Scottish midfielder McDonald, who had also been on target in Tuesday's 3-0 win at Oldham, struck in first-half stoppage time with a low drive from the edge of the area after being set-up by Bakary Sako.
Sako turned provider again in the 56th minute with his cross being converted by Nouha Dicko, who grabbed his second goal in three games following his B£300,000 move from Wigan to secure Kenny Jackett's side a fourth successive win.
Bradford, who have now won just once in their last 18 league games, had been up against it after Nathan Doyle was sent-off in the 28th minute for collecting a second yellow card following a foul on McDonald - only eight minutes after his first caution.
Despite their lack of manpower, the Bantams then came close to breaking the deadlock when the unmarked Adam Reach slammed his angled drive off the crossbar from 10 yards out.
Their luckless day was summed up when Stephen Darby struck a post only four minutes before Dicko put the result beyond doubt.