by Fred Lanting
 

The white German Shepherd Dog is not “recognized” by most national kennel clubs around the world, because most are affiliated with or influenced by the true “parent club”, the SV, in Germany. Even in those countries in which the major national “kennel club” has maintained more independence from FCI, SV, etc. (such as the USA, the UK, Australia, and a very few others), they generally follow the German (SV) breed standard guidelines to some extent. These consider white coats to be a show (or even a registration) disqualification.
 

However, there are large populations of white GSDs in a great number of countries, most notably the USA, but also good numbers in the UK and the rest of Europe, and fewer in other countries (though still more numerous than many breeds). Some have established the white dog as a separate breed, regardless of the same heritage. In all of these communities, the genetics of coat pigment regarding this color variety are mostly misunderstood. For a fuller treatment of coat color genetics with regard to the white dog, see my book, The Total German Shepherd Dog (Hoflin Publ.). But here, I will give a smaller treatment of one or two questions that have come up in groups of fanciers who do not have any compunction against using white dogs in their gene pool. One such group consists of people who fancy the GSD variation known as Shiloh Shepherds.

BOB'S MOUNTAIN GOLIATH OF ZION at 10 years of age 3/91 - 10/03

This breed came about by a selection process in the larger GSD field, and has been segregated long enough and thoroughly enough to be considered an independent breed. However, this does not materially change genetics.

	The difference that pertains to this article is that in relatively recent years the original and continuing Shiloh Shepherd club, Shiloh Shepherd Dog Club of America, Inc. (SSDCA) and registry, International Shiloh Shepherd Registry (ISSR, Inc.) have always allowed white dogs in the Shiloh gene pool as can be seen by some of the ISSR's giant whites like Goliath and Mygic. A couple of other registries also breed white to colored dogs but continue to call them all GSDs. In dealing with the genetics of the white dog, we will not include the color of the nose bulb or other “integument” because pigment in the nails, nose and pad leather,
HIGHLANDERS MR MYJESTIC-O-ZION at 1 year DOB 2/2000
eyerims, lips, and anus is unrelated to coat pigment inheritance. Nor will the subject of “white markings” be covered here, as that is also a separate genetic pathway we can walk at another time.

	There can be a choice of what sub-type of gene is at that locus, so we have to distinguish between them. The most dominant allele (version or variety of that particular gene) is normally capitalized. Thus, for the pattern genes, we give the capital-letter “A” to the dominant, which in the GSD is “sable,” meaning a relatively uniform all-over coloration that has black hair tips so the coat looks like a light or medium shaded dog that has been stroked with a soot-covered cloth or glove. Sables usually have much less black tipping on the legs and underparts than on the neck, back, and sides. To designate that we have a gene for sable, we use a superscript “y”, which is placed upward a little, like an apostrophe would be.
Zion's Charming Chester DOB 11/23/2008 at 1 year		NS CH Megan's Last Miracle of Zion DOB 2/9/2007 at 2 years

Depending on whether the printer or computer this article is sent to can “read” my superscripts, it will look like this: A^y. That means that at the A locus, there is the configuration of the DNA that calls for sable.

The gene calling for the saddle-marked B&T that is the most commonly seen coat pattern in GSDs is given the designation a^s. The “s” could mean “saddle.” If you see a^t, you can remember this “t” as meaning “tan points” — a “bi-color” dog with Rottweiler type markings. We’ll leave the solid black pattern for some other day.

Now, you need to remember that nearly all cells have two genes of the same general type in each locus. The exception is in the sex cells, sperm and ovum, which each carry only one of the pair. Otherwise the number would double with every impregnation! If both members of the pair are the same, the animal is said to be homozygous for that trait; if the pair is made up of two slight variations, it is heterozygous. A homozygous sable has AyAy at this locus, meaning it cannot contribute to its offspring any pattern gene other than Ay. If the pup is to get something else for the other half, it will have to come from the other parent. A dog that has Ayas is still going to be a sable in appearance, though perhaps not unquestionably… the recessive gene, from the other as (B&T) or at (bi-color) parent might have just enough influence to “show through” a little and give a hint of its genotype presence (not always, though). There are some heterozygous sables that have so much black tipping on the back that people wonder if it is a black-and-tan with a lot of “grizzling” or lighter undercoat showing.

