Introducing Cats: How To Successfully Introduce A New Cat To Your Resident Cats

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One cat is great, so more cats are obviously better, right? This can be true as long as you go about introducing the new cat properly! Sometimes adding a new cat to the mix can be delightful to you and sometimes the cat will end up being buddies with your resident cat. However, this isn’t always the case and if not done properly, the cats may end up with more problems.

This is true even if you have generally very sweet, friendly cats toward you or other cats. Cats are extremely territorial and a new cat in their space that they are not familiar with can make even sweet cats become not so sweet.

I absolutely recommend adopting cats in bonded pairs if possible, but sometimes that doesn’t happen and you want to add another cat to your household. This guide will help give you some basic steps to help you give your cats the best chance of living in harmony (or at least tolerating each other). If you want more specific advice, I’m happy to set up a consultation to help you figure out how to introduce your cats!

Before The New Cat Arrives

Setting up your space ahead of time is extremely important and can prevent a lot of problems later. In order to get your new cat adjusted to their new home, you’ll need to give them their own separate space.

This space should be quiet, a comfortable temperature, and somewhere any resident cats won’t have access to. It also shouldn’t have any dangerous objects, including plants you don’t want the cat munching on or anything that could injure the new cat, and ideally should be a location you are comfortable spending time in.

Set up the space to make sure all your cat’s basic needs are met in the room. These needs include:

You may also want to consider a Feliway pheromone diffuser to help keep your cat calm in their room. They make three varieties: Classic, MultiCat, and the newest version, Optimum. Any of them have the potential to help, though the MultiCat or Optimum varieties may be your best bet for an introduction. Plug in the diffuser and let it run continuously. It typically takes a few days for effects to be noticeable so you may want to let it run for a day or two before the new cat arrives. It’s better to keep it running than to plug and unplug it or move it between rooms.

You’ll also want to begin familiarizing yourself with cat body language. It will be extremely important later in the introduction process to be able to read what each cat is telling you about their comfort level. I suggest Lili Chin’s excellent guide Kitty Language for an easy-to-follow resource on how to read cats.

Introduce By Scent

If possible, you’ll want to obtain something that smells like your new cat ahead of time as introducing cats can begin before the new cat is even in their new home. This could be a blanket or towel that they’ve spent time on. You can also use a cat bed they snuggled into frequently. Similarly, if you can get something that smells like your cats (again, bedding or a towel works great) to get the new cat until you pick them up, it will help them learn to accept your cats. You can also include a shirt that you’ve worn that smells like you so the cat is familiar with your scent.

Swap the scented objects so the new cat can smell the resident cats and you and your cats can begin to recognize the new cat before the new cat comes into the home.

Make Environmental Cahnges

A few days ahead of time, close off the door to the room so your resident cats are used to not having access to it. You can also use this time to make any changes you need to the main living space so that all cats have their basic needs met. You should have different resources for each cat (see above) set up in different locations rather than lumping them together in one space.

You need at least one of each resource for each cat, though adding an extra is always a good idea. This is particularly true for litter boxes! A good rule of thumb is one litter box per cat plus one extra and at least one on each floor of the house. The litter boxes especially should be spread out and not all put in one location.

Two cats looking at the camera.
Don’t make these cute faces go over the river and through the woods to get to the litter box.

Bringing The New Cat Home

The first step to introducing cats is actually avoiding having the cats meet too early. Bring your new cat home in their carrier and directly to their safe room. Do not try to carry the cat in without a carrier or introduce the cat to the other cats in the carrier. This can be extremely scary for the new cat. Covering the carrier with a towel sprayed with pheromone spray may help the new cat so they don’t see any other cats while helping them stay calm.

Set the new cat’s carrier down in their room and allow them to decide if they want to get out or not.  Never force a cat out and there is no need to do anything like showing your cat where their box is. Let them remain in control. The new cat may run and hide or they may hiss at you. That’s okay! Let them settle in.

You may want to leave the cat alone in the room for a while to settle in and explore. You can go in to give them food and check their water if needed. Eventually, you can go in and sit quietly in the room, preferably on the floor or at the cat’s level. Let the cat come to you and initiate contact. You can offer a finger, but present it at a distance without shoving it in the cat’s face. The cat may sniff you, but be cautious about petting them right away. Start out petting only their chin and cheeks at first for a brief moment if the cat lets you.

