Lots of breeders don't actually feed inferior products like Iams because they truly think it's good for their dogs, but because they get "breeder" discounts and incentives for referring new puppy owners to these diets:
https://breedsmartpartners.customere....aspx?MenuId=5
Good luck on your quest for a new (better!) breeder of Tibetan Terriers. And when you finally do get your puppy, raw is definitely the way to go. Maybe not as soon as they get home, but I personally would make the switch within the month. Growing puppies need the best food possible!