Retrievers were bred primarily to retrieve birds or other prey and return them to the hunter without damage. Although spaniels and some pointing breeds routinely retrieve game, and many retrievers are skilled in finding game, retrievers are distinguished in that non-slip retrieval is their primary function.
As a result, retriever breeds are bred for soft mouths and a great willingness to please, learn, and obey. A soft mouth refers to the willingness of the dog to carry game in its mouth without biting into it. Hard mouth is a serious fault in a hunting dog and is one that is very difficult to correct. A hard-mouthed dog renders game unpresentable or at worst inedible.