gallop girl
n.— «Grisham, 36 and affectionately known at Selma’s Retama Park as a “gallop girl,” earns her living running thoroughbred horses for owners and trainers to keep them in shape for coming races.» —“Retratos: Gallop Gal” by John Davenport San Antonio Express-News (Texas) Sept. 20, 2005. (source: Double-Tongued Dictionary)