Genetic origin and mechanism

Chestnut generally corresponds to the recessive e/e genotype at the Extension locus involving MC1R. Black eumelanin production in the hair is greatly restricted, allowing red-to-yellow pheomelanin to dominate.

Development and variations

Sunlight, season, nutrition and coat length may temporarily alter the shade without changing the genetic base color.

Possible confusions

Dark chestnut may resemble seal brown or sun-faded black. The absence of true black mane, tail and lower legs is the main distinction.