Hi, I have two female cats, one is about 3 years old and the other is about 2 to 2.5 years old. They are both indoor cats and have pretty much grown up together. They have always gotten along together just fine and play all the time, sleep together, and even clean each other from time to time.

Like all cats, they have their little fights here and there but it usually doesn't escalate into anything major. I also usually break it up by yelling and nothing comes of it. Well yesterday they started going at each other again so i broke it up, but for some reason they seem to be holding a grudge against each other this time around. The younger cat yesterday would just stare at the older cat and growl/hiss at her while the other did nothing. Thinking it was just a grudge between the two cats i went to bed thinking all would be fine in the morning.

This morning when i got up the younger cat was meowing and wanted attention so i gave her some. As i lay on the couch petting her, her older sister came around the corner and sat in the middle of the room on the floor. Of course now the younger cat who i was petting lost all concentration with me and jumped off the couch and walked up slowly to her older sister who then hissed at her before she hissed back.

It's been about a day and half of this hissing/growling between the two and I'm not sure what the problem is or how to rectify it. They seem fine with my wife and I, and will even let us pet them but for some reason they just don't like each other. Does anyone have any idea what could be going on with them and how to remedy the situation..? Could this be from a lack of smell from a cold or something, or did they just fight over something neither one of them wants to back down from..? Whatever it is, i just want them back to there fun loving ways as quickly as possible. Any help is greatly appreciated.

I heard somewhere that if a cat is threatened by another cat from outside, they can somehow transfer those feelings onto the cat they live with. Perhaps someone else knows more about this than me, but I wonder if one of them has had a fight with a neighbour cat, or is feeling a bit bullied?

Sometimes a cat can sense when another one is ill and take offence to that - is there possibly a chance one is poorly?

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both the above posts are good advice - if vet finds no problem ( urine infection etc) then maybe feliway or pet remedy plug ins would help a bit?

Thanks for the help everyone. Yesterday afternoon actually turned out a bit better between the two cats. Now the older one seems to have stopped hissing at her younger sister unless provoked, but this seems the opposite for her younger sister who still seems content on hissing at her from time to time, so I'm kind of leaning on maybe a kitty cold or something that is affecting her sense of smell. Cause we all know cats rely heavily on their sense of smell. Will check with a vet on Monday and see what they think. Thanks again for all the help.

Update: Just to let everyone know our two cats now seem to be getting along a little better. I was going to go ask the vet what was up with the hissing/growling today but they seem to be doing a lot better around each other so i didn't bother. Though things seem to be progressing, there still seems times where they hiss at each other, but at least the growling has stopped which puts me a little bit more at ease. Will keep an eye on it anyways.