I've never heard of this but I looked it up. Here's an article I found about it. It does list yorkies as one of the breeds this can occur in so maybe one of the breeders on here can give you some more info. The article does say it usually occurs in male dogs but the mom is still a carrier so parents of pups born w/ this shouldn't be bred any more and the pups themselves shouldn't be bred. Good luck. Guess you'll just be buying hats to keep their little heads warm. Can you post some pics? I bet their still cute, they're just unique and will need unique names. Kojak will be cute.
http://www.upei.ca/cidd/Diseases/der...otrichosis.htm