I am not here to scold you, but I did want to share two stories with you. Many years ago, I had a Rotty and she came into heat. We had her in a kennel, on a cement slab, inside a fenced in back yard. There were no other dogs in the neighborhood. She still became pregnant. My best friend's mother had a chihuahua in heat and let her out to go potty. After 15 minutes or so, her dog had not come back. She went to look for her and found her tied with a male german shepherd. Because he was so large, her whole back end was left paralyzed. Hormones will make a dog go crazy and they will run for miles, dig through wood, chain link, and concrete, and find every means possible to get what it is they want.
Please have your girl checked and please be more careful with her in the future.
YorkieProud