick- on hooks either side of the door for the panel to hang on.
This step will also be easiest if you have another person to help. If this isn’t possible, I’ll detail another way at the end.
The idea here is to start exposing the cats to each other visually, while pairing the experience with good things (tasty treats).
There are two aspects to this step to be aware of – distance and duration.
Essentially, one person should be in the room with the new cat, and another outside the room with the resident cat, with some treats handy. The best type for this exercise would be those creamy cat treats that come in a tube sachet. This makes it easier to control the cats’ direction and keep them occupied for longer.
You may think that as soon as you open the door, the cats are going to see each other and go towards each other, despite the treats. To minimise the chance of this happening, do these sessions before a meal and after a play – this way the cat is hungry and happy, and the treat will be more rewarding than the other cat!
Distance the cats as far as you can. The new cat in the room behind the barrier, and the resident cat three to four metres away outside the room if possible. The person who is with the new cat should open the door so that both cats can see each other, immediately treat both of them, and close the door again. The whole process should take about 5 seconds. Do this again maybe five to six times, and that’s it for that day.
See what’s happened here? Every time each cat saw each other, they got a treat! This is known as ‘counter-conditioning’. This process is aiming to “pair” the sight of the other cat with tasty treats, so that every time they see the other cat, good things are happening!
The next day, keep the same distance, and open the door for a bit longer, maybe 10 seconds. Each day, increase the time until you get about 20 seconds with the door open and each cat is staying with you both, getting treats. This is why those tube sachet treats are good – you can keep the cat occupied for longer by controlling the rate that the treat is pushed out.
Once you’ve built up to 20 seconds, you can move a bit closer by about half a metre. Reset the time to 5 seconds and keep building on that duration again. Repeat the process – build up to 20 seconds, move closer and reset the time back to 5 seconds. Eventually, you should be able to have the two cats about a metre apart either side of the barrier without any negative behaviours (focused on treats instead!).
If you do end up moving too fast and some negativity happens, you must finish the session for that day, and pick up again tomorrow at the previous distance/time.
Once the cats are completely ok with visual access, you can just leave the door open permanently with the see-through barrier up whenever you are home. This will further help the desensitisation process.
This step can be quick, or it can be painfully slow. The aim is to stay just under the threshold where the cat breaks away from the treat and moves toward the other cat (especially with negative body language). As humans we get impatient so inevitably this tends to happen. Don’t feel bad, just pick up the next day at the previous distance/duration and stay on that level for a bit longer.
As you can see, the above process takes two people. If this isn’t possible in your situation, you’ll need to start using meals rather than hand-treating. I’m not a huge fan of getting cats to feed in sight of each other, but it can help control their location, allowing for the desensitisation/counter-conditioning process.
Just keep in mind that cats are naturally solitary feeders, so if we feed them too close to each other, we can make it worse by creating territorial tension. So don’t get closer than 2 or so metres from each other.
Start off with each cat as far away as possible. Put both bowls down and then stand by the door, using the same process as above – open for 5 seconds, close. Over several sessions, build up to 20 seconds (or as long as it takes to eat the meal), then the next session move them slightly closer and reduce the time back to 5 seconds.
What some clients have had success with is feeding the new cat in the room as far away as possible from the door, and then doing the hand treating process with the resident cat, at the door (behind the see-through barrier) as this allows you to control the amount of time the door is open.
This final phase will mirror the previous phase, just without a barrier in between. This should go a lot quicker since you’ve already built a solid “relationship base” with the previous phases (and supplementary steps discussed shortly).
You’re going to do the same thing as the last step, but without a barrier. It’s better to be safe than sorry so keep a blocker (like a large piece of cardboard), and a blanket nearby to safely stop any violent breakouts.
Start again at a longer distance with a short duration. Open the door, treat both cats, then close after 5 seconds. Gradually decrease the distance and increase the duration until both cats are happy to be near each other, receiving treats. Once this is done, you can start to let them have free access to each other for small periods of time (30 seconds or less) in the same room.
If you don’t have a partner to help with this step, use the same principles as the previous step (meals).
If it looks like a fight is going to break out, distract or block the cats to stop an incident from progressing. Gradually build on the duration until both cats are happy to be in the company of the other.
Gradually allow them to sniff each other. But at this stage make sure that all interactions are supervised. Over time, as the sessions become longer and longer, you’ll be able to trust the cats to tolerate each other unsupervised.
These activities are just as important as the other phases of the process, and will help it go a lot quicker. They can start after the first few days of the new cat coming home (give her a few days to calm down and get used to her surrounding first) and continue throughout the entire introduction process.
What we are trying to do here is get each cat used to (or even excited about) the scent of the other.
Use a clean cloth or sock to rub one cat around their face and neck. This needs to be a positive process so don’t force it if either cat doesn’t want any “affection”.
Then go and place the cloth in the other cat’s territory – put it on the floor in a non-threatening spot, away from any important resources (food, water, cat trees etc).
Ideally the other cat will come and sniff the material. If there is negative body language (hissing, posturing etc), it’s a sign we’ll need to take the introduction slow. If there is indifference or positive interest, this is good. We can further make this a good experience by putting some treats around the cloth. This creates positive associations with the other’s smell.
Repeat with the other cat (use a fresh cloth), and do this daily.
Basically, this activity simply means swapping the cats and putting them in each other’s space for some time. This further allows each to get used to the smell and presence of the other. They will likely want to use the litterbox and rub up against things in the other’s territory to combine scents – this is a good thing and should be encouraged.
You may need to wait a bit longer to start this, depending on how eager/confident the new cat is to come out of the room. If she is an anxious cat, she should never be forced out. Instead, for the first few days it’s better to put the resident cat in another room, and open the door for the new cat to explore on her own first. Once the new cat is comfortable in the new territory, it will be easier to sneak the resident cat into the sanctuary room and close the door.
Space swapping can go for as long as you like, ideally daily. It needs to be a positive experience so if either cat shows anxiety or other negative behavior, it’s time to stop and put them back.
This is like a graduation of scent swapping. It can be surprisingly effective and should only be done if both cats like to be groomed/brushed/pat without stress.
Affiliative cats in a colony or domestic situation inadvertently build up a ‘group scent’, which is a collection of all the scents of the group. It’s built up naturally by rubbing against each other, allo-grooming, sleeping in the same spots, using the same scratchers etc. Each cat in the group will then have this group scent on them, which is an identifies them as a member – kind of like a gang tattoo!
We can use this concept and give the process a little bit of help. It’s very powerful when a cat can smell themselves on the other cat. It makes them think, “Oh you must be part of my group because I can smell myself on you”.
All you need to do is use the same brush or piece of material to brush/rub each cat around the face and neck (where the friendly pheromones come from). Though, again, this needs to be a positive process and should not be forced if the cat doesn’t want it. A cat who is negative towards the smell of the other should definitely not be part of this process. Make sure that you’ve progressed through the basic scent swapping with no negative behaviours before considering the group scent facilitation technique.
If it’s accepted by the cats, it can actually be used ongoing for maintenance after the introduction has been done. I’m aware of circumstances where clients need to keep this up every day or few days to maintain the harmony in the house, especially with cats who aren’t particularly affiliative towards each other (don’t use the same beds, sleep with/near each other, allo-groom etc).
Phew, there you go, the formula for a successful cat introduction. It may sound like a lot, but it’s worth it in the end. Try not to get too impatient, and only progress as quickly as the cats allow. A few quiet hisses here and there isn’t something to be too worried about, but clear negative behaviour and obvious stress means you might be going too quickly.
If you have any questions about the process, or your own introduction stories, let me know in the comments!