Having been born and raised in England's west country—an area once the ancient kingdom of Wessex—I'm very familiar with the potent symbolism of the White Horse. The region has a number of images of white horses carved in the hillsides, where chalk lies just beneath the grass, the oldest of these dating back to the late Bronze Age, some 3,000 years ago.
That said, for most of my time in the Thoroughbred industry—now going on for 50 years—I'd never seen, or for that matter, even heard of a white Thoroughbred leaving aside grays that had become white in old age. In truth, although extremely rare, there have probably always been white Thoroughbreds, but they have been registered as gray or roan, so not appearing as white in the records.
The first horse to be registered as white in North America was White Beauty. A foal of 1963, she was born at Herman Goodpaster's Patchen Wilkes Farm in Lexington, Ky., and has since founded a family that includes a number of white offspring. The coloring comes from a mutation in the KIT gene (responsible for providing instructions for making a member of the protein family called receptor tyrosine kinases), and depending on the location of the mutation, can lead to a variety of patterns from pure white to several spotted colors. There are 29 known versions of mutations to the more than 2,000 base pairs in the KIT that are known to result in some kind of white spotting: W2, W5, W6, W7, W12, W14, and W20 (perhaps the least recognized as it primarily expresses as white socks or blazes).
White Beauty and her descendants are the first recorded instance of the W2 mutation. She was sired by a stallion called Ky. Colonel (1946 by Balladier), a high-class 2-year-old and sprinter whose victories included the Bashford Manor and Joliet stakes and the Sheridan Handicap, in which he set a new world-record for seven furlongs. Registered as a chestnut, Ky. Colonel has been described as, "A chestnut sabino with high whites (stockings) and a large white spot on his belly," sabino being another variant of the KIT gene.
Although the alleles that cause white markings arise from spontaneous mutations, and are not related to the gray coat color, it's interesting that Ky. Colonel was out of a mare by Royal Minstrel, a gray grandson of perhaps the most famous of all grays, The Tetrarch. A foal of 1911—and voted the best British-trained 2-year-old of the 20th century—The Tetrarch was born as a chestnut with black patches, but matured into a gray, whose coat was covered with white splotches, hence his nickname "The Spotted Wonder." At stud he suffered from very poor fertility, but sired a number of good horses including the gray Mumtaz Mahal, perhaps the fastest filly ever to race in England and female line ancestress of North American leading sires Mahmoud and Nasrullah. One wonders whether The Tetrarch, by the gray Roi Herode out of Vahren—a chestnut with a lot of white—might actually have been a gray with a W mutation.
Speculation about The Tetrarch and his descendants aside, there had never been a white runner of note since the color had been officially recognized in the early 1960s until the appearance of Shirayukihime, who was born in Japan in 1996. By Sunday Silence out of the imported Topsider mare, Wave Wind (both parents registered as dark bay or brown), Shirayukihime's white coat appears to be the result of a spontaneous mutation to the KIT gene recorded as W14, the first-known of that kind.
Shirayukihime never ran, but among her 11 named foals—10 registered as white and one gray—was the Kurofune filly, Yukichan, winner of the Queen Sho, Kanto Oaks, and TCK Jo-O Hai and voted the NAR Grand Prix Award for best older filly or mare. Yukichan's white daughter, Shiroinger, is dam of the bay Meikei Yell, winner this year of the KBS Kyoto Sho Fantasy Stakes (G3) and Kokura Nisai Stakes (G3). Yukichan's white sister, Marshmallow, is dam of the white King Kamehameha colt Hayayakko, who became the first official white graded stakes winner when taking the Leopard Stakes (G3) last year.
King Kamehameha is also sire of Buchiko, a half sister to Yukichan and Marshmallow. Another bearer of the white coat color (although with black spots), Buchiko won four races without earning black-type, but her first foal is the white Kurofune filly, Sodashi.
A foal of 2018, Sodashi has wasted little time in becoming one of the stars of Japanese racing. She was successful in a newcomers race, the Sapporo Nisai Stakes (G3)—in race-record time—and Artemis Stakes (G3) on her first three outings. On Sunday Sodashi likely claimed the title of Japanese champion 2-year-old filly with a narrow win in the Hanshin Juvenile Fillies (G1) (with her previous mentioned relative Meikei Yell a close fourth).
If Sodashi's coat color is unconventional for a top-class performer, the same can't be said of her pedigree. Kurofone, a North American-foaled son of the Deputy Minister horse, French Deputy, was exported to Japan as a 2-year-old and won six of 10 starts, including the Japan Cup Dirt (G1). Kurofune—a gray incidentally—went on to be a successful sire with 35 black-type winners, six grade 1, including three-time champion Curren Chan. He also appeared this weekend as sire of the dam of Japanese-bred Longines Hong Kong Cup (G1) scorer Normcore.
We've mentioned that Sodashi's third dam, Wave Wind, was imported to Japan from North America. She was unraced, but was out of Storm and Sunshine, winner of six stakes events including the Test Stakes (G2) and Post-Deb Stakes (G3). Storm and Sunshine was the dam of three black-type scorers including graded winner Smile Again and Halo Sunshine, a stakes winner who also took fourth in the Kentucky Derby (G1). The family arrived in North America from Italy, in the shape of the 1964 mare, Malaga. Her half sister, Midinette II—a good winner in Italy—was imported by E.P. Taylor of Windfields Farm and is ancestress of several notable winners in North America, most notably Hansel, who took both the Preakness Stakes (G1) and Belmont Stakes (G1) in 1991. The family goes back to the famous Italian mare Fausta. Purchased as a yearling by Federico Tesio, Fausta won both the Italian Derby and Oaks and produced three Italian Derby-winning siblings.
