When Shadow was alive Mini would always fight with her. Female/female fights ARE the worst. And every fight had some sort of injury (usually on poor Shadow!)

Then we've had male/male fights with Micki and Jack, but they're never serious and if we clap our hands or yell "Hey!" they stop.

Come to think of it, I've never had a male/female fight at the house and right now we have 2 females and 2 males.