The sheriff of each county of this state shall annually designate, by a record made in the office of the clerk of the county commission, one of his or her deputies to act as humane officer of the county; or, if the county commission and sheriff agree, the county dog warden may be designated to act as the humane officer or as an additional humane officer; any person designated to act as a humane officer and all peace officers designated by law as a humane officer or an additional humane officer shall investigate all complaints made to him or her of cruel or inhumane treatment of animals within the county and he or she shall personally see that the law relating to the prevention of cruelty to animals is enforced. The wilful failure of such designee to investigate any complaint made to him or her and to take proper measures in such case or to perform his or her duty in any other respect may constitute good cause for removal from employment.