Derby-dog

a masterless animal, who is sure to appear as soon as the Epsom course is cleared for the great race of the season. No year passes without a dog running between the two dense lines of spectators and searching in vain for an outlet, and he is almost as eagerly looked for as are the “preliminary canters.” It is said that when no derby-dog  appears on the course between Tattenham Corner and the judge's box, just before the start, a dead-heat will take place between all the placed horses.