720 ILCS 5/48-5

(a) A person commits horse mutilation when he or she cuts the solid part of the tail of any horse in the operation known as docking, or by any other operation performed for the purpose of shortening the tail, and whoever shall cause the same to be done, or assist in doing this cutting, unless the same is proved to be a benefit to the horse. (b) Sentence. Horse mutilation is a Class A misdemeanor.