Lord River's Groom Leading a Chestnut Hunter towards a Coursing Party in Hampshire Jacques-Laurent Agasse (1767-1849)

The picture has something of this: cavalry, mammal, horse, seated, equestrian, mare, equine, two, mustang, stallion, people, racehorse, animal, livestock, mane, pony.
Perhaps it’s a painting of a man holding the reins of a horse while another man holds.