Introducing a kitten to adult cats prior to introduction to your household, all kittens should be health checked by your veterinarian and tested for FeLV/FIV (a blood test used to detect feline immunodeficiency virus FIV and feline leukemia virus FeLV). Introduction of a new kitten to a household already inhabited by cats can be a challenge.
There are many ways to introduce a new kitten, but in general, gradual staged introduction is the most reliable method. Most kittens are friendly and want to play. Many adult cats are resistant to newcomers. Successful introduction takes the needs of all the cats into consideration. Select a room in your house with a door. It should be a room that is not often inhabited by your resident cats. A bathroom is a good choice. Confine the kitten to the room with food, water, litter pan and toys. This allows the resident cats to smell and hear the new kitten, but not interact directly. The time line is variable, but is often one to two weeks of confinement. This confinement also has the advantage of allowing you to screen the kitten for the development of an upper respiratory infection or URI (sneezing, coughing, runny eyes). This is often self-limiting but is contagious. Many kittens will develop a URI shortly after going to a new home, especially those from shelters.
It is a good idea to place a towel or other bedding in with the kitten, and then leave that object out where they other cats can smell it. Likewise, providing a kitten with an object that “smells” of the resident cats is of benefit. Feeding treats on each side of the door (resident cats on one side, the kitten on the other), is also helpful. Close monitoring of the initial cat-to-cat introduction is essential. Hissing and posturing is normal cat behavior and should be allowed. Tell your veterinarian if you are introducing a kitten into a household with resident cats. Your veterinarian will assist you with the introduction strategies.