Spend time in the room with the cat. As they seem more confident, you can begin playing with them and interacting more and more.

Preparing For The Cats To Meet

During this time, you should be swapping out bedding from the other cats so the cats and the new cat can get used to each other’s smells. Observe the cats’ reactions and do NOT move forward with the introduction if there are any negative reactions to the smell as it could signal a problem with the introduction. The cats should be calm when they smell each other.

A lot of other guides and well-meaning folks suggest that you should do this for a particular amount of time or that you should keep the cat confined for _____ days. I’m not a fan of that approach as every cat is different and every pair of cats is very different. A confident cat may need less time in the safe room and a more timid cat may require longer. For the whole introduction process, you’ll want to listen to your cats.

This means listening to each cat individually. If you have four cats, all four need to be calm before moving forward. If one isn’t, give them a chance to adjust for a bit longer before moving on. Remember, you are introducing cats four times to your new cat so you’re really doing four separate introductions.

Exploring New Spaces And Smells

Once the cats are completely calm at baseline, temporarily heard the resident cat(s) into a separate room and allow your new cat out to explore the main living space. Depending on the size of your space, you may want to do this gradually over multiple sessions as it’s less stressful to introduce a cat to a large space room by room. Allow your cat to explore and get to know their new space.

Ideally, you should also swap the resident cats into the new cat’s room without the resident cats and new cat seeing each other. Make sure you do this in a way that doesn’t scare any of the cats as you don’t want them to be frightened. This will create a negative association between the cats and the spaces or, worse, each other’s scent. Close the door to the new room and let the resident cats smell and explore there. If they are upset by being in the room, you may want to spend time in the room with them.

Side note: For more tips on addressing cats that struggle with being away from you, check out my guide on separation anxiety in cats.

Once they’ve all had a chance to explore, once again swap the new cat into their room and the resident cats into the main living space. You can repeat this a few times to create a colony scent. Creating a colony scent is an extremely important part of this process as it’s a huge part of how cats recognize who is in their group.

It may also be helpful to have the cats on both sides of the safe room door to play with a toy under the door. This allows the cats to build up a positive association with each other and is much better than a commonly suggested method of building a positive association between cats.

Skip Feeding On Opposite Sides Of The Door

A lot of guides on introducing cats suggest having cats eat on opposite sides of the door that separates them or of a baby gate. I actually don’t typically suggest this (except for in a few specific cases for a specific purpose with clients, but that’s a whole blog post in it self) as cats don’t naturally eat in groups. Most of the time, they’re catching small prey that isn’t easily shared.

Another problem I see with clients and feeding the cats near each other is that the cats will eat near each other unless extremely stressed. That doesn’t mean they like each other or will be fine meeting face to face. Eating is a basic need for survival so if the cats don’t have a choice but to eat near each other or are highly motivated to move closer than they’re comfortable, they may put up with being near a cat they aren’t comfortable with.

I get the logic about creating a positive association with each other, but eating in groups can actually be more stressful for cats. Play is a better choice. Plus, one of the most important things you are trying to teach the cats is what to do when the other cat is around. You aren’t really teaching them what to do if the other cat is there by using food. By playing, you’re teaching the cat that they can choose to play with a toy while the other cat is there as the behavior is naturally self reinforcing.

Introducing Cats Visually

Once the cats seem not bothered by the other cats on the other side of the door, you can start letting them see each other. I recommend using a screen or baby gate and making sure the cats do not leap over the gate. There are many options for preventing a jumping cat: full-door length pet gates, extra tall gates, or using two baby gates to prevent jumping. If you have the time and patience, you can consider making your own gate.

Let the cats see each other at a distance and consider feeding each of them some treats after the session. For the first look, a brief and distant look is best. You may even want to let the cats see each other for a few seconds and then end the session or have them only partially see each other. Monitor their reactions closely and if they seem fine, the next time they meet you can let them wander closer. After the session, give all cats some treats, a meal, or play time.

