It shall be the duty of each owner or occupant of premises within the City whereon any dog, cat or other pet animal which may lawfully be harbored or maintained within the City to maintain the pen or other enclosure or place where such dog, cat or other pet animal is kept in a healthful and sanitary condition at all times, free of offensive substances and liquids, at such place and in such manner as not to constitute a hazard to the health or safety of any person or an annoyance to persons in the neighborhood thereof.