Between 1982 and 1995 Sloan made 149 senior appearances for Ireland. He represented Ireland at Under-18 and Under-21 levels before making his senior debut. Sloan was a member of the Ireland team that were silver medallists at the 1978 EuroHockey Junior Championship. Other members of the team included Stephen Martin, Jimmy Kirkwood and Billy McConnell. On 18 June 1982, aged 20, Sloan made his senior debut for Ireland in a 7–0 win against Sweden during a EuroHockey Nations Championship qualifying tournament. He subsequently represented Ireland at the 1983, 1987, 1991 and 1995 EuroHockey Nations Championships. He also played for Ireland at the 1985, 1989 and 1993 Men's Intercontinental Cups and at the 1990 Men's Hockey World Cup. On 3 July 1987 he captained Ireland for the first time in an 8–1 win against Belgium. In July 1995 he captained Ireland for the 100th time in a 4–0 win against Italy. In total he captained Ireland on 107 occasions, including at the 1990 Men's Hockey World Cup and at the 1995 Men's EuroHockey Nations Championship when they finished 5th.