Can a large puppy get an extremely small dog pregnant?

I have a very, very small female Yorkie who has not been fixed. The vet told me not to worry about it since she is never left alone with other dogs, and there would be more risk doing the surgery due to her size (2.6 lbs). I am thinking about getting a Great Pyreneese puppy (male) and would obviously get him fixed when he's old enough. My question is, can a large male Great Pyreneese puppy get a 2.6 lb Yorkie pregnant? How would I go about getting a large breed male puppy without putting my Yorkie in danger? She loves large dogs, and they love her...I just don't want their "love" to go past licking until I can get the big guy fixed. =]

Male dogs cannot impregnate females until they are six months old or so. If the puppy is young, then he cannot breed with your female. Bigger breeds like pyrs take longer to mature than small breeds, so he might not be physically able to impregnate a female until he is 7-8mo old.