"Dangerous dog" means any dog that, according to the records of the city, has inflicted severe injury on a human being without provocation on public or private property, or has killed a domestic animal without provocation while off the owner's property, or has been previously found to be potentially dangerous by the animal control officer, the owner having received written notice of such and the dog again aggressively bites, attacks or endangers the safety of humans or domestic animals. (Ord. 961, § 1, 1989.)