Wyo. Stat. § 11-24-104
If any horse or ass not gelded, two (2) years old or upwards, is found running at large, it is lawful for any person to take up the horse or ass and give notice to the owner or keeper if known. If the owner or keeper does not appear within six (6) days thereafter and pay expenses incurred for the feed and care of the animal to the person possessing the animal, the person shall advertise the horse or ass and the same proceedings shall be had as provided in the case of estray animals, or the person possessing the animal may after the expiration of thirty (30) days from the time of advertising, geld or have the horse or ass gelded, at the risk and expense of the owner, except when the horse or ass is in the owner's herd, or in care of the owner's herder. The owner of the horse or ass shall be liable for any damages caused by the animal to property or other livestock.
W.S. 11-24-104