Dilutions
Dilution genes are responsible for reducing the amount of pigment produced in coat colors. Some dilution genes affect the entire coat, while others only affect black points. The dilution genes include Cream, Dun, Silver, Champagne, Pearl, Mushroom, and the newly discovered Sunshine and Snowdrop genes.
Cream
The cream allele is a gene which lightens the coat of a horse and affects the skin and eye color in its homozygous form. With a single copy of cream, black pigment is unaffected. A smoky black (CR/n) horse is visually indistinguishable from a normal black horse. A bay horse's coat is diluted to buckskin while keeping its black points, and a red horse is diluted to palomino. In its homozygous form (CR/CR), cream dilutes the coat color on all base coats to a pale cream color as well as creating pink skin and blue eyes. Double dilutes are visually indistinguishable from each other.
Smoky Black
Buckskin
Palomino
Smoky Cream
Perlino
Cremello
Dun
The dun allele is a gene which dilutes the coat color as well as adding primitive markings to the coat (dorsal stripe, leg barring, ear bars, etc.). Additionally, there is a non-dun 1 (nd1) gene that adds primitive markings without diluting the coat color. Dun is considered to be one of the oldest color genes. Black dun horses are also frequently called grulla, named after the Spanish word for crane.
Black Dun (Grulla)
Bay Dun
Red Dun
Silver
Silver is a dilution gene which only affects black pigment at its points. On black and bay horses, the mane, tail, and parts of the legs get diluted to a silvery gray color. Black horses with silver sometimes present with heavy dappling throughout the coat. Red based horses are unaffected by silver, but may still be carriers of the gene. In its homozygous form (Z/Z), silver has been associated with severe Multiple Congenital Ocular Abnormalities (MCOA).
Silver Black
Silver Bay
Champagne
Champagne is a gene that dilutes the coat, skin, and eyes. Red pigment is diluted to a gold color while black pigment is diluted to a tan/brown color. The eyes are amber in color, and the skin is pink or lavender with mottling.
Classic Champagne
Amber Champagne
Gold Champagne
