The bay horse, left, has both eumelanin and phaeomelanin in her coat; the agouti signaling peptide suppresses black color to the "points" v the mane, tail, ear tips, and legs. The horse at right lacks the agouti signalling protein, and has a uniformly black or aphaeomelanistic coat. In a chestnut horse, the solid red coat is created by a recessive aeumelanic mutation in MC1R and agouti, if present, is masked.