How To Introduce A New Cat To Your Existing Cat

How To Introduce A New Cat To Your Existing Cat

When the time comes to introduce a new cat to your home, it can be such an exciting and rewarding experience. But if you already have other cats at home, it does require a little preparation and thought.

In the cat world, as in ours, first impressions count. So how can you make sure your cats start their relationship off on the right foot? Is there anything you can do to improve the chances of your cats getting on?

If you’re still wondering whether a new cat is the right choice for you, you might find it handy to take a look at last week’s post – ‘Should I Get Another Cat?’. It explores the science behind whether cats prefer to be together or alone, asks whether males or females get on better together, and reveals whether kittens or adults are easier to introduce.

How to introduce a new cat to your existing cat


“When introducing a strange cat to an existing group, some degree of familiarity must be established before the cats are allowed to directly encounter each other.” (Crowell-Davis, S. L. et al. 2004)

In feral cat colonies, cats build up friendships gradually over time. It takes multiple gradual encounters to for a stranger cat to become accepted into the group, and treated as ‘friend’ not ‘foe’. (Crowell-Davis, S. L. et al. 2004).

The key to ensuring a successful introduction between your existing cat and new cat is replicating this ‘gradual friendship’ process inside your home. Here’s the method currently recommended by the College of Veterinary Medicine at the University of Georgia (adapted from Moesta, A. & Crowell-Davis, S. L. 2011).


  • Before you introduce a new cat to your home, set up a room in your house with everything your new cat will need. This will include their food, water, a litter box, bed, hiding places that are off the ground, and toys. (You can take a look at our post, ‘How To Prepare For A New Cat or Kitten‘ for a full checklist of what your new cat will need)
  • Restrict your new cat to this room when they first come home.


  • Take an old sock or towel and rub it all over your new cat’s head, tail and sides to pick up its scent. Then leave the ‘scented’ sock or towel in the area that belongs to your existing cat.
  • Do the same thing in reverse, picking up the scent of your existing cat and leaving it in the room that you’ve dedicated to your new cat.
  • To help things along, you can also swap items that have naturally picked up each cat’s scent, such as their bedding.


  • After a few days, let your cats see and hear each other for the first time. You can do this by opening the door of your new cat’s room just an inch. Alternatively, if you have one, you can keep them on opposite sides of a baby gate or screen door.
  • Monitor them closely for any signs of aggression, e.g. flattened ears or hissing.


  • If the ‘see and hear’ encounters are not aggressive, you can bring the cats together under supervision. The safest way to do this is with both cats wearing harnesses, so that if any fights break out they can be easily diffused.
  • It’s important to get both cats happy with harnesses while they are still separated. Once both cats are completely comfortable with wearing a harness, attach a house leash and bring both cats together cautiously.
  • If at any step of the process you see one or both of the cats showing signs of aggression, move back to the previous step for a while before trying again.

How to introduce a new cat to your existing cat


After you’ve completed the gradual introduction phase, there are a few additional things you can do to help your cats get on.

The first thing to do is to take note of the dominance structure that’s been established in your house. Which of your cats is dominant and which is subordinate?

A subordinate cat will often (but not always):

  • Look away and turn its head away, when it encounters the dominant cat
  • Lean back and lower its ears a little when it is confronted by the dominant cat
  • Crouch, lower and curl its tail and flatten its ears against its head if the encounter escalates
  • In the most extreme encounters, the subordinate cat will roll over.

A dominant cat will often (but not always):

  • Approach the other (subordinate) cat with stiffened limbs, stiffened ears and with the base of its tail elevated and the remainder of the tail drooping.
  • Stare at the other cat, sometimes with its head wagging slowly from side to side.

(adapted from Moesta, A. & Crowell-Davis, S. L. 2011)

It’s worth pointing out that none of the above are cause for concern – they’re just the way our cats have developed of sharing resources and avoiding fights. As we saw in last week’s post, where a cat is in the pecking order doesn’t seem to have an impact on their stress levels.

But it is worth knowing which cat is the ‘top cat’ and which is the underling, because it means you can treat them accordingly. For instance, it is recommended that you feed your dominant cat before the subordinate one:

“It is important to manage the cats so that the dominant status of the highest-ranking cats is acknowledged e.g. by feeding them first”
(Crowell-Davis, S. L. et al. 2004)

Some dominant cats will be fairly easy going, and let the subordinate cats share their resources. But others will attempt to control the key items in their territory, including food and water bowls, litter trays and even access to the cat flap for outdoor cats.

To avoid this, ensure that all of these elements are available in plentiful supply. The general rule is that if ‘n’ is the number of cats in your household, the number of items you need is always ‘n+1’. So if you have two cats that means 3 litter trays, 3 food bowls and so on. It is also helpful to separate those objects around the house. Otherwise, if they’re too close together, your dominant cat will still be able to control them all!

How to introduce a new cat to your existing cat


Oh Feliway. I have bought a LOT of Feliway, and another product called Feliway friends in my lifetime. It is seriously expensive, and I have never really been sure if it’s having any sort of effect. We’re written a detailed post about pheromone diffusers which is well worth a read: (Do Pheromone Diffusers and Sprays Work?)

But let’s just take a quick look at whether they can help with introducing a new cat to an existing cat.


Studies have found that Feliway reduces cat stress overall, and makes a cat more willing to explore an unfamiliar space (Pageat, P & Gaultier, E. 2003). Because of this overall stress-reducing effect, it can help keep cats calm while a new cat is introduced:

“Installing an F3 diffuser (Feliway, CEVA Animal Health) will increase the familiarity and security, and should be provided for the newcomer and resident cats in their respective areas of the house.”
(Rodan, I & Heath, S. 2015)

Feliway recommend that you plug diffusers in 24 hours before your new cat arrives, so that the pheromone can build.


As for Feliway friends, there no peer-reviewed evidence that it helps diffuse conflict. There is one very scant description of a pilot study, not peer reviewed, which reported mild reductions in aggression. But until bigger independent studies have been done it’s hard to say whether it really works.

The unsatisfying conclusion is that Feliway will probably help a little during the early days of the introduction, but when it comes to Feliway Friends you will just have to try it and see. I would be remiss to not mention that doing so is quite a financial investment. Here in the UK where I am Feliway costs around £15 ($19) for a plug in diffuser and 48ml refill, so it certainly isn’t cheap!

Ultimately, it’s up to you. I’d love to hear what your experiences are if you have chosen to use pheromone diffusers during a cat introduction. Did they work? Did they help diffuse tension? And do you still use them now?




Leili x

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