How Should I Introduce My New Cat to My Existing Cat?

Q. We’re adopting a second cat. What’s the best way to introduce the new cat to our established cat?

A. Many cats enjoy the company of their own kind, and many pet owners are happy to accommodate them: Households with two or more cats are more common than those with more than one dog. But the introduction process needs to be handled with patience in order to ease a new cat into the established cat’s home with a minimum of stress for everyone.

Before you bring your new cat home, a visit to the veterinarian is in order. You’ll want your new pet checked for parasites such as ear mites and contagious conditions such as feline leukemia and ringworm. If your new cat hasn’t been spayed or neutered, it’s best to take care of that now as well. Meanwhile, you can be setting up your home to best handle the introductions.

One thing I’m very keen on with cats is the use of pheromones to calm them during their most stressful times, such as trips to the veterinarian, a move to a new house and the introduction of new pets. These synthetic compounds mimic those produced by mother cats to relax their kittens. They’re widely available in many formats, including room diffusers. I use so much of these products that it’s practically an after-shave for me — and my feline patients love me for it.

Both your established cat and your new cat will likely enjoy your liberal use of pheromones; use them in the room you’ll be preparing as the temporary new home for your new cat. This room should also have food and water bowls, and a litter box and scratching post that needn’t be shared with your established cat. This will be your new pet’s home turf while the two cats get used to each other’s existence.

Now that you have pheromones everywhere and a room set up for the new cat, it’s homecoming time. Bring the new cat home in a carrier and set him in the room you’ve prepared. Let your resident cat discover the new guy and don’t be discouraged by initial hisses on either side of the carrier door. When the new cat is alone in the room, close the room door and let him out of the carrier. If he doesn’t want to leave the carrier at first, let him be. Just leave the carrier door open and the cat alone.

Maintain each cat separately for a week or so with lots of love and play for both, and then on a day when you’re around to observe them, leave the door to the new cat’s room open. Don’t force them together. Territory negotiations between cats can be drawn-out and delicate, and you must let them work it out on their own, ignoring the hisses and glares. Eventually you can encourage them both to play games with you, using interactive cat toys. And slowly feed them in ever-closer proximity.

While some cats may share food and water bowls, and some may share even litter boxes, don’t count on your cats being the sharing kind. In fact, feline behavior experts recommend maintaining one more clean cat box than you have cats, just to be sure no one starts thinking outside the box.

Your cats may become such good friends that they nap together and groom each other. Other cats will always keep their own personal space, while others may establish their own territory — one upstairs, one down, for example. All of these results are normal, and it’s up to the cats to decide how best to get along. Let them be, and they may well end up as good friends months down the line.