I just thought this might be of help to any one who is puzzled about mixed breeds, pure breeds, etc... I'll shoot first:
If the sire of the puppy were an "X" breed, and the dam were a product between "X" and "Y" breed; would it be correct to say that the breed of the said puppy is an "X" breed, and not an "XY" breed? Or would you rather consider it mixed breed?