Horn (elbow) struck out a batter and worked around two walks in a scoreless inning of relief Wednesday for Triple-A Toledo after being reinstated from the 7-day injured list.
Horn missed just under a month of action for the Triple-A club while he recovered from left elbow inflammation. The 27-year-old southpaw holds a spot on the Tigers' 40-man roster and previously made one relief appearance for the big club in April, but he'll likely stick around in Toledo for the foreseeable future.