Modifiers
Modifiers are genes which alter the horse's coat without diluting the color. A few modifiers include gray, flaxen, sooty, and pangaré.
Gray
Gray is a gene which causes progressive depigmentation of the coat with age. Gray horses begin their life hyperpigmented and gradually lose color until they become visually white. The rate of graying is different in every horse, with some turning white within a few years of life while others take over a decade. Gray horses only need one copy of the gray allele to be gray (G/g). Gray is linked to an increased risk for melanoma, with 80% of gray horses developing melanomas past age 15.
Flaxen
Flaxen is a gene that affects red-based horses by lightening the mane and tail to a beige or white color. Currently, flaxen is an undiscovered gene that cannot be color tested. The Haflinger is a breed of horse which always expresses flaxen chestnut.
Sooty
Sooty is a progressive gene characterized by a darkening of the coat over time in red-based and bay-based horses. Sooty is an undiscovered gene that cannot be color tested.
Pangaré
Pangaré is a gene found in red-based and bay-based horses that lightens the coat around the eyes, muzzle, and belly. Pangaré is an undiscovered gene that cannot be color tested. It is most commonly seen in breeds like the Exmoor pony, Fjord horse, and Haflinger. It is also seen in the last remaining true wild horse breed, the Przewalski's horse.
