Coat Color in Pomeranians
We have not studied Pomeranian coat color using DNA because we have not been asked to do so. Therefore I must supply information
based on the alleles we expect to occur in this breed based on a review of many photos of these dogs and the standards in
some countries which specify coat color and our extensive study of the genetics of coat color in many other breeds (http://skyway.usask.ca/~schmutz/dogcolors.html).
Prior to 1996 the AKC standard read: red, orange, cream, sable, white, parti-color, black and black-and-tan. The main advantages
of specifying coat colors are:
provide educational information to owners and breeders
provide information to judges
provide information to geneticists who are then able to tailor a DNA test package which identifies the alleles for these
specific colors
identify which colors are excluded for either health, aesthetic or historical reasons
I would advocate this approach to most breeds. Pre-1996 the major genes and alleles causing variation in Pomeranian coat
color were likely:
A (agouti) = agouti signalling protein (ASIP)
ay fawn (cream to yellow to red with darker tips)
sable (some solid black hairs intermingled amongst reddish hairs)
at black-and-tan or brown-and-tan
E (extension) = melanocortin receptor 1 (MC1R)
EM melanistic mask
E eumelanin can be produced
e only phaeomelanin produced
K (from blacK......"dominant black") (gene identified but not published yet)
K solid black, brown or blue (eumelanin pigmentation only)
k expression of agouti alleles that express phaeomelanin possible
I (dilues only phaeomelanin) = ? gene (Co-Dominant)
I intense, not diluted
i co-dominant decrease in intensity
S (spotting) = ? gene (in pigs this is KIT but may not be just one gene in dogs)
S solid colored
si Irish spotting
sp piebald or random spotting
There are several coat colors that can be associated with health concerns. (http://skyway.usask.ca/~schmutz/conditions.html).
One such gene is MLPH or the D locus. Several, but not all dogs with a d/d genotype have Color Dilution Alopecia and/or
Black Hair Follicular Dysplasia. Although d/d dogs could be blue, grey, pale brown or a dilute red, it is unlikely that the
orange or cream of Pomeranians is due to this genotype since blue or grey are not listed as allowed colors and I have not
seen photos of such dogs. In addition, there are black-and-cream Pomeranians which have a decrease in phaeomelanin on their
undersides to cream but no decrease on their backs which remain black. It is therefore likely that it is the I gene that causes
the variation in shade in orange (e/e) dogs.
Another gene that causes major health concerns is AP3 which causes Grey Collie Syndrome. Luckily this has only been identified
in Collies since it is lethal to pups.
Yet another gene in the "blue" family that can cause health issues is merle. Merle can not be seen in dogs with an e/e
genotype. This e/e genotype occurs commonly in Pomeranians since orange, red and white probably account for the majority of
Poms. The problem is that M/M (homozygous merle) dogs are always deaf based on our studies. We recently genotyped 24 mostly
white Australian Shepherds and all tested M/M (based on the Clark et al. 2006 PNAS published test) and all were deaf. A proportion
of these dogs were also blind in one or both eyes since microphthalmia is another common side effect in M/M dogs. Although
in many breeds it is possible to educate breeders to never breed two merle dogs together this advice is not possible to follow
in Pomeranians since e/e dogs would not show the merle pattern. It would therefore be necessary instead to advise all persons
who breed a merle dog to use only a black or sable mate or to have DNA testing done on their red, orange or white mate prior
to breeding to be sure it did not carry merle.
Although albinism is rare in dogs, it does occur. The side effects associated with albinism have not been well documented
since the phenotype is so rare and may be caused by different genes in different breeds, each with different side effects.
This should not be confused with white dogs that have deeply pigmented nose leather and pads however which do not have health
concerns. The occasional white dog with pigmented leather is M/M but usually dogs of this genotype has splashes of mottled
color on their body.
Sheila Schmutz, Ph.D.
Professor, University of Saskatchewan
April 8, 2006
