My Great Dane is 13 and has been fed Pedigree her whole life so is expensive food really necessary?

I feed my dog pedigree also. As far as dog food brands go it's no "dads" or "Old Roy". It's in the middle range. Not every dog owner can afford to feel their pet science diet, it's the way things are. However Pedigree gives your dog adequate nutrition for their needs (providing you purchase the right form for your size dog). Anyone who says differently is selling their label to promote commercial gain.