I find this magazine to be one of the best when it comes to trying to make decisions for my dogs. I cannot recommend it enough. With no disrespect to vets I feel that it is my responsibility to read as much as I can for the health of my animals. It was my vet who told me that she only had like one or two classes about nutrition in vet school. Maybe this has changed but I do know that even in humans we have nutrition specialist which doctors will turn to.
http://www.whole-dog-journal.com/
Good Luck with your decision.