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Genetics of Parti Yorkie Coat Color
Parti Color Yorkies or the Biewer
Properly colored Blue and Gold Yorkies per the standard.
calling themselves Morkies, Yorktese, Yorkiepoo or
Yorkie mix or any other suchnames is that these
are just that - a mix breed.Just one more dog or
one more litter adding to the over population
problem and the problem with so many
dogs being euthanized each year.
The original history of the Yorkshire Terrier is included in Joan Gordon and Janet Bennet's "The Complete Yorkshire Terrier". Also included is an exerpt from Mr Ed Bootman of Halifax, England on the origin of the YorkshireTerrier printed in "The Stockkeeper in 1887". They state that the true origin of this breed is Swift's Old Crab, a Scotch Terrier, Kershaw's Kitty, a Skye, and an Old English Terrier bitch of the black and tan saddle. All this taking place back before 1850. Up until this time they were mostly known as Scotch Terriers, some as Paisley, Clydesdale or Skye Terriers. At his creation we know the original history and what went into creating the Yorkshire Terrier. By the 1860's these dogs were already being shown in England and entered in the stud book. Huddersfield Ben was born in 1865 and no Yorkshire Terrier can claim existance without him back in the pedigree.
Genetically the Yorkshire Terrier does NOT carry the piebald gene, which is what is needed for the large amounts of white coloring on any breed. The only way that gene could come into existance is for breedings to have occurred somewhere along the line with Maltese or Shih Tzu. My personal theory is that both are great possibilities.
The important issue we want to look at here is the SS which includes a description ot the Spotting gene. The information below is taken from Malcolm Willis' "Genetics of the Dog"
The genetic makeup for the Yorkshire Terrier is:
asasBBCCDDEEGGmmSStt
S Self colour to totally pigmented surface
si Irish spotting involving a few definite areas of white
sp Piebald spotting
sw Extreme-white piebald
Most breeds without white markings are SS but from time to time markings do appear and in general appear on toes, chest or muzzle. These marks can be present at birth and are lost during infancy. The ones that persist are not other s alleles but to minus modifiers at the S allele and will be limited to those minute amounts in those locations.
Irish spotting is also limited to certain areas of the body as the dominant S is, ruling out either gene in the makeup of Parti Yorkie Tri Colors or Biewers. Limited to forehead, chest, belly, feet and tail tip.
Piebald shows much larger amounts of white on the dogs then the Irish spotting gene.
Extreme-white piebald is seen in those breeds which are white in color. As a result of this double carrier of swsw all other colors can be suppressed.
(From Malcolm Willis "Genetics of the Dog")
So in essense, to have the white markings that are on the so called Parti Yorkie Tri Color or Biewer dogs, another breed had to have been in the mixture at some point. Since no one wants to admit this and in all honesty, it could be back far enough that no one is living any longer to admit to it, but unlikely that it is not much closer up. After some study of the current Biewer situation, which is somewhat the same situation, I've found they have both the Piebald gene and the Extreme-White Piebald gene. Some of the Biewer's are going almost solid white, which gives and indication of a couple different breeds.
Per Malcolm Willis' "Genetics of the Dog" When you read the genetic study of the Maltese, they have the Extreme-White Piebald gene.
Even though the genetic studies were not conducted on Shih Tzu, it is quite apparent that they are carrying the Piebald gene. Either or both could figure into the equation. The ones going white are heavy on the Extreme-White Piebald and the ones keeping color on the backs are of the Piebald inheritance. Either way, the mix wherever it happend, by accident or plan, this is NO longer a purebred Yorkshire Terrier.
In over 30 years of being involved in the sport and many Yorkshire Terrier champions, I have not had a Yorkshire Terrier with white. I find it interesting that the only ones coming up are the ones not bred by show exhibitors. A show exhibitor was getting them and had enough sense to realize there was more behind her breeding then just the Yorkshire Terrier and somebody had obviously done a breeding that was not pure Yorkshire Terrier. Otherwise the show exhibitors are not getting these white colored dogs.
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.
Cher Hildebrand
Goldenray Yorkies
Pictured here a Parti Yorkie Tri Color Biewer puppy.
If I personally had a Tri-Colored Yorkie, as a reputable breeder I would immediately spay/neuter the dog as the dog does not genetically represent a true Yorkie in breed type. Do not be misled by breeder's selling these dogs. They are not what a Yorkie should be and do not look like Yorkies, but more like a Shih Tzu and sometimes a Maltese. Beware!
Don't be misled that someday the Parti Yorkie will be shown with AKC. This is not happening. It's much like the white German Shepherd. AKC registers off colored dogs, including the Parti color Yorkie, but they can NOT be shown. AKC is only a registration body. YTCA holds the Yorkshire Terrier standard and will not allow the Parti Yorkie to be shown and that is not going to change. The Biewer's can NEVER be shown AKC as they are not registered with an organization acceptable in the US. So the papers with that organization can never be transferred to AKC. The Parti Yorkie and Biewer can NEVER become another breed with AKC either unless they acknowledge they are a combination of atleast 3 breeds. That information is right on AKC's website on Foundation Stock Service. When you work to create a new breed, it takes atleast 3 breeds to be involved in the makeup of that breed and of course they would have their own name.
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