Picked up as a late pick in the
1990 AFL draft (pick 92), Shanahan spent two seasons with St Kilda's reserves before debuting in 1992 with the
St Kilda Football Club. Shanahan played in St Kilda's
1996 AFL Ansett Australia Cup winning side – the club's first AFL Cup win. He was a tall, solid defender and was valuable to the club. Shanahan played in 22 of 22 matches in the 1997 AFL Premiership Season home and away rounds in which St Kilda Football Club qualified in first position for the 1997 AFL Finals Series, winning the club's
2nd Minor Premiership and 1st McClelland Trophy. His peak came in 1997 with the Saints when he performed brilliantly at full-back, but during the 1997
AFL Grand Final he suffered from a goal onslaught by
Adelaide matchwinners
Darren Jarman and
Shane Ellen. Many St Kilda supporters still cringe at then-coach
Stan Alves' refusal to move Shanahan off Jarman, who kicked five last quarter goals to win the Grand Final for Adelaide. ==Melbourne==