No person shall leave any guard dog or attack dog unattended in any place in or out of any building unless a warning sign has been placed in a clearly visible location at the premises, located so that it can be seen by any person before entering the place to which the dog has access, warning that a guard dog or attack dog is present. As used in this section, the term guard dog or attack dog means any dog intended to attack intruders, whether the dog has been trained to do so or the dog does so without training. No guard dog or attack dog shall be left unattended in any place except inside a building or out of doors in a fenced yard, with a fence adequate to prevent the dog from leaving the yard. (Ord. 87-173 § 2, 1987.)