Wis. Stat. § 951.07: Use of certain devices prohibited.

No person may directly or indirectly, or by aiding, abetting or permitting the doing thereof, either put, place, fasten, use or fix upon or to any animal used or readied for use for a work purpose or for use in an exhibition, competition, rodeo, circus or other performance, any of the following devices: a bristle bur, tack bur or like device; or a poling device used to train a horse to jump which is charged with electricity or to which have been affixed nails, tacks or other sharp points.