I have a neighbor who has two cats. One is 2 and the other is 5 years. They are indoor cats. They got together wonderfully until a little while ago... her one cat was looking out the window and started freaking out. There is a neighborhood cat that is around that she might have seen out of the window. Dorothy the owner said her kitty Callie shrieked at whatever was there then Callie attacked Babe. But that night slept together on the bed. The next day when they were by the door they started fighting. Callie sits at the door and just wants to get her now. The thing is they have gotten along their whole life then all of a sudden they started fighting. Ever since she has been beating up and hissing at the other kitty and have had to be separated. They were best friends. I don't know what she seen out the window had to do with it but their owner is sad and crying. Her husband just passed away and all she has left is her cats. She doesn't know what to do and i'm trying to help all I can. I need all the suggestions I can get.