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My cat is still aggressive with new kittens after months. What to do?

Updated on September 23rd, 2025

Pet's info: Cat | Mixed Breed | Female | 6 lbs

Alyssa has always been very affectionate with humans. When we got a puppy she would hiss and growl at him but eventually she got okay with him and now he can sit there licking her and she doesn’t care. But anytime she’s around the two kittens she will sit there and growl. It’s been four months. It didn’t take this long with the puppy. She has lunges at the female kitten twice but never at the male. I’ve tried doing the through the door thing but she just growls and refuses to go near it

4 Answers

Most Helpful Answer

Makenzie Kurth, DVM

Answered By Makenzie Kurth, DVM

Veterinarian

Published on June 28th, 2018

Thanks for using PetCaoch! It’s not uncommon to hear about behavior like Alyssa. It can take a lot of time and patience for them to get along but here are some tips for decreasing stress for Alyssa in the short term.

-Feliway- calming cat pheromone- comes in many forms from pet stores or online. 



- Adding a litter box. Studies show that the ideal number of litter boxes for a home is #of cats +1 . This is regardless of how clean you keep his current litter box.



- making sure she has plenty of “high space”. The safest (and therefore least anxiety-inducing) place for a cat is up. If you don’t already, get a cat tree or put up a shelf or two that she can go perch on. 



Feeding them in separate rooms with two or three water bowls throughout the home is also a good idea as perceived competition for resources is a common problem in cats.


Best of luck to you and your kitties!
Vote Icon1Pet Parents found this answer helpful

Related Answers from Veterinarians

  • Answered By Makenzie Kurth, DVM

    Veterinarian

    Published on June 8th, 2018

    Thanks for using Petco Pet Education Center, formerly Petcoach. This is not an uncommon story so don’t feel bad! Usually this stems from underlying anxiety- probably starting with getting the new kitten.

    Below are some tips that have been shown to reduce stress for cats and may help settle things down at your home. If these are not helping after a month or so, consider talking to your vet about anti-anxiety medication which can make a world of difference.

    -Feliway- calming cat pheromone- comes in many forms from pet stores or online.

    - Adding a litter box. Studies show that the ideal number of litter boxes for a home is #of cats +1 . This is regardless of how clean you keep his current litter box.

    - making sure she has plenty of “high space”. The safest (and therefore least anxiety-inducing) place for a cat is up. If you don’t have one (or two) already, get a cat tree or put up a shelf or two that she can go perch on.


    Best of luck to you and the kitties!

    Vote Icon

    1Pet Parents found this answer helpful

  • Answered By Makenzie Kurth, DVM

    Veterinarian

    Published on April 3rd, 2019

    I’m so sorry to hear about Tommy! My best guess is that he is very stressed about the move and the new cats he now has to get used to. There are several things you can do to help him feel less stressed.

    -Feliway- calming cat pheromone- comes in many forms from pet stores or online. 



    - Adding a litter box. Studies show that the ideal number of litter boxes for a home is #of cats +1 . This is regardless of how clean you keep his current litter box.

    

- making sure he has plenty of “high space”. The safest (and therefore least anxiety-inducing) place for a cat is up. If you don’t already, get a cat tree or put up a shelf or two that he can go perch on.

    Keeping him away from theotber cats for a few days to make sure he has no competition for food or litter boxes can also help.

    If no improvement in a week, or if worsening in any way, see your vet. Maybe there is a medical reason for his lethargy (pain, disease, etc)

    Best wishes to you and Tommy.

    Vote Icon

    1Pet Parents found this answer helpful

  • Answered By Makenzie Kurth, DVM

    Veterinarian

    Published on August 25th, 2018

    Thanks for using Petco Pet Education Center, formerly Petcoach! Congratulations on the newest family member. Time and the ability to be alone will be most important but here are some other suggestions for reducing stress in cats.

    -Feliway- calming cat pheromone- comes in many forms from pet stores or online.

    

- Adding a litter box. Studies show that the ideal number of litter boxes for a home is #of cats +1 . This is regardless of how clean you keep his current litter box.



    - making sure he has plenty of “high space”. The safest (and therefore least anxiety-inducing) place for a cat is up. If you don’t already, get a cat tree or put up a shelf or two that he can go perch on.

    Best wishes to you and Mousewhisker!

