Colors of the German Shepherd Dog
There are three a alleles at the agouti locus in German Shepherd Dogs (GSD) and these account for virtually all of the coat color variation in this breed. Sable in GSD is used to denote hairs that are banded with black tips and base and reddish or cream in between. This is a different use of sable than in many other breeds who use sable to mean a predominance of reddish hairs with occasional solid black hairs interspersed. Sable in GSD is caused by the aW or the wild type allele.
Some GSD are also black-and-tan or saddle-tan. This coat color is caused by either an atat or ata genotype. Finally some GSD are solid black. Such dogs have the genotype aa. DNA testing is now available to distinguish all of these alleles. Although most GSD have a melanistic mask, a few do not. Both the EM and E alleles are present in German Shepherd Dogs and therefore the E genotype will also be reported. While uncommon, the E allele has been observed in GSDs reported as white. Testing for the E allele is also available.