I don't think you have anything to worry about with Canidae - it should be perfectly appropriate for your puppy. It doesn't have a high protein content - 24%. Many foods, and actually most puppy foods, have higher protein content than that. Even many large/giant breed formulas have more protein than that. The *minimum* for puppies, incidentally, is 22%. Ideal is generally considered as 24-26% (as you'll note, Canidae is on the low end of "ideal").
As for high protein causing growth problems... the answer to that one is that nobody really knows whether it does or doesn't. This is a bit of a moot point, btw, since Canidae isn't a high protein food. But even so, it's worth knowing. There are some studies in existence that say that high protein ("high" is more like 30-40%) contributes to growth disorders and diseases. Others say it has no impact at all. Pretty much all agree on things like excess calcium and overall calories being dangerous, but protein is disputed. My personal feeling is that, eventually, the it-has-no-adverse-impact camp will be proven to be correct. But that's just my feeling and the current situation is that nobody knows for sure whether it's an issue or not an issue (and that includes your vet).
So, that's certainly worth knowing about and taking into consideration in your food choices. HOWEVER: it isn't very relevant to Canidae. This is not a 'high protein' food. It is average to low in protein, especially if compared against puppy formulas.
