Growth

Question
How does puppy chow affect the growth of my GS dog?  Is that not a biological/genetic determination?  My dog is 4 1/2 months old and weighs 58 pounds. You cannot see his ribs, but you can feel them.  When viewed from the top, his "waist" dips in on both sides.  I believe he is well porportioned and so does the vet, but he did mention switching him to adult dog food.  Why?

Answer
Genetics determine dog's adult size.  How rich of a diet determines how soon it reaches that size.  The early switch to adult chow slows growth, giving more time to develop sturdy joints and good hips.  Over weight is another big problem, but many Shepherds refuse to eat enough to be overweight.  If you go to http://www.longliveyourdog.com/twoplus/RateYourDog.aspx likely your dog will be close to the ideal body condition.  So be happy your vet is on top of things and giving you good advice.  The word is slowly spreading.  I first learned of it in 1992 when we were raising our first puppy for a dog guide school.  You will be in good company.  I know many service dog schools make the early switch.