Wis. Stat. § 173.12: Animal fighting.

Any veterinarian who has reason to believe that an animal has been in a fight in violation of s. 951.08 shall report the matter to the local humane officer or to a local law enforcement agency. The report shall be in writing and shall include a description and the location of the animal, any injuries suffered by the animal and the name and address of the owner or person in charge of the animal, if known.