Mo. Rev. Stat. § 340.328

Any veterinary technician duly registered pursuant to sections 340.200 to 340.330 who gratuitously and in good faith gives emergency treatment to a sick or injured animal at the scene of an accident or emergency shall not be in violation of sections 340.200 to 340.330 and shall not be liable in any civil action for damages to the owner of such animal. This section is not intended to provide immunity for acts which constitute gross negligence.