Ontario Highway Traffic act part 10, section 167

Every person having the control or charge of a motor vehicle or motor assisted bicycle on a highway, when approaching a horse or other animal that is drawing a vehicle or being driven, led or ridden, shall operate, manage and control the motor vehicle or motor assisted bicycle so as to exercise every reasonable precaution to prevent the frightening of the horse or other animal and to ensure the safety and protection of any person driving, leading or riding upon the horse or other animal or being in any vehicle drawn by the horse or other animal. R.S.O. 1990, c. H.8, s. 167.