It shall be the duty of the Animal Warden or Police Department, without delay, to destroy or otherwise dispose of all dogs not bearing a valid registration tag. Dogs bearing a valid registration tag, other than infected dogs, may be impounded by the Animal Warden or Police Department for a period of not more than three days, including the day impounded and the day released. Any dog so impounded, not claimed by the owner or his or her representative during the time impounded by the city, may be destroyed or otherwise disposed of at the discretion of the Animal Warden or Chief of Police or the official or employee charged with the enforcement of this general offenses code. Any dog, registered or unregistered, which appears to be infected with rabies or other dangerous disease, need not be impounded, but may be destroyed forthwith.