Studies for or after The 3rd Duke of Richmond with the Charleton Hunt George Stubbs

The picture has something of this: cavalry, mammal, seated, two, horse, livestock, people, farm, herder, outdoors, cattle, animal, man, motion, group, equestrian.
Perhaps it’s a painting of a man sitting on a white horse next to a dog and a flock of sheep in a wooded area with a tree in the background.