I took Tyson in for his first checkup with my vet and he suggested getting him on a large breed puppy food. His reasoning is the same from what i've heard. The larger breeds can grow too fast for their bones and could cause hip dysplasia *sp?* and other skeletal disorders later in life. He said, you want his bones to grow stronger before the rest of him does which makes sense. The only kind of large breed puppy i've seen around here is Royal Canin which is a good quality food.