You want to do this a few times and gradually let the cats get to the point where they sniff each other across the gate. If they don’t end up sniffing each other, that’s fine as the more important thing to watch for is that the cats are calm. As soon as they seem comfortable, add in play time where they can see each other play across the gate, but at a distance. This helps teach the cats what to do when they see each other while building a positive association. Again, the key here is at a distance and for short sessions while gradually building time that the cats spend near each other.

Another great option? Clicker training cats is fun and will directly teach the cats how to behave when they see each other. You’ll want to start by training them to do behaviors like sit or coming to you when called without the other cat there, but once they get them down you can try it while the other cat is present across the gate. You can either learn how to clicker train your cat with a training kit or by setting up a session with me for individualized lessons.

End Things At The Right Time

A very important part of this process that may prevent you from ending up as one of my clients: end all interactions before the cats become upset. In other words, do not let the cats keep going until they end up hissing, growling, or otherwise being displeased by each other. If you aren’t sure how long that is, end the interaction early. The goal is not to push them so much as it is to keep them from becoming upset by each other.

If there are any signs of upset cats, especially any lunging at each other or growling, immediately block visual access and close the door. Do not attempt another session until the cats have had a chance to calm down. And absolutely do not use a squirt bottle or punish your cats as you will make the situation worse.

A Note On Hissing

You’ll notice that I mention hissing as being something that signals ending the interaction. It’s not necessarily abnormal to have some cat hissing at first so a few hisses doesn’t mean that things are hopeless. It should lessen over time, but it’s still a good idea to end the interaction early in the beginning so things don’t progress to a full cat fight.

Eventually, some hissing can be okay, but you don’t want to risk it in the beginning. You should also have less hissing as time goes on. Those first few meetings are critical, however, so ending things earlier is better.

Two cats sitting side by side looking up at a human.
 “We learn better when we’re not afraid!” Photo courtesy of Unsplash.

At this point, you may want some help if the cats are not digging each other as it’s easier to prevent a negative association than it is to fix an introduction gone wrong.

Regardless of your cats’ reactions, always use the gate at first and gradually increase the time the cats see each other. This allows them to build up a positive association while keeping their fear response from kicking in.

Meeting of the (Feline) Minds

Once the cats are fine across the gate for a significant amount of time, you can have them meet without the gate for the first time. Always have a towel or cushion nearby to gently separate the cats if needed.

I suggest doing this in a place that all cats can escape if needed and avoiding hallways. An open room is best. Some of the worst places you can do this step are hallways or stairways as they can very easily make the cats feel trapped. That said, the room shouldn’t be too open. The cats should have places to get away from each other so break up the open space with boxes or make sure there are places the cats can climb nearby.

The first meetings should be shorter and then you can gradually let the cats spend more time with each other as they seem okay. Always end each visitation with some rewards such as a meal, puzzle feeder, treats, or play time.

Your cats will hopefully at this point be okay with each other, though always keep an eye on their behavior for signs of stress or fights. Never let your cats “fight it out” as that will make their relationship more damaged and create more work to undo later.

If they do begin fighting, separate them right away and contact a behavior consultant or your veterinarian for advice. Sometimes a cool down period of a few days will be sufficient and they’ll be fine again, but it could also require more intervention. It’s a good idea to get a professional involved to make sure you are set up for success and determine best next steps!

Do I Have To Do This?

I mean, no, I’m not forcing you to. But…

This all seems like a lot of work and I won’t deny that it can be depending on your particular cats. Some cats may take a few days to adjust and some may need a week or two. Other cats can take months to accept each other. It’s understandable that you’d be tempted to just risk it, but it’s a really big risk. Getting cats that are fighting to get along is NOT an easy process and will take you way longer to fix.

In the end, introducing cats correctly is less work than trying to fix a cat introduction gone wrong. This process is way easier to do than a reintroduction!

And seriously, if it seems like a lot of work, I’m happy to help you out!

I hope your new cat, resident cats, and all humans involved enjoy their new home together and you all have many years of happiness ahead!

Two orange cats with tails up in a field of grass walking side by side.

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Joey Lusvardi

Joey Lusvardi CCBC is an IAABC Certified Cat Behavior Consultant and professional cat trainer based out of Minneapolis, Minnesota. He runs a behavior consultation and cat training service, Class Act Cats, where he helps cat parents address a variety of unwanted behaviors. Joey is available for in home sessions locally or virtual sessions wherever you are located!