My 61/2 pound female had a singleton puppy her first "litter". When we had the xray done, the vet came in and told me we had ONE LARGE PUPPY!!!
Totally freaked me out for the next week or so before the whelp. The puppy weighed a whopping 6 3/4 ounces, but thankfully my girl got him out without needing a c-section. The "big" little boy grew up to be just in the 5lb range though........he is a little over 1 year old now.