Md. Code, Business Regulation § 11–635

(a) A licensee may add to any purse in a Fund Race.

(b) A purse, authorized under this part and paid in a Fund Race, is specifically excluded from breeders’ bonuses, purses, or stakes that are paid or offered by licensees in races other than Fund Races, as determined by agreement or formula between a licensee and an organization that represents a majority of the owners and trainers.