I purchased two blue and gold Yorkie's. They are AKC regestered. As far as i know, there's no extra health concerns for my puppies. They were bread from two blue and gold Yorkie's. I have no clue how to research the health issues but i believe it's like the red haired humans. Its a rare genetic color they carry. My puppies don't show much blue atm, but they will they get older. There hairs are starting to change a little but they are only 17 weeks old. I can't post pictures as I'm not computer savvy but if you email me pictures I can email pictures of mine. They are silvery, gold, brown, and black haired, but I'll send a picture of dad for you to also look at.
Kietian22@yahoo.com