Vision's Carolina Ander Amore DOB 12/3/06 at 1 year

A different locus on the coat-color chromosome is given the E designation, and you can consider that to stand for “extension” or “expression” of color in the hair. Usually a capital letter is used for the most dominant member of each gene family. The E locus either demands (EE), allows (Ee), or denies (ee) the expression of color in the hair. In other words, these alleles affect the production or non-production of pigment granules in the medullae (centers) of the hair shafts. No matter what the dog has at the A locus, the rank of the E-cop at the corner is going to tell the A-locus genes whether or not they will be allowed onto the highway (become visible). So you can have a dominant coat-color pattern (sable, meaning black tips) but an “ee” traffic cop that doesn’t allow it any access, so what do you have? A dog with no color in the hairs. A white dog. A white sable.

This prohibition is not always 100 percent, because of the action of what we call “modifying genes” and by the interactions of various genes. So, fairly frequently we see a white dog with “biscuit” (very light tan) coloration on ears, withers, and perhaps along the spine a ways. Don’t worry about modifier genes on distant loci unless you are breeding strictly for color.

A litter was brought to my attention that had a white-looking sire, “Scout” and a saddle-marked B&T dam, “Elf”. However, the litter included some B&T whelps and some sable whelps, all with normal color as you might see in any litter produced by a sable and a B&T. Now, the only way you can get sables is to have a sable parent (or two). So the breeder and friends were confused. I told them that, to a geneticist, the answer was “plain as the nose on your face” though not obvious to those unfamiliar with the science. The “white” dog (and it is indeed phenotypically white, as I have its picture, and can see only a narrow buff-cream band on its back and a little shade of cream-tan on the back of the ears) is genetically a sable whose black pigment has been inhibited from ever developing because of that “ee” traffic-cop pair of genes.  (View the pedigree of the "Elf/Scout" litter)

Another set of pictures of Shilohs shows the “Gem/Quest” litter born to a light-colored sable and its a^t (bi-color) or a^s (saddle B&T) partner. The reason I am not sure which the latter is, is because the dog pictured is sitting on its hocks, where a clue might be found. It could be a dog with the heterozygous a^sa^t genotype or it could be a^ta^t. No matter. None of the pups were typical sables, despite the fact that sable is a dominant pattern and is usually expected when one parent is. However, remember that the distribution (percentages of each pattern) is an average, and it is possible that one litter can be all sables and the next litter from the same dogs can be all B&Ts.   (View the pedigree of the "Gem/Quest" litter)

But one pup was phenotypically white... why? Neither parent had a phenotype of that color (white). The answer lies in the fact that each parent has one copy of the “e” allele at its E locus. That is, both were Ee there, and when you put two of those combinations together, you can get some EE, some ee, and more Ee. The white dog was ee, meaning that it had genes for not allowing expression of pigment. It is probably a genetic sable, but without color being expressed, one can’t be positive… it could as well be a B&T or a bi-color, but since the ee gene refuses to allow color to be shown in the hair shafts, we don’t know for sure until it is given a test breeding.

Ajax, pictured at 11 weeks

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Copyrighted by Fred Lanting, (Mr.GSD@netscape.com or Mr.GSD@Juno.com or search the Internet)

Reprinted with kind permission of Fred Lanting, author of  The Total German Shepherd Dog and Canine Orthopedic Disorders (both available from the author, autographed).
  Both are expanded and enlarged second editions, a "must" for every true lover. Most of the chapters in each book are applicable to all breeds. The GSD book has, in addition, information specific to the breed. The huge Orthopedics book covers hip dysplasia (HD) and problems in all other joints. A must for anyone considering breeding or buying. Comprehensive regarding optimum diagnosis, treatment, and prevention.

Article reprint permission available. See also: siriusdog.com/sphider/search.php?query=lanting&search=1 for additional Internet articles on various dog topics.