The second cat will not be made to feel welcome by the first cat
Cats are notoriously territorial and will act in a bad tempered way when they first catch sight of the second cat. So do not be surprised when you bring the new cat into the home, to find your normally mild, friendly first cat turning into a bully. He may hiss, growl and do all in his power to let the new cat know that he is invading his personal territory, in much the same way dogs warn off other dogs that come too close to their home. There will not be a friendly welcome. The first cat will be protecting his territory and telling the second cat in no uncertain terms to leave.
Keep the two cats separate
In order to lessen the trauma of the new cat as he settles into his new home environment, you will need to keep him apart from the first cat at first. This may not be easy, as the first cat is bound to be very curious about the new “intruder” and will try to seek out the new cat for a confrontation. An effective way to handle this situation is to keep the new cat apart from the first cat, preferably in the vicinity of the master bathroom and bedroom. Check up on the new cat periodically and see that he is not distressed. He may not be used to being shut away on his own. But hopefully, it will only be a temporary measure until the first cat gets used to the new cat. If the first cat likes to go outside for much of the day, you can use this to your advantage and let the second cat walk freely around the house until the first cat comes back home. Repeat this procedure for a few days.
Gradually introduce the cats
Cats will not take to each other straightaway, but will need time to get used to one another. The new cat will undoubtedly feel threatened by the new cat in the home. On the other hand, the new cat may want to get to know the first cat, but may not be able to do so for a few days. When a few days have elapsed, gradually bring the two cats together. Watch them as they interact together in the same room and make sure that you can remove the new cat if the first cat tries to attack the second cat. It will not be long before they can both be in the same room together without hissing and growling at one another. The longer you have had the first cat, the harder it may be for him to accept the new cat in their home. Be patient, as it will not happen overnight.
Separate beds, toys and food bowls
Try to keep each cat’s bed, toys, and food bowls separate from one another. It will make it easier for each cat to still feel that they have their own sleeping quarters, toys that are familiar to them and food bowls that are not shared. Once the cats become accustomed to one another, it may be possible for them to share, or it may not, depending on the animals. But do not force this upon the cats right away. They need to gradually get to know each other. The first cat will need to overcome his initial feelings of resentment and insecurity before he can move on and accept more changes in his life. The smaller the changes, the easier it will be to make a smoother transition from one cat to two.
Treat the cats equally
The first cat will hold a dearer spot in your heart because he has been with you longer, but that does not mean that you cannot still do your best to treat each cat equally. Reassure both cats that you care for both of them by praising them and stroking them. If one usually sits on your lap, try to encourage the other to also do so at some other time. Cats are jealous animals. If you doubt this, then watch the reaction of the one cat as you lavish attention on the other and you will see them staring at you and the other cat. They may even walk by and swat the cat sitting on your lap!
Introducing a second cat into the home is not an easy process. The first cat will not like it at first, but over time, he will begin to tolerate the second cat. They may even grow fond of one another and serve as good companions.