Dunn was originally from the West Coast but moved to Christchurch to play for Papanui in the Canterbury Rugby League competition. He made the Canterbury side in 1967 and played for Southern Zone against Northern Zone and New South Wales Country. Dunn played for the New Zealand Kiwis in the 1968 World Cup. He was selected for the 1969 New Zealand under-23 tour of New South Wales but had to withdraw due to injury.
- Coffey, John. Canterbury XIII, Christchurch, 1987.
- DUNN, Spencer - 1968 nzleague.co.nz