McDonald, 22, joined Scunthorpe on loan from Burnley on Thursday but complained of a sore back after his first training session and took no part in Saturday's 2-0 derby loss to Doncaster Rovers.
"It is a little bit of bad luck, and we've just got to spend a bit of time with him," said Ian Baraclough, the Iron manager.
Garry Thompson, the winger, and forward Paris Cowan-Hall will both be part of the squad at Deepdale but neither are fit enough to start. Jim McNulty, the left-back, remains absent with an ankle injury.