premium dog foods

Question
My 18 month old german shepherd has been on royal canin (as recommended by the breeder) and has done very well. I also supplement this with a few ounces of raw turkey or chicken every day. I have recently alternated with blue buffalo whose protein content is 42% as compared to 26% for royal canin. Both are expensive. Is it worth it and is this too much protein?  Her stools are fine with both.  Thank you.

Answer
I have never seen any evidence that premium foods are any better for dogs.  When I have asked for proof of it on other sites, many times the answer I get suggests a lack of critical thinking skills.  Those advocating them lose credibility with me when I catch them in clever half truths and distortions.  If they had a strong case, they shouldn't need to be deceptive.  I am afraid much of what you find on the net is posted by small, part time reps that distribute the premium brands.  

I do know the service dog schools have looked at different diets and settled on common brands.  Even their breeding stock eats Pro Plan, Iams, and such.  They have far more data to base decisions on than anybody, maybe even the large manufacturers.  

The excess protein in the higher formulations is burned off as energy.  that does put somewhat of a greater burden on the kidneys, but shouldn't hurt a healthy dog.