McGuire felt some discomfort in the area during his last outing on Aug. 7. He pitched through the pain and struck out eight batters, but the Blue Jays opted to place him on the DL for precautionary reasons.
"He's fine," Blue Jays general manager Alex Anthopoulos said. "If it was the playoffs, he'd pitch, but why take the chance?
"It's more of just giving him a week off of not throwing just to let it totally subside, and then get back to pitching."
McGuire could miss a total of three to four starts, but he is expected to be back in action later this month. The 22-year-old is 2-1 with a 4.82 ERA in three starts with the Fisher Cats this season.
Anthopoulos also confirmed on Sunday afternoon that top catching prospect Travis d'Arnaud would remain in Double-A through the end of this season.
d'Arnaud has been praised for his defensive work behind the plate and is also hitting .326 with 17 home runs and 61 RBIs in 97 games.
Anthopoulos believes it is important for the 22-year-old's overall development that he remain in Double-A. d'Arnaud played just 71 games for Class A Dunedin in 2010 because of a lower back injury.
"He didn't really get a full season in the Florida State League last year," Anthopoulos said. "There was even talk coming out of Spring Training, should we let him at least start in Dunedin, because he missed so much time and didn't get that many at-bats.
"He has been unbelievable in New Hampshire and just for him to get a full season there, to experience playoffs, they've got a very deep team, very good rotation there, great staff, it's a great experience for those kids."