Missouri Revised Statutes Title XVII. Agriculture and Animals § 270.230. May be killed, when

If any such horse, mule or jackass be running at large, and cannot be taken up, he may be killed, if notice be first put up at the courthouse door and at three other public places in the county, for ten days, describing the color, marks and brands, as near as practicable, of the animal, and that he will be killed unless taken away and secured.