Linda Bush ( a Yorkie show exhibitor of many champions)
"was able to provide invaluable information on the show exhibitor and pedigrees which concludes who the culprit dog was in the past that started the Parti Yorkie Tri Color Biewer in the US.
This is a wonderful breed, but breeds are controlled by standards and that is the way it should be. To be protected by breedings that can harm the breed. It has been posted publicly that there are inherent problems in these white colored dogs and a lot are not living past 7 or 8 years of age. This is also not a problem with Yorkshire Terriers. That genetic disorder has been brought into the breed they have created, with whatever other breed/breeds they have in their background. In doing research I have found that numerous breeds with white do have associated health issues.
It also is noted by some on websites of these breeders of parti's that you can NOT get parti's from 2 regular Yorkshire Terriers. Well then how did they get them in the 1st place? Supposedly they got them from 2 Yorkies. Yet this proves a contradiction itself. They acknowledge all Parti Yorkies go back to a certain English dog. The one show exhibitor in the US that also was getting parti color Yorkies had breeding from the same kennel in England.
At this point I think the most important issue to look at is the fact that the Yorkshire Terrier only carries the SS gene, not the piebald gene which is needed for the white coloring. "
Top Parti Yorkies Genetics Party Color and Biewer
"Disqualifications:
Any solid color or combination of colors other than blue and tan as described above. Any white markings other than a small white spot on the forechest that does not exceed 1 inch at its longest dimension.
Approved July 10, 2007
Effective October 1, 2007"
American Kennel Club - Yorkshire Terrier