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Why are my brother cats suddenly hissing, growling, and fighting?

Updated On September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Male | neutered | 3 years old | 8 lbs

I have two brother cats, since they were 2 mos old. They are 3 years old now. Just this morning, first time ever. They started hissing, growling and puffing up at each other. I examined each one and neither seems to be having any kind of pain or obvious medical condition. What the heck is going on? They always play, eat and sleep together and now we're at war!

1 Answer

Most Helpful Answer

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Answered By Dr. Elizabeth

Veterinarian

Published on August 1st, 2019

If only pets could talk! Cats can be very reactive and can also get frustrated easily. It’s possible they saw another cat out the window and are reacting. You may try to separate them for a few hours. Keep the environment calm and check on them frequently to make sure they are not agitated. You want want to close the blinds to block out any views of the other cat. If the behavior continues, have them examined by the veterinarian. I hope this helps and please feel free to post any additional questions.

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