I have two female cats from the same litter, we lived in a flat just the three of us for the first year of their lives, now we're in a house with garden access, my DP and two other people. They're 2.
They used to get on great - cuddling, grooming etc. Then randomly 6 months ago of them started hissing at the other every time she passes her and occasionally swipes.
I'm guessing it's maybe a territory thing now that they have a lot more room, or the now lively household making her anxious?
Does anyone have any tips on dealing with this please?