Reader (shoulder) was listed as a non-participant on Monday's practice report, Tim Twentyman of the Lions' official site reports.
Reader played 32 defensive snaps and recorded 2.0 sacks in the Lions' Thanksgiving Day win over the Bears. However, it now appears he picked up a shoulder injury in the process. His practice participation Tuesday and Wednesday will likely provide the best indication of whether he can suit up for Detroit's Week 14 divisional matchup against the Packers on Thursday night.