    Vote Icon

    1Pet Parents found this answer helpful

Smart Picks for Smart Questions

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How to stop my cats from hissing and chasing the new cat?
Unfortunately it's going to take time. That said, there are a few things you can make sure of to help reduce stress, especially in a four-cat household (which is a lot!). Making sure each cat has their own space where they can eat, drink, play, observe, etc without the other cats bothering them can help reduce territorial disputes over these items. Pheromone collars and plug-ins (Feliway) can also be placed on stressed out individuals, or in shared rooms (since everyone seems to be stressed) to help reduce inter-cat aggression. Making sure to have at least one litter box per cat will also help reduce stress and competition over them, and reduce the chances of accidents elsewhere. Otherwise, continued slow introduction of the cats is best. If anyone starts to get agitated or too excited, removing them to let everyone calm down and settle back in is best. Continued aggression and upset may also need a trainer or veterinary behaviorist's help. That said, if your home is very small, four cats may just be too much for everyone to get comfortable.
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My cat is aggressive after sister had kittens. Can I save their bond?
Changes in the social structure in a household like this can be very stressful for cats. They are not a very social species by nature, and it's often very hard for them to accept "newcomers" - even if these are her sister's kittens. I would recommend making sure that the aggressive cat has her own area where she can get away completely from the kittens and your other cat whenever she wants to - this should be a comfortable room with a litter box, food and water bowls, a cat tree or other resting spot, etc. This way, she can be on her own if she prefers to, but can still come out an interact with the other cat and her kittens if she chooses. Feliway diffusers in the areas where she spends most of her time may also help to reduce her stress. It may take her weeks, months, or even longer to adjust, so be patient - some cats never really adjust, unfortunately, and may need to be kept in separate areas of the house to keep everyone happy.
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My cat is aggressive after spay. How do I reintroduce them?
This may be difficult to correct but it generally can be done. Continue using the diffuser. Try switching litter boxes, beds, and rubbing each cat with the same towel to try to get them to smell like each other. Here are some links which may be helpful: https://www.petcoach.co/article/7-ways-to-calm-an-anxious-cat/ https://www.petcoach.co/article/bringing-home-a-new-cat-or-kitten/ Here is a great article about cat's instinctual needs: https://www.petcoach.co/article/why-every-cat-needs-a-place-to-climb/ Setting aside 30 minutes a day for vigorous play for both cats or switching the food to Royal Canin Calm may help. The veterinarian can also prescribe medications which can help with aggression. I hope this helps and please feel free to post any additional questions.
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How to introduce an aggressive new cat to a shy older cat?
Hi there and thanks for using Petco Pet Education Center, formerly Petcoach! Congratulations on your new kitty! In these situations it is best to do introductions very slowly. Some suggestions I have for you are as follows: 1) Use a Feliway diffuser to reduce overall tension in household 2) Go back to the beginning and over the first week introduce by smell only (introducing cats to each others bedding or something that has their scent on it) 3) Then introduce by sight only but no direct interaction. Do this for a week 4) Finally introduce cats together but only with direct supervision and with plenty of escape routes for both cats. Only leave them together for a very short time at first 5) Have plenty of tall cat towers and other things for the cats so they can observe each other from a distance 6) Have at least 3 litter boxes in different locations and definitely continue to feed separately and have separate water bowls. I hope this is helpful! Good luck to you and Malish!
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My older cats won't accept the new cat. How can I stop the fighting?
The next step is to rotate rooms daily for at least 2-3 days. This allows the new cat explore the rest of the house while the resident cat spends some time in the new cat's room. This will give your resident cats a chance to smell the new cat and rub their own scent on objects. The cats should be fed in each area with wet food twice daily, and it is also good to play with the cats in each area at least twice daily. The practice of setting up a schedule of feeding treats of wet food, as well as a playtime routine, minimizes anxiety and makes the cats feel more secure. Keep the cats in separate areas for as long as it takes to allow them the chance to become desensitized to the smells and sounds of the cats in the other area. When they all seem particularly relaxed with this process, begin to expose them to the sight of each other. A good way to accomplish this visual introduction is to bring the new cat(s) in a carrier to meet your cats and sniff each other through the carrier wire door. Place the carrier on the floor and allow them to meet this way several times a day for about an hour. Continue these meetings for several days or until they remain calm in each other's presence. If and when the cats are able to stay calm in each other's presence during these meetings, it is time to let the new cat out into the rest of the house for a few minutes. The length of the visits can be increased gradually each day. Depending on the personalities of the cats involved, this process may take a few days or a few months. If it appears that any fighting maybe be close to occurring while you are supervising, put the newcomer back in his/her room and proceed more slowly. If those supervised play times go well, you can begin to allow them to cohabitate in your home. If any aggressive behavior occurs at any time, begin the introduction process again. It is very important to understand that this process can take as little as a few days, to sometimes much longer. It is all dependent on the cats involved. If things don’t go well right away... One of the most important steps to dealing aggressive behavior between cats is to recognize the different types of aggression and understand their underlying causes. A short list and description of some commonly seen aggressive behaviors include: chasing; ambushing; hissing; swatting; and/or biting. If you see these behaviors, seek help from your veterinarian. Most cats get along fine if the introductory process is done correctly. Please seek help from your veterinarian if you feel that things are not progressing well, or if you have other questions.
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My cat hisses and attacks new cats. How do I introduce them safely?
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Why is my cat isolated and not eating after a new kitten arrived?
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