Los Angeles Dodgers pitcher Tom Koehler (shoulder) threw a bullpen session on Thursday. He is currently working his way back from a right shoulder injury he suffered during spring training. It's unclear when Koehler plans to begin his rehab assignment, but he isn't expected back until at least mid-June. He'll likely fill a long-relief spot in the bullpen unless an injury opens up a rotation spot. He should be left on the waiver wire.