What a lovely gsd! For her new food,I would recommend Solid Gold. Their Wolfking is for large breed dogs though my Sting loves their Barking At The Moon. Whatever food you decide on, I would do the switch slowly (mixing a little bit with the new and gradually increasing the amount of the new food and decreasing the old food) to avoid tummy upset.
Sting Chance von Gaard AKC GSD 2/8/2006