Free-ranging and feral cats lead complex and busy lives. They maintain far larger territories than most people realize, and these territories often contain a variety of environments, such as forests, farmlands, urban gardens and yards. Within these territories, cats explore, hunt and scavenge for food alone. They only occasionally interact with other cats. They don't live in groups or even pairs, and they don't seek out contact with other cats. In fact, they actively avoid it. Considering this natural behavior of cats, it isn't surprising that it can be very difficult to introduce a new cat into an established cat's territory, even when that territory is your home.
If you're bringing a new cat into your home, be patient. The introduction must be gradual. Following the initial introduction, it can take a very long time for a relationship to grow. It takes most cats eight to 12 months to develop a friendship with a new cat. Although some cats certainly become close friends, others never do. Many cats who don't become buddies learn to avoid each other, but some cats fight when introduced and continue to do so until one of the cats must be re-homed.
If your resident cat becomes aggressive when she sees other cats outside your home, you'll probably have a difficult time introducing a new cat into your household. If your cat has lived harmoniously with other cats in the past, the odds are good that she'll adjust to a newcomer. However, it's impossible to predict whether or not any two individual cats will get along.
Unfortunately, there are no reliable guides for deciding the best matches among cats. Some cats are very social and enjoy living with other cats, while others prefer solitary lives. The individual personalities of the cats are more important than any other factor, such as sex, age or size. Be aware that the more cats you have, the higher the likelihood that there will be conflicts among them.
How to manage introductions
Step 1: Controlling first impressions
The first impression a new cat makes when she meets your resident cat is critical. If two cats display aggression during their first meeting, this may set the mood for their future relationship. For this reason, it's best to separate your resident cat from your new cat when you first bring her home so that you can control their initial meeting.
The two cats should be able to smell and hear—but not see or touch—each other. Each cat should have her own food and water bowl, litter box, scratching post, bed, etc. Feed the cats near the door that separates them so they learn that coming together (even though they can't see each other) results in a pleasant experience. In addition to regular cat food, feed the cats extra-special treats near the door as well, like tiny pieces of tuna, salmon, cheese, chicken or liver.
After two to three days, switch the cats' locations so they can investigate each other's smell. This also allows the new cat to explore a different section of your home. Some behaviorists suggest rubbing the cats separately with the same towel to intermix their scents. First gently rub one cat with the towel. Then rub the other cat. After the towel carries both cats' scents, bring the towel back to the first cat and rub her with it again. After a few more days, play with each of the cats near the door. Encourage them to paw at toys under the door. Eventually the cats may play "paws" under the door with each other.
Step 2: Letting the cats see each other
After a week or so, assuming that you see no signs of aggression at the door (no hissing, growling, etc.), you can introduce the cats to each other. One method is to replace the door with a temporary screen door so that the cats can see each other. If you can't use a screen door, you can try using two baby gates positioned in the door jam, one above the other.
Ask a friend or family member to help you with the introduction. Have one cat and one person on each side of the door, and start the introduction by setting each cat down a few feet away from the screen or gates. When the cats notice each other, say their names and toss treats to them, aiming the treats behind them. Over the next few days, continue to encourage feeding, eating treats and playing near the barrier, gradually offering the cats' meals, treats and toys closer to the screen.
Step 3: Letting the cats spend time together
The next stage is to permit the cats to spend time together without a barrier between them. Supervise these initial face-to-face interactions carefully.
It's good to bring the cats together when they are likely to be relatively calm, such as after a meal or strenuous play. Keep a squirt bottle handy in case the cats begin to fight. As the cats become more familiar with each other, allow them longer and longer periods of time together. If one cat spends most of her time hiding, or if one cat continuously harasses and pursues the other, please consult a professional.
If you're bringing a new cat into a household with multiple cats, introduce each resident cat to the newcomer individually. After each of your cats has met the new cat one-on-one, you can start to allow all of the cats to mingle as a group.
Your cats will be more likely to get along if they're happy in their environment. Look at the layout of your home. Make sure there are plenty of hiding spots for your cats. Some like to sit up high, on shelves and on kitty condo perches. Frightened cats, on the other hand, tend to hide under and behind things, so make sure you provide spots at floor level as well. Place food, water and litter boxes out in the open so your cats don't feel trapped when they access these resources. Make sure you have a litter box for each cat, plus at least one extra.
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