Coat Color and Pattern in English Shepherds

Black Tricolor
Black tricolor pattern is due to the combined effect of the genes for black/tan pattern and those for white markings.

The black/tan pattern is regulated by the agouti gene locus; this pattern (referred to as "tanpoint") is relatively recessive, so dogs need to inherit two copies of the "tanpoint" allele to display black/tan markings.

The white pattern typically seen in English Shepherds is referred to as "Irish pattern" -- it includes white on muzzle, chest, feet, and tip of tail. These white markings are the result of recessive alleles at the white spotting (S) locus. Dogs that inherit two genes for white spotting will display white markings; their distribution and extent depend on both which alleles they inherit (Irish, piebald, or extreme) and whether any other modifiers are present.

Kuhn's Meggie