"Potentially dangerous dog" means any dog that, when unprovoked, inflicts bites on a human or domestic animal either on public or private property, or chases or approaches a person while off the owner's property, or on the streets, sidewalks, or any public grounds in a menacing fashion or apparent attitude of attack; or any dog with a known propensity or disposition to attack unprovoked, to cause injury or otherwise to threaten the safety of humans or domestic animals. (Ord. 1132,, 1994; Ord. 961, § 1, 1989.)