Ashby (shoulder) threw 18 pitches during a bullpen session Wednesday, Adam McCalvy of MLB.com reports.
Ashby has been on the injured list since late August due to shoulder inflammation, and Wednesday's throwing session marked the first time that he threw off a mound since sustaining his injury. The southpaw will take two days off before throwing another bullpen Saturday in an attempt to get him ready for a bullpen role once he's deemed ready to return.