Walston (elbow) struck out two and allowed one hit in a scoreless inning during a rehab appearance Wednesday with Triple-A Reno.
Thompson (back) began a throwing program Monday, Alex Weiner of ArizonaSports.com reports.
The Giants transferred McDonald (elbow) to the 60-day injured list Thursday, Alex Pavlovic of NBC Sports Bay Area reports.
The Giants claimed Whitcomb off waivers from the Astros on Thursday and optioned him to Triple-A Sacramento, Alex Pavlovic of NBC Sports Bay Area reports.
Sanmartin struck out two across one scoreless inning in Wednesday's 2-1 loss to the Astros.
Martinez (elbow) struck out two and did not allow a hit or walk in an inning for Triple-A Reno on Tuesday.
Perdomo went 2-for-6 with a run scored in Wednesday's 6-4 loss to the Rockies.
Lawlar (hamstring) could rejoin the Diamondbacks during a road trip the begins Friday in Atlanta, Alex Weiner of Arizona Sports reports.
Carroll went 2-for-4 with a solo home run, a triple and a second run scored in Wednesday's 6-4 loss to Colorado.
Houser didn't factor into the decision Wednesday against the Astros, allowing two hits and a walk across six scoreless innings. He struck out five.
