Each operator of a vehicle approaching a horse on a public highway shall reduce speed, proceed with caution and stop if necessary to avoid endangering the equestrian, or frightening or striking the horse. An operator violating the provisions of this section shall be guilty of a civil violation and, upon conviction, shall be fined not more than twenty-five dollars ($25.00) for the first offense nor more than fifty dollars ($50.00) for second or subsequent offenses.