This is actually not out of the ordinary at all. These tiny yorkies have been INTENTIONALLY been bred down to nothing for no good reason and often to the detriment of their health. However they still carry the genes of being 10-15 pound dogs and it occasionally pops up randomly in litters when the right two dogs are put together. Then of course there is the cases where it's probably due to the continuation of the production of the growth hormone that stops/slows down in smaller dogs which keeps them smaller. |