Instructions
Take all pets to a vet before any introductions. Some diseases and parasites are easily transmittable.
Set up separate living quarters. The new kitten should be kept in its own room for about a week, while the older cat has access to the remainder of the home. Be sure both animals have access to food, water, toys, a comfortable place to sleep and a littler box.
Show them a new scent. Switch the cats' blankets or toys to get them accustomed to the new smell before they meet each other.
Give them a glimpse. Let the cat and kitten see each other from a distance a few times before they are close enough for contact. You can do this through a window or screen, or you can open a small crack in the door to the room where the kitten has been staying.
Encourage play. Give them a toy they can play with under the door. This way they can begin to bond without the risk of confrontation.
Feed them together. After the cat and kitten have been allowed to see each other and have become accustomed to each other's scent, begin feeding them in the same room. Start at opposite sides of the room and slowly move the bowls closer together.
Take baby steps. Let the cat and kitten stay in the same room, with access to each other, for short periods of time. Gradually increase these time increments.
Expect unpleasantness. Even after gradual introductions, there will be some unhappy reactions at early meetings. The older cat may growl, hiss or swipe at the kitten. The kitten may also show aggression, or it may hide.
Watch them closely. For the first couple of weeks the cat and kitten are allowed contact, do not leave them together without supervision.
Add litter boxes. According to the Humane Society, you should have a litter box for each cat, plus an extra.
How to Bring in a Kitten With a 1 Year Old Cat
Cats can be very territorial -- especially adult cats. Adulthood in cats begins around the age of 1. After this age, pet owners need to be very careful when it comes to introducing new kittens into the home. A proper introduction can go a long way toward improving the relationship between the cats in the future. It can also be instrumental to the safety and security of the young kitten.