A woman with a blond ponytail and a white hat is riding a white horse, inside a fence with a horned cow.
The woman owns the horse.
Horses are expensive and most people can't afford the land and horse so they will go to a place to rent or ride a horse, so it's unlikely the woman owns the horse.
One doesn't need to owns the horse to ride it.
A woman riding a horse does not imply that she owns of the horse.