Welcome to YT!! You are going to be such a good yorkie mom, and such a smart person for wanting to understand the breed before actually owning one.
Ok, tip time. To find a good breeder, I recommend you check out the YTCA, the yorkie mother club. They have a breeder referral page, (breeder contact) where they have YTCA members that breed listed from all over the US. All good breeders will have answers to all your health questions.
Also, really good reading material that all soon to be yorkie moms and dads really should read.
http://www.yorkietalk.com/forums/yor...ead-first.html http://www.yorkietalk.com/forums/yor...ease-read.html http://www.yorkietalk.com/forums/yor...ead-first.html http://www.yorkietalk.com/forums/yor...uch-thing.html