Im no breeder,but I certainly beleive that a puppys size can fool you
I was sent pictures of the litter (of 3) that I got Milo & Bella from the day after they were born,and they were all the same size.After that,I was sent pictures every 3 days until I could start visiting them myself (and choose my puppy) at just over 2 weeks old.They all seemed very similar in size until we skipped a weekend visit.Bella and Milo were still the same but their sibbling was now HUGE!! lol.
The day we bought Milo & Bella home (at 6 weeks old) they both weighed 1.7lbs,yet their sibbling weighed 2.7lbs! I have no idea how she grew that much so quickly (it happened in like 2 weeks!),but there was deffinately no switcheroo because there was no other litter and you could clearly see she was the same puppy (one of her back feet was white).Just genetics I suppose
