I would certainly have test run to rule out any health issues, especially liver shunt, when he gets a bit older...make sure there isn't a medical reason that he is so small. Then again, smaller pups do happen in litters from time to time. It seems like there are lots of small dogs in his family tree, so that may be the case here. Of course, you don't want to end up producing especially small dogs, which is why it is important to know their lines well
before breeding and to never breed small dogs, especially females under 5 lbs.
