That's possible, considering the heat and the trauma, but she could just be hiding till she feels safe, too. If you didn't see any blood, a lot of feathers can be lost and there still be an intact chicken. My roo was attacked by the neighbor's dog, carried through two fields to their house, escaped and ran away, stayed gone all day, and came home on his own in the evening. He had a terribly bruised wing, lost a lot of feathers, but no broken bones, almost no blood loss. He is fine now, a month later. He is even growing back his tail feathers. I hope your girl comes home safely. Good luck!