Some say, ......." Genetically the Pomeranian does NOT carry the white 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. ???????
The important issue is the SS which is a a description ot the white gene.
The information below is taken from Malcolm Willis' "Genetics of the Dog" The genetic makeup for the YT 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.
white spotting is also limited to certain areas of the body as the dominant S is, ruling out either gene in the makeup of the Parti, 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 Party, 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.