PDFWAC 260-16-040
Washington-bred horses.
(1) To encourage the breeding of horses in the state of Washington, at least one race per race day at Class A, B, and C race meets, whether advertised or not, shall consist exclusively of Washington-bred horses. (RCW 67.16.070)
(2) Only horses certified as Washington-bred, are eligible to run in a Washington-bred only race.