Brackett's locker was cleared out after the game and coach Jim Caldwell said he had no updates on any of his team's injuries.
Brackett, the starting middle linebacker, was trying to tackle Ryan Grant on a short gain when it appeared teammate Philip Wheeler came crashing through and hit Brackett's hand with his helmet.
"I didn't see him on that play, I just made the play. I didn't see Gary at all," Wheeler said.
More than a half-dozen trainers and Colts personnel surrounded Brackett, who left for the locker room a few minutes later with a towel wrapped over his right hand and forearm.
The 30-year-old Brackett agreed to a $33 million, five-year deal in the offseason to stay with the Colts hours after he became an unrestricted free agent.