Mo. Rev. Stat. § 270.010
It shall be unlawful for the owner of any animal or animals of the species of horse, mule, ass, cattle, swine, sheep or goat, in this state, to permit the same to run at large outside the enclosure of the owner of such stock, and if any of the species of domestic animals aforesaid be found running at large, outside the enclosure of the owner, it shall be lawful for any person, and it is hereby made the duty of the sheriff or other officer having police powers, on his own view, or when notified by any other person that any of such stock is so running at large, to restrain the same forthwith, and such person or officer shall, within three days, give notice thereof to the owner, if known, in writing, stating therein the amount of compensation for feeding and keeping such animal or animals and damages claimed, and thereupon the owner shall pay the person, or officer, taking up such animal or animals a reasonable compensation for the taking up, keeping and feeding such animal, or animals, and shall also pay all persons damaged by reason of such animals running at large, the actual damages sustained by him or them; provided, that said owner shall not be responsible for any accident on a public road or highway if he establishes the fact that the said animal or animals were outside the enclosure through no fault or negligence of the owner. If the owner of such stock be not known, or if notified and fails to make compensation for the taking up, feeding and keeping of animals taken up under the provisions of this chapter, the same shall be deemed strays, and shall be dealt with in the same manner as required by law with respect to such property as strays, under the stray law. Any failure or refusal on the part of such officer to discharge the duties required of him by this section shall render him liable on his bond to any person damaged by such failure or refusal, which damages may be sued for and recovered in any court of competent jurisdiction.
§ 270.010, RSMo
RSMo 1939 § 14463, A.L. 1945 p. 103