Even if the cat you are adopting is good with other cats, there is no 100 for any living being. There is always the possibility of problems when introducing strangers to each other. This goes for humans, dogs and cats too. There are several steps that you can take to reduce the likelihood of problems. Before bringing your new cat home, create a separate “safe space” for him/her. This area should be comfortable and quiet with food, water, a scratching post, a litter box, places to hide, comfortable places to rest, access to natural sunlight, and is safe from other animals.
Your other cats should have their own separate space. Make certain that both areas (the space for the new cat and the space for the other cats) contain multiple hiding places so the cats can easily retreat if necessary. Large cardboard boxes with holes cut in two sides make great hiding places. The second hole allows the cat to escape if cornered by another cat. The boxes will come into play once you start allowing the cats to interact directly, but it can be helpful to introduce the boxes first, so that the cats become accustomed to using them.
Place your new cat in his/her space as soon as she arrives home and spend good quality time with them there each and every day. Play with them regularly and watch them closely for signs of stress or anxiety, such as hiding, aggressive behavior, decreased appetite, and/or excessive vocalization. If you see any of these signs, your cat could be suffering from stress. If the signs persist for more than several days and/or if your cat stops eating, consult with your veterinarian.
If any cat is showing mild signs of stress, give him or her time to acclimate to the new situation. If all the cats appear comfortable in their spaces, place the new cat in a different room (equipped with the same amenities) after two days, and allow your other cats to enter the new cat’s original territory. This will allow each cat to become accustomed to each other’s scent in a non-threatening way. Allow the cats to acclimate to their new areas for a couple days.
Take your time with this process and transition. There is no rush. Like all new relationships, each cat involved will need time to learn the other. Some cats (like people) will need longer than others. Careful observation on the humans’ part is necessary throughout the entire introduction process. Your new furry companion will so appreciate you for it!