With hamstrings already keeping Matthew Lloyd and Scott Camporeale on the sidelines, Hird is the latest blow in a series of soft tissue injuries at Essendon.
Camporeale is still another two weeks away and fitness staff will not rush the talented midfielder back into the team.
Meanwhile in better news for the Bombers, Dustin Fletcher and Mark McVeigh are likely to return to the side for Sunday’s match against West Coast.
Both players were late withdrawals from the game yesterday, Fletcher with knee soreness and McVeigh with back spasms. Dean Rioli, who was also a late change from the Carlton match will be tested later in the week.
In other news, Aaron Henneman underwent a shoulder reconstruction today and will most likely watch the remainder of the 2006 season from the sidelines.