Dixon left Saturday's preseason matchup with an apparent chest injury and is questionable to return, Jonathan Jones of the Charlotte Observer reports.
In his NFL debut last week, Dixon tallied three tackles against Baltimore. The Washington product has taken reps at both cornerback and safety for Carolina in the early going, but with a lot of uncertainty surrounding Dixon and his injury, it remains to be seen if he'll be able to squeak onto the roster by preseason's end.
Johnson (Achilles) was placed on the Panthers' reserve/NFI list on Monday, Steve Reed of the Associated Press reports.
Johnson also began training camp on the active/NFI list after undergoing offseason surgery to repair an Achilles injury suffered last season with the Patriots. Although no timetable was provided for his return, Johnson could theoretically resume playing after the first six weeks of the regular season.
Brown (leg) is inactive for Sunday's contest against the Seahawks, Mark Dalton of the Cardinals' official site reports.
Recently diagnosed with a sickle-cell trait, Brown will likely be a week-to-week proposition until a solution is found to combat the issue. One more game remains before the Cardinals' bye in Week 9, so it wouldn't shock if he sits out the next few weeks to prepare for the second half of the season. Because Jaron Brown is hindered by a knee injury, wideouts Michael Floyd and JJ Nelson are poised for increased attention from Carson Palmer.