Dunn (shoulder) was placed on the 10-day injured list Friday.
Dunn left his Thursday start after two innings due to soreness in his right shoulder. Per Corey Brock of The Athletic, Dunn is waiting on the results of an MRI taken earlier Friday. The right-hander spent just over the minimum 10 days on the IL earlier this month due to shoulder inflammation. The Mariners are expected to go back to a five-man rotation for the time being.