Do you know how to introduce new cats to your existing kitties? According to the AVMA, most cat-loving households in the United States share their home with more than one cat. But adult cats instinctively distrust strange felines, so how do you keep the peace introducing cats? Why do cats get so upset?

Back in the day, wild cats walking up to strangers risked getting eaten. That removed clueless kitties from the gene pool. Today, most domesticated cats react with a “stranger danger” mentality when faced with unfamiliar situations. Proper preparations help keep the fur from flying during cat introductions, whether you need to know how to introduce a kitten to cats, or adult cats to each other.

The Importance of Cat Introductions

Cats thrive on routine and become stressed when something changes in their environment. Just like people, different cats have a variety of personalities. Christopher Columbus cats enjoy adventure while Shrinking Violet types shiver and hide if you rearrange the furniture. Recognizing your cat’s personality helps you understand how to plan to introduce new cats.

Prime kitten socialization occurs between 2-to-7 weeks of age. Kittens taken too early from mom-cat and siblings don’t learn proper cat communication and social interaction. That means you must understand how the cats communicate and act as a kitty interpreter. These cats may require months rather than weeks of introduction to accept new cat friends. Properly socialized cats more readily accept new cat friends. Introducing two well-socialized adult cats takes 2-to-6 weeks. Introducing kittens to cats can happen more quickly.

Cats often generalize an experience (good or bad) and thereafter, just the sight of the other cat can trigger a similar response. That means a scary cat introduction that causes fear, anxiety, or stress can prompt hissing, growling, chasing behavior. That not only delays acceptance of your new cat. A bad experience during a cat introduction also could program the cats to repeat the bad behavior each time they see each other.Introduce cats slowly. If cats act fearful or aggressive, go back a step. You can always speed up how to introduce new cats when things go well.

How to Introduce Kitten to Cats

Until they reach a year old, a kitten’s normal curiosity outweighs her instinctive stranger danger reaction. Also, adult cats feel less threatened by kittens. Cats love territory and want to own their environment, so an adult interloper threatens that. When you introduce a kitten to adult cats, babies won’t threaten these territorial concerns. Adults usually have an innate tolerance for youngsters. By learning how to introduce your cat to a kitten, you set both cats up for success long-term. Smell, sounds, and sight of the interloper increases cat stress. Cats identify friend from foe by scent, sound, and behaviors. That’s why even best friend cats get hissy if one of the pair visits the veterinarian and smells funny.You can reduce arousal by limiting the sensory overload. Keep the kitten hidden behind a door in a separate room to remove the visual stimulus. Your adult cat still smells and hears the kitten when you confine the baby in one room. But confinement also tells your adult only PART of his territory has been invaded. Your adult still has access to his favorite beds, claw targets, and your lap. Clueless kittens don’t mind confinement if they have toys, food, litter box, and your attention from time to time. Shy kittens do better once they feel safe in their kitten room. That builds the baby’s confidence for the eventual nose-to-nose meeting.

Confine the kitten. Keep the solid door shut at least a week. During that time, monitor the adult cat's reactions. Sniffs, paw-pat games under the door, even hisses are normal. Associate positive experiences at the door by feeding treats or playing with favorite toys nearby. I like using fishing pole lure toys that engage kitten claws and redirect hijinks to legal targets.
Once hisses fade after a week or so, switch the door for a pet gate. The pet gate allows the cats to see each other and interact through the safety of the barrier. Continue offering treats and playing games with both cats. If either cat ignores the other, that’s fine. Don’t push them to interact. Cats move at their own pace. Aim for another week of interactions through the pet gate
When the kitten and adult either interact calmly through the barrier or ignore each other, simply open the pet gate. Supervise. If you have more than one adult cat, introduce the friendliest adult to the kitten first (separate the other in another room to meet later). Please don’t overwhelm the new kitten by presenting him with all the feline family at once. While the kitten meets Mr. Friendly Adult, let the other adult(s) spend time in the kitten room to get up close personal sniffs without baby distraction.
This first meeting may involve up close sniffing or them ignoring each other. Have treats or favorite toys handy to distract if necessary. Hisses are fine, as long as both cats keep their distance from each other. Growls mean you’ve gone too fast, though. Put the kitten back behind the pet gate for a few more days and try again later.

These steps outlining how to introduce new cats apply when visiting friends or family with cats. Introducing new cats takes weeks rather than days, though. Use these tips for a permanent adoption, or if you anticipate a weeks-long fostering situation. For shorter visits, keeping the kitten sequestered works best to keep adult resident cats (and the baby) stress-free and happy.

How to Introduce Adult Cats to Each Other

You can use many of the same kitten-to-adult introduction steps for introducing adult cats to each other. There are a few differences, though. It’s not unusual for adult cat introductions to last weeks longer, or even months. In some cases, the cats won’t ever become bosom buddies. But proper introductions increase the odds for tolerance, which can eventually grow into more in the years ahead.

