Cain was scratched from his previous start last Tuesday after cutting his finger while making a sandwich. His DL stint is retroactive to April 24.
Cain was set to rejoin the rotation, having been named Monday's official starter on Sunday, and claiming that he'd be able to pitch without restrictions, a remark echoed by manager Bruce Bochy. However, the team reconsidered Cain's condition and put him on the DL.
Cain, a three-time All-Star, is 0-3 this season with a 4.35 ERA.