They're off in a one-mile race at Laurel (MD) Race Course that begins and ends at the finish line. The track was past muddy, almost to flood stage from a day of pouring rain. Racing goes on regardless of the weather. The horses weren't trying to avoid getting their hooves dirty. At the full gallop there is a moment in every stride where all four of the horse's feet are off the ground. It was a coincidence that all but the horse running last had all of their feet off the ground at the same time.