What Makes Them White?
You'll see on this site many times that white German Shepherds are just like all other German Shepherds, but the one obvious difference is that they are white. Really, that's the only difference you'll find. So what makes them white?

The Genetics
This is a description of the genetic cause of white in layman's terms. For a more detailed scientific explanation, see the references below.

There are many different gene locations that determine the color/pattern of a dog. Each one of these locations has multiple genes that can impact the color of the dog. At each one of these locations there are two alleles. They may be the same (we call this homogeneous) or different (heterogeneous). If they are the same, that is what the dog expresses on that location. If they are different, the more dominant gene wins but the dog still carries and can pass on the other gene.

A (agouti) - agouti signalling protein (ASIP)
The agouti locus is one of the most important gene locations in the GSD. In simple terms, this is the basic color pattern. From most to least dominant:
  • Sable - called aw
  • Saddle (aka black/tan or black/red) - called at
  • Solid (usually ends up as black) - called a
There may be other alleles here for dominant black, a second kind of sable and possibly bi-color but for our purposes this is sufficient. Each parent has two genes (for example, awa would be a sable that carries black) and each parent passes one of those genes to their offspring.

There are loci that control intensity (making the "tan" be anything from dark red to cream), control if the dog has any ticking or spotting, and several other components of the coat color. There is also a locus that controls for liver and another for blue.

So what causes white coated GSDs? The most recent research shows that it is controlled by a specific locus - E (extension) - the melanocortin receptor 1 (MC1R). The dominant allele here is usually called E and the recessive is called e. It is this e gene that is believed to cause white coated German Shepherd dogs. Dogs that are ee appear white and dogs that are Ee are white factored (but physically appear colored). EE dogs are colored and do not carry white.

We can DNA test for the e allele with reliability to determine if a colored dog is white factored.

Some white GSDs are very white and others have cream or light tan in their coats. We don't know exactly what gene(s) control this but to understand it more we can look at what the Extension locus does. There are two types of pigment in the coats of dogs. Eumelanin is black pigment but can be modified by other genes to turn it brown, blue, etc. Phaeomelanin is red pigment - this could be dark red to light cream. Dogs that are ee on the Extension series cannot produce Eumelanin so they are basically a recessive red. There is some other gene that controls the richness of the red that is as yet not fully understood. Even the darkest white German Shepherds are at most a light tan, never a real red. This implies some kind of linkage of the genes we do not yet understand.

Breeding
Even though we do not know all the details about the genetics, we do know certain things based on breeding. White always functions like a simple recessive. In other words:
  • A white GSD to a white GSD breeding will always produce all white GSDs.
  • A white GSD to a colored GSD that carries white will produce on average 50% whites and 50% colored GSDs. All the colored GSDs will carry white.
  • A white GSD to a colored GSD that does not carry white will produce all colored GSDS but all will carry white.
  • Two colored GSDs that carry white will produce on average 25% colored GSDs who do not carry white, 50% colored GSDs who do carry white and 25% whites.
  • A colored GSD that carries white to a colored GSD that does not carry white will produce all colored GSDs but 50% will carry white.
  • A colored GSD that does not carry white to a colored GSD that does not carry white will never produce whites.
The following chart summarizes the above principles:
Note: When we talk about percentages, that is technically the percentage each pup has of being a specific color. For example, in a white to white factored breeding, each puppy has a 50% chance of being white. For the sake of simplicity we have simply rounded up to 50% of the litter being white even though this is not strictly accurate.

People often ask what color whites will produce when they are bred to colored dogs. It depends on what they carry on the Agouti series - they may genetically be sable, saddle or solid just like any other GSD. The only difference is we can't see it. For example, an ee dog may be awaw (sable), ata (black/tan carrying for black), aa (black) or any other combination of Agouti genes. They appear white but genetically they are sable, saddle or black.

Example Breeding
A black/tan female is bred to a black male. What color puppies will you get? In this particular breeding (a real breeding that did happen, photos below), there were puppies that were black/tan, black and white. How did this happen?
  • Both Mom and Dad carried a copy of the e gene (they were Ee on the Extension series) so while they were colored, they both carried white. (In this case this was known because each had a white parent).
  • Since Dad is black he must only carry that on Agouti since it is recessive. (Dad is aa)
  • Since Mom is black/tan she must carry that on Agouti. (Mom is at?)
  • Since there was a black puppy, we know mom must carry black on the Agouti series. (Mom is ata)
  • Statistically, 25% of the puppies inherited two copies of e (making them ee on Extension) and were white. In this breeding. two of the eight puppies were white.
  • The puppies who were not white (75% of the puppies and in this breeding six out of eight) inherited either black/tan or black from mom and black from dad. The ones that got black/tan from mom were black/tan (ata). The ones that got black from mom were black (aa).
  • Statistically, 66% of the colored pups are white factored (Ee) and 33% are not (EE).
Simple Summary
If this is too confusing, the bottom line is this - white is a recessive gene that operates separately from all other color genes. If a dog has two copies of that gene turned on, the white masks the color. Think of a white tablecloth over a brown table; it does not change the color of the table, just hides it.

Color Paling
But doesn't white cause color paling? That's likely the most common misconception about white GSDs. The myth is if you include whites in your breeding program, you will cause color paling, ticking and dilution in the colored dogs, but this is false. Breeding to and from whites does not cause color paling. Breeding to and from color paled dogs caused color paling.

Some dogs have richer colors - black/red with deep red color, dark sables, etc. Some dogs have paler colors - black/tan or cream, black/silver, light sables, dogs with a lot of ticking in their black. These color variations can be found throughout the breed - even in lines that have no white in them at all. It is simply part of our breed. If you want richer colors, you breed for them. If you are less concerned with color and breed the lighter colored dogs, you will have lighter colored offspring. It's pretty straightforward. If you compare many American show dogs to many European dogs, you will see a big difference in richness of color (European dogs tend to be darker). This is simply a trend in the lines.

So why do whites get blamed? When you breed white to white generation after generation, you have no idea what color you are breeding. You might be breeding black/cream to black/cream. You can't see the color so you don't know. When you eventually unmask the color (breed to colored dog) it might be a paled color. This has led some people to believe that white causes it. Careful breeding of whites - in a program that includes colored dogs - does not need to produce color paled dogs at all. And of course on the flip side, anyone can produce color paled dogs without any white at all.

References