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One cat is great, so more cats are obviously better, right?
This can be true! Sometimes adding in 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: the original (the kind that link will send you to), the MultiCat variety, and the newest version, Optimum. Any of them have the potential to help, though the MultiCat variety 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.
If possible, you'll want to also obtain something that smells like your new cat ahead of time. This could be a blanket or towel that they've spent time on. Similarly, if you can get something that smells like your cats (again, bedding or a towel works great) that can help. 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 new cats and you and your cats can begin to recognize the new cat before the new cat comes into the home.
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.
Bringing The Cat Home
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. 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 your and initiate contact. You can offer a few fingers, but present them at a distance without shoving them 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.
Starting the Introduction
During this time, you should be swapping out bedding from the other cats so the cats and the new cat so they can get used to each others' smells. Observe the cats' reactions and do NOT move forward with the introduction if there are any negative reactions to the smell. The cats should be calm when they smell each other.
A lot of 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 a bit 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! 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.
Once the cats are completely calm, heard the resident cats 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! 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.
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.
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.
A lot of introduction guides suggest having cats eat on opposite sides of the door 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. I get the logic about creating a positive association with each other, but eating in groups can actually be more stressful for cats.
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. You may even need to do a double baby gate if needed to block the cats from jumping.
Another option would be harness training each cat, but make sure the cats are comfortable in the harnesses! A good harness option is by the brand Kitty Holster. You'll need to train the cats ahead of time so plan ahead if you are going to use this option.
Let the cats see each other at a distance and consider feeding each of them some treats. For the first look, a brief and distant look is best. 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. As they seem comfortable, consider adding in play time where they can see each other play across the gate.
If there are any signs of upset cats, especially any hissing, lunging at each other, or a cat running away, 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.
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 one.
Regardless of your cats' reactions, I suggest a few sessions with the gate and gradually increasing the time the cats see each other. This allows them to build up a positive association while keeping their fear response low!
Meeting of the (Feline) Minds
Once the cats are fine across the gate, you can have them meet without the gate for the first time. Always have a towel or cushion nearby to 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!
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, 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. 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.
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!
About the author: Joey Lusvardi is a feline behavior consultant and cat trainer based out of Minneapolis, Minnesota. He runs a behavior consultation service, Class Act Cats, where he helps cat parents address a variety of unwanted behaviors. He is available for consultation in the Twin Cities or virtually wherever you are located.