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Why is my senior cat suddenly hissing? Is it old age or illness?

Updated on September 23rd, 2025

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

Hi! I have 4 cats living with me right now. The oldest (Nurmal)(12-13) (We are unsure because we got her at the humane society. When she was like a year or 2 old.) Lately she hisses when one of the other cats walks by. Do you think she's doing this because of old age and she's getting cranky? This is new so we have been experiencing this for a month or 2 now. But I'm getting worried. Do you think something is wrong?

2 Answers

Most Helpful Answer

Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on October 22nd, 2017

I would have Nurmal (love her name!) checked out by a vet. Sudden changes in behavior in a senior cat can point to medical problems such as hyperthyroidism and arthritis (pain may make her cranky). I recommend getting a physical exam, geriatric blood panel, and urinalysis. These tests will help the vet identify if she is suffering from a medical illness. Should one be found, the vet can discuss treatment options with you. I would take her into the vet on Monday if possible. Good luck, I hope this helps!

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Mara Howard, DVM
Veterinarian
Published on November 24th, 2017
Thanks for using Petco Pet Education Center, formerly Petcoach! I’m sorry to hear Bailey is having behavior changes. When a cat gets older and has a sudden behavior change, we try to determine if there is an underlying medical cause for his changes, or if it is solely a behavioral change. Underlying medical issues (such as pain, diabetes, liver issues, kidney issues, etc) can present as behavioral change, and any of those would need to be ruled out so as to treat him appropriately. I would recommend Bailey be evaluated by his regular veterinarian to determine if there is any medical cause for his behavior (bloodwork, etc) and if not, what behavioral treatment options there are to help. Good luck!
1Pet Parents found this answer helpful

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