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Why is my older cat suddenly mean and attacking the younger one?

Updated On September 23rd, 2025

Pet's info: Cat | Mixed Breed | Female | spayed | 13 lbs

We have three cats in a 2 bedroom apartment. We have had the 2 of the cats for 3 years and the other one for 2 years. One of the older cats, who has always been docile and nice has recently turned very mean to our younger cat. She has not let her out of our bedroom and stalked the door hissing and attacking her every time she comes out. This is very recent and started about 2 months ago. Before then they all got along so well. What should we do?

2 Answers

Most Helpful Answer

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Answered By Jessica Desrosiers

Veterinary Technician

Published on August 20th, 2019

A sudden behavioral change in cats that previously got along with no other changes to the environment can sometimes indicate issues such as underlying pain or illness. Bringing the cats in for an exam is a good first step to rule out any health issues that could be causing the aggression. If they check out healthy, adding in some pheromone diffusers can help with inter-cat stress. Making sure each cat has their own access to food, water, litter, places to hide, etc can also help decrease tensions.

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Other Answers

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    Answered By Dr Stafford, BVetMed, MRCVS

    Veterinarian

    Published on July 14th, 2017

    If they used to get on but now fight, this would suggest something has effected Peanutbutter. I would take it to the vet tonbe examined in case there is a source of illness making it irritable or sore. Failing that yiu have taken many steps to reduce stress, you could also buy a feliway pheromone diffuser.

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