It shall be illegal for any person to own, possess, harbor, or offer for sale, any non-domestic animal within the city. Any owner of a non-domestic animal at the time of adoption of this code shall have 30 days in which to remove the animal from the city after which time the city may impound the animal as provided for in this section. An exception shall be made to this prohibition for animals specifically trained for and actually providing assistance to the handicapped or disabled, and for those animals brought into the city as part of an operating zoo, veterinarian clinic, scientific research laboratory, or a licensed show or exhibition.