 On a gray horse, markings visible at birth may become hidden as the horse turns white with age, but markings can still be determined by trimming the horse's hair closely, then wetting down the coat to see where there is pink skin and black skin under the hair.Recent studies have examined the genetics behind white markings and have located certain genetic loci that influence their expression.In addition to white markings on a base coat, there are other markings or patterns that are used to identify horses as with Appaloosa, Pinto or Brindle, as well as artificial markings such as branding.