I have a ten year old spayed female, and a 14 month old siamese female who I had spayed 3 months ago. They have been friends for the most part, playing and sleeping together. A few days ago they got into a huge, screaming, urine spraying fight. This has happened a couple of times since. They are mostly avoiding each other. The older cat is very fearful (normal for her), and the younger is very aggressive (just since the fight). She also tried to kill my ferrets who she previously enjoyed playing with. I've had the ferrets for four months. Any advice on how to heal the rift?