if you breed a dobe and a mastiff you have a mutt. but if you take the pups out of those littler that represent the traits you are trying to create a breed for and breed those, and then breed the best of those and so on until you have a standard. When there is a standard that you can expect when breeding, that is when you have a breed. But if you breed a Golden and a Poodle you cant guarantee a hypoallergenic dog, you cant predict what kind of coat it will have, etc. You need color, size, coat, temperament, etc standards before it is a breed.