Genetic basis of eH allele - is a variant of the MC1R gene (E locus) identified specifically in Cocker Spaniels. The mutation is c.250G>A (p.Asp84Asn) in the transmembrane domain of MC1R. This allele causes a partial reduction of eumelanin pigment production, increasing phaeomelanin synthesis and producing a sable or dirty red coat color phenotype. The eH allele is unique to Cocker Spaniels and has been present in the breed for about 100 years. It acts similar to other reduced-function MC1R variants like eA and eG (domino/grizzle) but has a stronger effect on modifying coat patterns
Pathophysiology - eH allele partially inhibits eumelanin (black/brown pigment) production across the coat. Dogs with the eH allele, especially dominant black genotypes (KB/-), express a sable-like coat with a gradient from golden or red tones to darker tips. This mutation modifies the usual tan point (at/at) or dominant black coat patterns, causing “Cocker Sable”—a paler and partially red-colored coat effect.
Complications - No associated health risks or complications. Purely affects coat color phenotype.
Why This Matters to Breeders and Vets - Knowledge of eH supports accurate coat color prediction in breeding programs. Helps breeders maintain or select for sable coats, which are considered non-standard by many clubs but are preserved by some breeders. Aids genetic testing labs and breeders in interpreting complex color patterns affected by multiple alleles. Vets and breed enthusiasts can better understand coat color variation and its inheritance.