Triple-A El Paso placed Otto on its 7-day injured list Sunday with an unspecified injury.
Otto remains on the Padres' 40-man roster and began the season on the club's 15-day injured list while recovering from a right teres major strain. After Otto made five rehab appearances between El Paso and the rookie-level Arizona Complex League, the Padres activated him from the IL and optioned him to the Triple-A club. Since then, Otto had made six appearances for El Paso and struck out 11 over 8.2 innings while giving up three earned runs on eight hits and six walks, but he's now been shut down again with an injury. It's unclear whether he's dealing with a setback related to the previous shoulder issue or if he's tending to a new concern.