Oh my goodness that's terrible!
My best wishes go to your friend that she finds her dog. Her heart must be breaking right now.
You've probably already done this, but in case you haven't....make sure you alert not only vet offices, shelters and pounds, but also rescue organisations in your state (both all breed and GR rescue). You can find them through google. You could also alert the GR club in your state/area, they often have their own rescue attached to the club.
What ever you do, don't stop looking. Good luck! I hope you find her.
Cass.