Whether a horse’s whorl (the hair that swirls on his forehead) swirls clockwise or counterclockwise can tell you whether he is right- or left-hoofed, according to a November 24 article published in Nature News.
According to the article, veterinarians Jack Murphy and Sean Arkins of the University of Limerick, Ireland, recently authored a research paper titled “Facial hair whorls (trichoglyphs) and the incidence of motor laterality in the horse.” In the paper they “classified a total of 219 racehorses, show-jumpers and eventers as left- or right- hoofed based on the judgment of expert riders as well as on tests such as which hoof they led with when beginning to walk, and which side they chose to go round an obstacle. Of 104 left-hoofed horses, the researchers found that 78 or 75 percent had anticlockwise hair whorls. And out of 95 that favored their right side, 64 or 67 percent had clockwise whorls.”
The article makes the point that which direction a horse favors could help trainers produce stock that runs straighter and wins more races. “That is a strong enough link to be a useful tip to trainers,” Murphy told Nature News. “A horse's handedness or 'motor laterality' translates into a tendency to drift in one direction, which can make a big difference to a horse's competitive chances. The earlier you can spot biases, the easier it is to correct them, by, for example, getting horses to work on their weaker side using longeing.”