Two pigments at the base of the coat color of all dogs
Despite the wide variety of coat colors found in dogs, there are only two basic pigments that determine dog color: eumelanin and pheomelanin.
These two forms of melanin are synthesized by melanocytes, pigment cells located in the dog's skin and at the base of its hair.
Eumelanin is a dark pigment, responsible for the black or brown color and pheomelanin is a light pigment, responsible for the red to yellow color. While eumelanin also affects eye and nose color, pheomelanin is produced only in the coat and only affects hair color.
Note!
White dog hair occurs when cells produce neither of the 2 pigments.
Coat color is modulated by genes
If eumelanin and pheomelanin determine a dog's basic color, it can then be modulated by the expression of several genes.
Dog's DNA carries genes that affect the quantity, intensity and distribution of the two types of pigments.
Out of a dog's thousands of genes, only 8 genes are associated with coat color. They are:
- locus A (agouti), involved in the production of both types of melanin,
- of the E locus (extension), responsible for the production of eumelanin,
- the K locus, which governs the distribution of the two types of melanin in the coat,
- locus B which governs the difference between black and brown eumelanin,
- of the D (dilution) locus, responsible for diluting (or lightening) the base color of the dog,
- of the S (Spotting) locus, which governs spotting, i.e. the presence of white spots in the dog's coat,
- of the M (merle) locus, responsible for the presence of variegation found in merle or harlequin coats
- of the H (harlequin) locus which governs the modification of the merle pattern into a harlequin pattern.
Each of these loci functions alone or in conjunction with another locus to control the production and distribution of eumelanin and pheomelanin.
But a dog of a given color can carry "hidden" colors in his gene pool, which are not expressed in him, but may appear in his offspring.