Is This Normal? My Cat Hates Our New Cat

By: Chewy EditorialUpdated:

how to introduce cats

Is This Normal? My Cat Hates Our New Cat


My partner and I thought that our cat, Noodles, would appreciate having a little sibling in her life. WRONG. When we brought her new brother home for the first time, our sweet, cuddly Noodles turned into a wild cat, hissing and growling and threatening to attack the poor thing. Is this normal—or did we somehow botch Noodles’ introduction to her new buddy?


Here's the bad news: Noodles and her brother definitely got off on the wrong paw. But don’t despair! The good news is that Noodles’ reaction toward this unfamiliar cat is totally normal, and it’s entirely possible to salvage this budding relationship.

Cats can be highly territorial toward other cats, especially if they have not been socialized to other cats during their socialization period, which occurs between 2-7 weeks of age. But with a little knowledge about cat body language and behavior, as well as a hearty helping of patience, you can navigate this process.

So how do you introduce cats? Follow these steps to lay the foundation for a lifetime of feline friendship.

How to Introduce Cats: Steps for a Successful Transition

Sharing Scents

Give your new cat their own room with access to food, water, a litter box, scratch pad and toys. Keep the door closed so Noodles can’t enter. Your cats will be able to smell each other through the door, and they’ll pick up scents on you, too. Allow the cats to sniff your hands and clothing. If you see warning signs like dilating pupils, fur standing on end or vocalizing, you’ll need to distract them, such as by tossing a toy. Then, slowly get up and move away.

If either cat becomes agitated, you will need to take things even slower. Rub a towel or blanket all over one cat, then place it on the floor for the other to explore. Sprinkle favorite treats or catnip (if your cats like catnip) all over each towel and allow them to approach and sniff. These will help your cats form a positive association with each other’s scent. Repeat this towel game daily.

​Continue like this for 3-5 days, or longer if signs of aggression linger. Whatever you do, don’t rush this early phase! Every cat progresses at their own pace. But if you see absolutely no improvement after 3-5 days, seek help from a veterinary behaviorist or certified animal behaviorist.

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Trading Spaces

Next, rotate the cats into each other’s spaces. Keep them physically separate through a closed door, and watch them closely. You can let the cats explore for a few hours or even or an entire day.

Again, allow the two cats to sniff each other under the door, and monitor for signs that either cat is uncomfortable. Since there is a door between them, you will be listening for any unhappy vocalizations, such as growling and hissing.

If you don’t witness signs of upset for at least 24 hours, it’s time to initiate contact—but don’t open the door just yet. Use a string toy, such as a Pet Fit For Life 2 Feather Wand Cat Toy, to get Noodles to bat at it near the door. Use another string toy under the door to lure the new cat over. Allow the cats to bat at their respective strings, gradually bringing them closer together at the base of the door. Encourage the cats to play “patty cake” with each other’s paws beneath the door, if space allows. Look out for hissing, growling, yowling or hitting with force, all signs that one or both cats are agitated.

Face to Face

If the string toy experiment is a success, it’s time to let the cats see each other. Open the door an inch and allow the cats to peer through. You may hear a little hissing or growling when they first lay eyes on each other. Distract them from staring at each other by diverting their attention to a toy.

If the cats do not display signs of agitation, offer them treats, praises and petting. Try to get them both to bat at a string toy. As long as they remain calm, allow the cats to sniff and see each other for short sessions, about 5-10 minutes 3-5 times throughout the day.

However, if the initial growling and hissing continues or if one cat tries to strike the other, immediately separate the cats by closing the door. Keep them separate, continuing to offer each cat a scented towel from the other cat and practicing “patty cake,” for the next 1-2 days, then try opening the door a crack again.

When both cats can remain calm with the door open a crack for multiple 5-10 minute sessions, it’s time to move on to the next step.

Open the Door

Set up a pet gate in place of the door so the cats can see more of each other without any physical contact. Start with short periods of interaction, gradually lengthening the time of each session. While they are interacting through the gate, look for soft eye contact, blinking and elevated tails—all signs that they are feeling friendly.

If both cats display these signs, you can use two string toys, one for each cat, and allow them to play on either side of the gate. Continue to watch for relaxed body language. There should be no hissing, growling or any other overt signs of fear (ears pulled back, pupil dilation, crouched position) or aggression (fur standing on end, puffed tail, lashing tail, lunging forward to swat).

Let the cats interact through the gate for 1-2 days. If they remain calm, it’s time to move on to the next step.

Out of the Gate

That’s right: It’s finally time to meet face to face. Remove the pet gate, and supervise closely. Distract the cats with a noise if they begin staring intently toward each other.

Let the cats interact in person for 5-10 minute sessions, 3-5 times each day. If one of the cats appears overwhelmed or fearful, shorten their periods of interaction. If aggression rears its ugly head, separate the cats and revert to the previous step.

Even if all goes well during these brief sessions, keep the cats living in separate areas for a minimum of 5-7 days and supervise all interactions. Gradually extend the length of each session in 15 minute increments. If both are behaving well, you can periodically leave the room, remembering to listen for aggressive signals.

After 7-10 days without signs of fear or aggression, you can start leaving them home alone for short periods of time. You can use a pet camera to watch how the cats behave in your absence. If they appear to be getting along, gradually lengthen the amount of time the new brother cat can be alone with Noodles. Eventually, they’ll be safe together 24/7.

Remember: You don’t need to be a cat expert to introduce cats. But you do need to have plenty of patience and provide the cats all the space and time they need. If you take your time and move at your cats’ pace, there’s a good chance Noodles and her new brother will learn to love each other. Good luck!

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By: Dr. Wailani Sung, MS, PhD, DVM, DACVB



By: Chewy EditorialUpdated: