Cat Friends Are Now Fighting

I have a co-worker and she told me she has two male cats. Both were fixed as kittens, and they are brothers.

She says they are now 8 years old and they’ve been friends their whole lives. She said about 6 months ago she heard some fierce hissing and she went into the other room and the two cats were fighting each other really bad. She said both were scratched and bleeding. She said she threw water on them to break them up.

Then she said after a day of seperation, they went back to being friends again. They will play and even sleep together and cuddle up.

She told me yesterday she again caught them in a nasty fight and had to break them up. Again she threw water on them.

Any idea why cats would suddenly start fighting? They were fixed and they are nice cats, they don’t spray or anything. Both cats were recently vaccinated in Sept so they had their check ups no problems there.

My co-worker told me they each have their own litter box and each have their own food and water. They always had seperate. The cats can go in and out of the house if they want, but they mostly stay in when it gets cold.

She also said by this morning the cats were all friends again.

Any ideas what’s up? The only thing I know cats fight over is a female. But they were fixed as kittens and they’ve never fought before.

The first comment makes this makes it a little less likely, but there is a possibility it is “redirected aggression.” Cats, even mild-mannered ones, are territorial beasties. Occasionally an intruder ( usually a cat, but sometimes other things ) appearing at a window can cause a high state of tension in some cats, causing them to lash out viciously at the first thing that crosses their path, including siblings. This can result in some pretty nasty fights and, rarely, permanent estrangement.

You can read up on the web about this - first one that came up on google for me: