Peralta was placed on the 15-day injured list Monday with a right posterior shoulder strain.
Peralta was removed from Sunday's start against the Nationals in the fourth inning, and he'll land on the injured list after being diagnosed with a strained shoulder. It's not yet clear whether Peralta will be forced to miss more than the minimum of 15 days, but Aaron Ashby is the likely option to take his place in the rotation.