Introducing a new cat or kitten to your cats

Posted by Jennifer on October 6th, 2009

kittensYou’ve adopted a new cat or kitten, and want to know how to best introduce him or her to other cats in your home? Depending on their age and personalities, you may take days or months to fully integrate your new cat or kitten to your family pets. Below are some guidelines and helpful tips to get your new feline friendship off to a good start, and hopefully on their way to becoming best buddies for the rest of their lives! (We use the word “cat” below, but you can substitute “kitten” if that applies.)

Generally it’s believed the easiest introduction is when the new cat is younger, smaller, and of the opposite sex, but it really depends on the personalities and experiences of the felines involved. Neutering/spaying of all cats to be introduced is essential, ideally 2-4 weeks before the introduction, so the hormones levels have time to subside.


Confine the new cat to one room with its litterbox, food, water, and a bed. Feed your current cat(s) and the newcomer on either side of the door to this room. Don’t put the food so close to the door that the cats are too upset by each other to eat. This will help to start things out on the right foot by associating something enjoyable (eating!) with each others’ presence. Gradually move the dishes closer to the door until the cats can eat calmly directly on either side.

If you have adopted the new cat from an environment (like a shelter) where it was exposed to sicknesses it could be incubating, follow the recommendations of your vet for the duration of this isolation.  Typically, for the most common sickness (Upper Respiratory Infection), it will need to be 7 to 10 days.  That may seem like a long time, but in addition to keeping your resident cat healthy, the new cat will have a chance to get adjusted to his/her environment’s sounds and smells. The chances that the first face to face introduction with your resident cat(s) will go well are improved – which is very important!


After the 7-10 day isolation period is done, and your new cat is healthy, you can progress to these steps. Progress only when all cats are OK with each other during each step.

1. Switch sleeping blankets between the new cat and resident cats so they have a chance to become accustomed to each other’s scent. Also put the scented blankets underneath the food dishes.

2.  Use two doorstops to prop open the door just enough to allow the cats to see each other (an inch opening) but not get out, and repeat the feeding nearby process.

3. Put the new cat in a secure cat carrier, and open the door so the resident cat can come in and sniff all around the new cat’s room and new cat in carrier.

4. Confine resident cats in another room, and let the new cat explore the rest of the house. This switch provides another way for the cats to have experience with each other’s scent without a face to face meeting. It also allows the newcomer to become familiar with its new surroundings without being frightened by other animals.


The final moment – the first full meeting!  Open the isolation room door and calmly observe. You may want to have a water squirt bottle in one hand, and a blanket in the other, just in case you need to intervene in a sudden attack. Playing calming music or talking in a calm friendly voice to the cats will help YOU to feel less stressed, which will help the cats too! Hissing, puffy tail posturing, growling are normal, but should be minimal if you have taken the time to follow the steps above as suggested.  It may be that the first meeting is only a few minutes if the hissing/growling starts to escalate.

You want to TRY to avoid any interactions between the cats which result in either fearful or aggressive behavior. If these responses are allowed to become a habit, they can be difficult to change. It’s better to introduce the animals to each other gradually (five minutes more each day) so that neither cat becomes afraid or aggressive. You can expect mild forms of these behaviors, but don’t give them the opportunity to intensify. If either cat becomes fearful or aggressive, separate them, and you may have to take a step or two back (back to feeding on either side of propped open door for example) and slowly move forward when they’ve calmed back down.

Cats can make lots of noise and roll around quite dramatically without either cat being injured. If small spats do occur between the cats, you should not attempt to intervene directly to separate the cats. Instead, use a spray bottle to squirt water on the cats in order to separate them (or if that doesn’t do it, trying to cover and wrap one up in a blanket to get them separated). Give them both a chance to calm down before re-introducing them to each other – like a day or more. Hopefully, none of this will be necessary, but if so, be confident that while cats can take weeks to months to get adjusted, most cats can learn to get along, if not become the best of friends.

Tips for after the first introduction

  • keep the second litterbox in the isolation room even after the cats are out together – if you want to move it, do so gradually a few feet at a time to the new location
  • clean all the boxes more frequently
  • make sure that none of the cats is being “ambushed” by another while trying to use the box
  • keep the resident cat’s schedule as close as possible to what it was before the newcomers appearance.
  • calming products like Rescue Remedy and Feliway spay (available at pet supply stores) can help de-stress cats
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