Mo. Rev. Stat. § 430.165: Lien for the care of animals lawfully impounded, who entitled to.

1. Any animal lawfully impounded under the laws of this state or ordinances of any of its political subdivisions may be placed by the impounding officer in the care of any incorporated humane society or other responsible person designated by the impounding authority.

2. Any incorporated humane society or other person designated to care for an animal under the provisions of subsection 1 shall be entitled to a lien on the animal for the reasonable cost of the care of the animal, as provided in sections 430.150 and 430.160.