I breed Yorkies,
and every litter I have I get one huge puppy.
Our vet said they are throw backs, from way back, before they bred them down to the smaller size.
The first time I saw one of them full grown I was shocked.
Luckily the lady didn't care and loved her Yorkie anyways. But I was still shocked,
as my female is about 11 lbs and my male is about 9 lbs.