cat is suddenly aggressive

by Kristen
(Quincy, MA)

My 3 year old female cat has all of a sudden starting to become very aggressive. She was first agressive

to my 10year old male cat who was in the household before we had got her as a kitten. They were very friendly until
about a couple of weeks ago. In the mean time we have gotten a hamster. She is now hissing and growling
at me, my sister (who lives with me), and our fish! Last night she urinated on the floor and when my sister
bent down to console her after she had the accident she attacked her and hid under the couch. She is now afraid of everyone
in the household. I am really concerned about her. Could she have a UTI or be bothered by the hamster?
What should I do?

Sometimes cats can react strangely to changes in the home. Smells, new furniture, new people, different routines etc can all frighten a cat and sometimes they react aggressively because of this.

If this is the case then your cat needs some time out for a few days in a confined space such as a small room, with her toys, bed water, litter etc. This will give her time to calm down and relax. you may then want to consider reintroducing your other cat and perhaps even the hamster to the room ( in cages of course) to help her to get used to them in a controlled environment.

This behavior is known as aggression truama and I have more information about this behavior here


If after this time she is still acting aggressively for no apparent reason then having her checked over by a vet may be a good idea to rule out any other possible causes.

Hope she is back to her old self soon


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