The Blue Jays also said injured right-hander Aaron Sanchez had a portion of nail removed from his right middle finger during a procedure performed by Dr. Glenn Goldstein in Kansas City. The Sanchez move, due to a nagging blister issue, was made Sunday but retroactive to Saturday.
Happ is coming off a career season in 2016, posting a 20-4 record with a 3.18 ERA and a 1.17 WHIP over 195 innings pitched.
The left-hander exited Sunday's game against the Baltimore Orioles because of soreness in his elbow. He underwent an MRI on Monday and has been diagnosed with inflammation in his left elbow, according to TSN's Steve Phillips.
It remains to be seen what roles the two players will have after their spot starts but if Happ or Sanchez's injuries persist for an extended period of time, John Gibbons and the staff will have to make a decision on who to keep in the rotation.
The Blue Jays recalled right-hander Danny Barnes and infielder Ty Kelly from Triple-A Buffalo.