A Chestnut Horse possibly Old Partner held by a Groom James Seymour (1702-1752)

The picture has something of this: horse, mammal, cavalry, equestrian, seated, equine, motion, mare, two, racehorse, stallion, people, livestock, pony, run, mane, race, animal.
Perhaps it’s a painting of a man holding a horse’s bridle with a man in a blue suit standing next to a brown horse in a field.