(a) It is unlawful for an owner of a dangerous dog to permit the dog to be outside a proper enclosure unless the dog is muzzled and restrained by a substantial chain or leash and is under the physical restraint of a responsible person. The muzzle shall be made in a manner that will not cause injury to the dog or interfere with its vision or respiration but will prevent it from biting any person.

(b) It is unlawful for the owner of a potentially dangerous dog to permit the dog to be outside a proper enclosure unless the dog is restrained by a substantial chain or leash and is under the restraint of a responsible person.