Richmond, 30, went 8-11 with a 5.52 ERA in 27 appearances (24 starts) last season. According to a team release, the injury occurred during his preparations for Spring Training, and he will be "monitored closely throughout his revised throwing program" to rehab the shoulder.
The British Columbia native, who was a member of Canada's team in the 2009 World Baseball Classic, will be behind the other pitchers in camp, with his return to the mound dictated by his progress in rehab.
Richmond spent nearly a month on the disabled list last July due to inflammation in his right biceps tendon. He struggled upon his return, going 2-6 with an 8.44 ERA in his final 11 starts.
Ed Eagle is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.