I have a seatbelt cutter clipped to my sunvisor. I wish this poor girl and her Golden Retriever had one too.
As a former EMT and ambulance worker I will tell you she was most likely unconscious, the dog most likely perished from the impact. She may have also perished as a rear impact of that velocity more than likely severed her cervical spine. Air bags have no effect in a rear collision of that nature. Her body accelerated and her head did not. He and his girl survived because of front crush zones and air bags.