Cat litter training is something that you will want to do right away when you…
This can be a difficult one, and it’s very likely to be time-consuming. Introducing a new cat into a household where there is already at least one other cat will take both time and thought, and some careful actions on your part.
The main thing to remember is that already existing pets will feel somewhat threatened, especially in the beginning. As well as feeling like their territory is being invaded by an intruder (and of course they’re absolutely right), they may feel that you yourself are abandoning them. So through the entire process of introduction, you will need to reassure the first cat (or cats) that you absolutely do still love them. You may in fact need to spend more time with them than you did before, to make sure they continue feeling secure in your affections.
In a similar way, the new pet will be understandably nervous and insecure. This could lead to some aggression, especially toward the existing pet, simply as a matter of a perceived need for self-defense. So you will also have to take time with the new cat, teaching it to feel cared for and secure with you.
The best way to start is to keep the new pet in a single closed location until it gets used to you and that room. Provide all the food, water, and other things it will need, and visit as often as you can, to pet it, talk to it, and even play with it. The two cats may interact a little, by pawing under the door or hissing at each other through it. But once they have pretty much stopped hissing, then have periods where the resident cat is confined to another room and the new cat can come out and explore the home with you. Do this until the new pet appears quite comfortable in the residence.
Then comes the step of having both cats out in the open at the same time. It might help to do this at mealtime, with separate dishes, so they can see each other but have the comfort and reassurance of the food. If they can’t seem to relax enough to eat, confine them again so they feel secure enough. When they can eat at the same time, even with the other cat in the room, allow them some time to remain out in the open together, before confining the new cat again. These times of being out together can increase in length until neither cat needs to be sequestered.
Not all cats will become bosom buddies, but most will learn to coexist quite well. But you must always keep in mind that if they just can’t seem to adjust to each other you may only have two other choices. You will either have to keep them permanently confined in different parts of the house so they have no contact, or you may have no option but to recognize that the new pet simply won’t fit into your household. Rather than put the cats under severe stress, it may be kinder to both pets to find the new cat a different home.
But hopefully, if you introduce a new cat gradually, and be sure to make both pets feel safe and cared for, they will accept each other and ideally become good friends.