Strange behavior..help

I have two female cats who are sisters, named Rosie and Spunky. They've always been very loving towards each other, and Spunky has always been really protective over her sister. Well, Rosie recently had kittens with a stray cat, and now when her and Spunky see each other they hiss and swat at each other's faces. Spunky attacked Rosie once, and I had to seperate the two of them. What's going on?

I would suspect something due to the pregnancy.

Do you plan on getting your two girls spayed?


Spotz

It could be that during the pregnancy Rosie's scent changed and now Spunky doesn't recognize her sister. Plus Rosie has all the kitten's scent on her as well making her a double threat and she is protective of herself for probably the first time because the kittens depend on her.

You can take vanilla extract and put it on both cats under their chins, between their shoulder blades and at the base of their tails about 3 times a day for about 4 days. You can also start running a Comfort Zone Room diffuser by Farum Pet to help ease the stress in the house.

Good luck!