I think checking with your vet might be a formost thought -however make sure he doesn't shove Science Diet down your throat just to make a profit off of it.
I could sit here & list pros vs cons all day, but here is my simple, latest example. My 19 mnth old great dane show girl Sadie - if I feed her Purina Dog Chow ~$23 bag (40 lb) will eat 12 cups a day. If I feed her Purina Pro Plan Performance ~$40 bag (37.5 lbs) will eat 5 cups a day.
The initial investment seems harder to swallow but when you break it down I am really saving money big time, plus of course there is less poop, and the ingredients are better and more filling and my dog looks great - she has to, she's a show dog.
I'm not saying go buy the same food exactly (especially not for that young of a dog) just an example of a how it can break down for you that better for that may *seem* more expensive actually breaks down to being better for everyone.
HTH!
Kristi