I'm not sure a vets office will even know what that food is. Mine never heard of it before. Try a local pet store. There is a store finder on their website.
Actually, Natura is in a LOT of vet offices now. They're the high-grade Science Diet as far as vet endorsement is concerned.
There is a vet student on couple of other boards I post on, and she said that Natura has contracts with vets now just like Science Diet.
Maybe vets will start getting a clue on nutrition now.