I had a chicken that survived a massacre from either a fox attack or a dog attack and she laid in a dark corner for 3 days without moving, her head hanging down. I was afraid to disturb her. I thought she was merely in shock, but I had missed the real injury and only saw the superficial wounds but after 3 days she started moving around, I lifted a wing and she had a serious bite to her rib cage.
You should give Henrietta a dark place to be alone...give electrolytes or sugar water too.
The fact that she was bawling and in a panic flying into the car, means that she was grabbed by the dog or hurt herself in the escape, and probably is hurt internally or has injured her leg/hip, etc.
Chickens are amazing healers, just give her a hospital bed and care for her as you have been.