Confine the new cat in a room with a solid door. A new adult cat poses a potential threat to the resident cat’s territorial claims. Two adult cats may attack each other at first sight. For that reason, sequestering the new cat prevents this knee-jerk reaction. Time allows the two adults to become used to each other’s scents and sounds before allowing visual triggers. Aim for at least a week, and possibly two weeks with the new cat sequestered.
As with kitten introductions, growls and hisses are normal. Watch for positive behaviors like paw-pats and silent sniffs under the door. Once both cats act calm, schedule meals so they eat favorite foods at the same time on each side of the door. Feed or play favorite games at the door with both cats (two people at the same time), to help each cat associate fun things with each other’s presence. After they’ve finished eating, swap out the meal dishes so each cat gets a whiff of the other alongside the yummy food smell.
Cats cheek-rub territory, marking it as both owned, familiar, and therefore safe. Friendly cats groom each other, sharing this comforting familial scent. Since the new adult hasn’t interacted with the resident cats, he or she still smells stranger danger scary. You can help the cats learn each other’s scents by swapping smells. Use a hand towel or clean socks to rub-rub-rub over the new cat, especially his cheeks, and drop the scented item somewhere in the rest of the house for the resident cat to find. You can do the same with the resident cat and share his scented sock in the new cat’s isolation room.
Watch both cats for clues they want to meet. Tail up, and ears forward with interest at the door indicates confidence. Crouching or hiding means the cat needs more time. Swap the closed door for the pet gate—draped first with a towel—and monitor the cats’ behavior. Continue feeding or playing within sight of each other. If the cats refuse to eat too close, move the bowls farther away. Let the cats decide on the pace. When both nose the towel aside for clear views, you can remove the shield. As with the kitten introductions, you can always take a step back and slow down the introductions if the cats tell you they need to slow down.
Adult cats will not want to meet each other until they feel comfortable and safe in their environment. Before a face-to-face meeting, swap out the cats. That allows the resident adult cat(s) to check out the isolation room, sniff the new cat’s bed and litter box, and get a better idea of just who this stranger is. Meanwhile, it allows the new adult cat to cheek rub the rest of the house, scope out cat trees, hiding spots, and figure out all the safe spots and escape routes. Only then will the new adult cat have interest in meeting a new feline friend.
Once you’re sure both cats feel calm and ready, open the pet gate, and allow the friendliest cats to meet. If you have more than one resident cat, conduct first meetings one by one. Supervise, and be ready to interrupt any growls or imminent attacks. Watch for airplane ears, one cat running away and hiding, and vocalizations. Cats play silently—so if it gets noisy, stop, and separate the cats.

cat smelling a second cat | How to Introduce a New Cat Into Your Home

Troubleshooting Cat Introduction Issues

Moving introductions along too quickly can lead to behavior problems between the cats. I get it. We’re anxious for our new kitty love to become part of the family. All too often, though, the resident cat might as well say, “I never agreed to this!” To learn how to introduce a new cat effectively, you must also learn the potential issues you may face.

Rough Play

Boy cats play rough. Kitten play aggression peaks at about fourteen-to-sixteen weeks. Normal cat play includes chasing each other, and wrestling. If they take turns, and both cats keep returning for more (and the play stays SILENT), don’t worry. Do watch because rough play can switch to aggression easily. But if chasing doesn’t stop, one cat always hides or tries to escape, and vocalizations increase, take a step back. The behaviors mean introductions went too fast.

Territorial Disputes

Adult cats argue over territory and who owns what. Reduce any potential kitty controversy by creating a house of plenty. Your home should have so many great toys, litter boxes, and scratch trees that cats have no need to argue. Lots of second-story territory along with cat tunnels allows cats to “own” their own real estate and hide if they want.

Scented Help

two cats cuddled up with one another | How to Introduce a New Cat Into Your Home

When disputes go on for weeks or months, speed up the acceptance by fooling the cats into thinking they already smell alike. Cats produce pheromones in their cheeks. These chemicals signal “friend” and “safe territory.” Use a hand towel to pet-pet-pet and rub-rub-rub the resident cat all over (especially his cheeks). Then use that same towel to rub all over the new kitty. This duplicates some of the family safe-scent cats share when they sleep together and groom each other.

Some commercial pheromone products mimic these signals. They can help with territorial issues, and others help reduce fear. I like the Comfort Zone/Feliway products (plugins, sprays, and collars) but there are others that may also work.

You can learn how to introduce a kitten or adult cat to your resident pets. The steps outlined above offer a basic roadmap. Just remember that many cats live into their late teens and beyond. Every cat introduction depends on the individual felines, so don’t worry if it happens faster or slower than you expect. A few weeks or a couple of months spent properly introducing your pets helps ensure a lifetime of love for you, and for your cats.

How about you? Have you introduced new cats to your existing furry crew? What tips worked best for you?

About the Author: Amy Shojai a certified animal behavior consultant, is the award-winning author of 35+ pet care titles and pet-centric thriller fiction. She lives in North Texas with her furry muses.

How to Introduce a New Cat Into Your Home