OH no! I bet your hen got attacked. Is the coon squashed, like hit by a car? You better be careful with this hen. She could have a nasty infection from that coon. There are antibiotics at the farm stores, but unless she's like your favorite hen in the flock or something, I'd cull her. It's...
holy moley-- Sounds like you have a rodent problem. I've never heard of a chicken chewing on another bird. They don't have teeth! Lice or mites won't do this kind of damage. You've got a mouse or something maybe that tried to chew off some feathers I bet. I suppose she could have done that...