In 1943, the live distribution of bison was terminated due to concerns of brucellosis in the herd. Brucellosis testing first took place in 1945 when 85% of 60 animals tested were found to be reactors or suspect. Vaccination and testing continued through 1948. This program was terminated in 1949/50 due to lack of vaccination and testing of adjacent cattle and bison herds. Because of this decision, all corrals were removed.