Yes, Yes, Yes! PUT HER ON A LEASH!!!!
I lost my little male yorkie this way in January and trust me, this is not something you want to happen to your baby girl
It's heartbreaking. I'm still not over it and I don't think I ever will be. Seeing him laying there in the road like that is a site I can't get out of my brain.
It was completely my fault...you don't want to live with that kind of guilt.
Just last night, our 7 month old female yorkie was on the deck with my husband and myself. We were sitting so that we *thought* she was protected from running off the deck...WRONG!
She ran!!!! Down the steps and into the front yard straight for the road. I ran and yelled and hubby did too. When we finally caught her, I was crying and hubby was shaking all over. All we could do was hug each other and her.
This after we knew we should never let her out with being on a leash. I promise it is the last time ever! I always carry her to the backyard and put her in the fenced in area when I'm outside working. For some unknown reason, hubby wanted her on the deck with us. It was so scary, neither one of us could think straight after that.
So PLEASE for your sake and the sake of your fur baby, never let her off her leash. Use a harness to protect her throat. (in other words, don't attach her leash to a collar)
You can also use those cork screw stakes to put in your yard with long nylon leashes and that way she can play while you do yard work.
Terriers will bolt, no matter how well they are trained. If they see a bird, a rabbit, a person, whatever...they will run!
All the best.