All vehicles and substations used in the transportation or holding of the bodies of dead animals, under the provisions of this chapter, shall have a tank or metal lining in the bed of such vehicle or substation, or be otherwise so constructed that the same shall be practically watertight, so that no drippings, or seepage from such dead bodies shall escape from such vehicles while engaged in such transportation or holding; and every such vehicle shall have a bed of such depth and type of construction and equipment that any dead body or bodies therein shall be completely hidden from view of persons using the highways and any public nuisance obviated while being transported or held.