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The black German Shepherd can be described in a few different ways. It can appear like the standard solid black Shepherd which is the result of a recessive gene, the dark sable dog that is mostly black because of the effects of modifiers and masks on brown colors, or the black bi-color German Shepherd who may only have a hint of brown points.
However, black also includes its dilute forms of liver and blue in the German Shepherd.
Genes responsible for coat color dictate how eumelanin, which are the blacks and browns, and pheomelanin, the reds and yellows, express themselves.
German Shepherd colors and patterns are mostly the result of a series of genes called agouti, and tweaks in distribution and shades come from modifiers and other series or loci.
Any Agouti expression depends on the “K” and “E” locus, while a recessive gene “at” on the Agouti locus affects the appearance and prominence of a black saddle present in so many German Shepherds.
Evidence of color pattern change can be seen in black and tan puppies which are typically born mostly black and then develop tan markings that spread as the pups mature.
Incomplete dominance of the agouti or “A” series and different modifiers may account for the variations in sable patterns and the amount of black coloration.
Bicolor German Shepherds are black dogs with minimal tan points - they may have tan or red points at the shoulder points in front of the chest and on the paws.
Blue is an expression at the “D” locus of any color German Shepherd. The “D” locus is also known as a dilution gene or bluing gene and has the effect of partially diluting or muting a black coat, causing a charcoal gray to steel blue color.
The “D” series affects eumelanin and, therefore also affects eye color, paw pads, eye rims, the nose, and lips, and blue dogs will have amber, yellowish, gray, or bluish eyes, and a lighter nose.
You may see German Shepherds who are solid blue, blue and tan, and blue bicolor, all for the same reasons as their black counterparts.
The liver, like blue, dilutes black coats. However, the liver color is distinct because it completely disrupts eumelanin, leading to chocolate or reddish-brown coat.
Similar to blue dogs, liver Shepherds have light-colored eyes, usually displaying an amber or yellow color.
Since the liver replaces black, affected dogs can be solid liver, liver and tan, liver bicolor, or liver sable.
Isabella German Shepherds, which in some breeds is known as lilac or silver coloring, have a dilution at both the “B” and “D” locus and represents a muted liver color.
These unusually-colored dogs have light-colored eyes that are often a paler shade than their liver peers.
Other than these genetic variations which affect the colors they display, it should be noted that black German Shepherds won’t differ from standard GSDs in any other way.

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