Sandy Cowan spent most of his lacrosse career with teams from the Canadian province of British Columbia, but was a guest with the Shamrock Lacrosse Club of Winnipeg when they traveled to the lacrosse tournament at the 1904 Summer Olympics. There he helped the team defeat the Mohawk Indians and the St. Louis Amateur Athletic Association to win a gold medal for Canada. At the turn of the century he was a member of the New Westminster Salmonbellies, and won several provincial championships with them, before switching to the Vancouver Lacrosse Club. He retired from active competition in 1911 and later served as lacrosse referee and judge.