welcome to the forum, and thank you for rescuing your girl!
I feed her Pro Plane with Lamb and she seems to be doing great on it, save the shedding.
If you search the food archives, you will see that anything made by Purina (including Pro Plan) is very cheap, low-quality dog food and is certainly the root cause of all this shedding (barring any medical disorders - you have had blood tests done to verify that all is well, right?). If you can buy a dog food in a grocery store or walmart, then is it not a good food. Iams, Purina, Science Diet, etc = don't do it
Please switch you girl over to a higher-quality food and add a capsule of Omega-3 fatty acids (ocean fish oil, 1000mg/day), and after a few weeks you should see a difference