We have 2 kittens that are sisters that we rescued together at 6 weeks old. They were best of friends and couldn't stand to be apart even for a few minutes. They are 6 months old and we took them in together to get spayed on Monday (5 days ago). When we picked them up Honey was hissing and being mean to Cinnamon. Contacted a lady at a local rescue and she said they were in pain from their spays and hormones were running wild so to crate them for their safety so they don't herniate their spay incision. So we took to big metal dog crates and crated them in the same room. We have been getting them out 1 at a time in a separate room to play. Last night we put them in a room together and played with them and Honey is still hissing and swatting occasionaly at Cinnamon. Poor Cinnamon is just walking around confused and doesn't understand why her sister hates her. From what i am reading it seems we are dealing with Unrecognized Cat Aggression. We have 2 other cats in the house and 3 dogs so we cannot keep these 2 apart for forever. Has anyone been through this and how long did it last? Also, any pointers on speeding up this process? I really don't think they would get in a huge fight and hurt each other, but poor Cinnamon looks terrified and I don't want her to be stressed out. Thanks in advance!