Please help! My 4 year old cat (Thelma) has been having episodes of aggression (attacks that have drawn blood) towards her sister (Louise) and me. I got them together as kittens, they used to get along very well, groom each other, etc. But that changed around 2 years ago. It started out not very often, maybe 6 months apart. It seems to happen when Thelma thinks Louise is being hurt, or when Thelma is startled (and Louise & I are close to her). It has become more frequent (once a month) & each time it takes her longer to "get over it". Thelma has been to the vet, and has started to take Buspar. She had an episode after being on the medicine for a month. The day after the episode, Louise had to go to the vet for ear cleaning & dental, Thelma hissed at me when Louise was not there, and since Louise has come home, Thelma won't get close to her, and if she does, she hisses and growls. This has been going on for a few days now. It has never lasted this long before. Tried one dose of Valium, didn't work. The Buspar dose has been increased. They both have their claws. Thelma's a couple pounds heavier than Louise. Louise does defend herself, but she doesn't trust Thelma. Would appreciate any input. Sorry for the lengthy post, but this doesn't even cover it all. Thanks!