I was away for one night--chickens secure in their animal proof enclosure. I came home to find one of my 3 yr olds, dead, with her guts protruding out---a bit too squeamish to look closely, could have been coming out her vent, or her side. She looked a bit funky 2 days ago,sitting down--sluggish. No sign of any predators, feathers, etc. just a very bloody mess on her side. Does anyone know what might have happened?