Culhane made his international test debut at the age of 27 on 4 June 1995 during the 1995 Rugby World Cup. The match, against Japan was won 145-17 and is the largest winning margin for an All Blacks side. Culhane amassed 45 points during his debut, a world record for first class test rugby that still stands today, slotting 20 of 21 conversion attempts and scoring a try. He lost his place in the starting line-up for the next match to first-choice Andrew Mehrtens. He then went on to win just five more caps. He currently coaches Rugby Southland in the New Zealand National Provincial Championship.