The Irish centre-half has missed the last two matches after damaging the shoulder he had surgery on back in January.
McCarthy will eventually require another operation but has this week been given the all-clear to keep playing as the problem will not get any worse.
But boss Neil Warnock will not risk him on Saturday so Jose Fonte and Claude Davis will continue at the back.
Up front, Freddie Sears is pushing to start after impressing as a half-time substitute at QPR on Tuesday on his return from a groin injury.
Calvin Andrew (knee) is still out while Warnock has allowed young left-back Lee Hills and back-up goalkeeper Darryl Flahavan to join Oldham on loan.