No person shall own, harbor or keep any dangerous dog anywhere within the City for any length of time. For purposes of this section, a "dangerous dog" shall be any dog which:

without provocation, bites or inflicts serious injury on any person or any domestic animal; or
is owned or harbored or trained primarily or in part for the purpose of dog fighting; or
is owned or harbored on property known for drug trafficking or gang activities; or
has been impounded by an animal control officer for a violation on at least three (3) separate occasions within any twelve-month period.