I have a DK and feed Proplan but any quality food will work. I feed my dog this is because the breeder feed the dog this. The thing about high qualityfood is the consistency of ingredence. The cheap foods change percents of ingredences depending on price so if beef product is expensive they will increase percent of something cheaper but keep it within the certain precentage range. The high end dog foods keep a consistant percentage for each ingredence so if the cost goes up the quality stays the same. This is important because you know you pooch isn't getting alot of fillers. It also helps if your dog has stomach issues.

Good luck with you GSP