Mass. Gen. Laws ch. 129 § 45
Every person engaging in the business of dealing in equine animals or auction of said animals and tack shall obtain a license therefor from the director, the fee for which shall be fifty dollars, and such license shall expire on October thirty-first following the date of issuance, unless sooner revoked, provided that the fee for any person licensed under the provisions of section two B of chapter one hundred and twenty-eight shall be five dollars. The director shall, subject to the approval of the commissioner of food and agriculture make rules and regulations governing the issuance and revocation of such licenses and the conduct of the businesses so licensed and relative to the maintenance of premises, buildings and conveyances, the health of equine animals and the method and time of checking and inspection of said animals. The purpose is to prohibit the transportation and slaughter of horses by inhumane means.
Mass. Gen. Laws ch. 129, § 45