horse in question is often useful: two chestnut-based parents cannot produce a silver bay or silver black. DNA testing can be used in the most difficult cases. "Sooty" palomino: Dark palominos may be hard to distinguish from silver dapples, particularly if the mane or tail of a palomino contain streaks of silver. A true palomino, with a red-based coat, will exhibit yellow or gold tones; a silver horse, in contrast, is by definition black-based and exhibits gray, black or brown undertones. A sooty palomino, like other creme dilutes, may have brown eyes a shade lighter than average, but this is not true of silver dapples. When actual color is in question, pedigree information or a DNA test can help clarify matters. Prevalence Many breeds do not possess the silver dapple gene. The coat color is traditionally associated with the Rocky Mountain Horse and the Miniature Horse. Scandinavian breeds and their descendants such as the Icelandic horse, Nordland Pony, Shetland Pony, Welsh Mountain Pony, Welsh Pony, Swedish Warmblood and Finnhorse are also found in the silver dapple colors. American horse breeds known to have the silver gene include the Morgan, American Saddlebred, Missouri Foxtrotter, Tennessee Walking Horse, and the American Quarter Horse. European draft breeds such as the Comtois and Ardennais also occur in silver. Historically the color was found in the Dutch Groningen, but the breed was crossbred to produce the Dutch Warmblood and underwent subsequent genetic bottlenecking, so the gene may no longer be present. Inheritance and expression The silver dapple trait is caused by a missense mutation (labeled Z) in the PMEL17 gene on horse chromosome 6. It is transmitted by autosomal dominant inheritance (simple dominance). PMEL17 is active from quite early in embryonic development through to the mature cell's melanosome and is involved with the production of the black pigment eumelanin. Melanins, which provide color in the eyes, skin, and hair, are found in two types: eumelanin, which produces black to brown pigment, and phaeomelanin, which produces red to yellow pigment. Most horses can produce both types; the brown appearance of a bay horse's coat is caused by alternating bands of eumelanin and phaeomelanin, for which the agouti gene is responsible. Eumelanin predominates in the legs, mane and tail of bay horses. By contrast, horses which lack a functional agouti gene cannot produce such alternating bands, and thus have wholly black coats with no visible phaeomelanin. Chestnut