In counties having a population of eighty thousand or more inhabitants and cities of the first class contained in such counties, whenever complaints are made to the poundmaster or the person or corporation performing the duties of poundmaster that a dog is at large, it shall be the duty of such poundmaster, person, or corporation to investigate such complaint. If upon such investigation it appears that the complaint is founded upon facts, it shall be the duty of such poundmaster, person, or corporation to take such dog into custody and he, she, or it may file or cause to be filed a complaint in the county court against such person, firm, partnership, limited liability company, or corporation owning, keeping, or harboring such dog charging a violation of section 54-601 or 54-608.