SAN FRANCISCO — The Giants announced on Saturday afternoon that right-handed reliever José Buttó will miss the next two to four months after undergoing a successful surgery on Friday to remove a blood clot from his right arm.

Dr. Jason Lee performed the surgery at the Stanford Medical Center, and Lee will meet with Buttó in one week for a follow-up appointment.

“The biggest thing I told him is I thought he looked really good in the cap they put on you,” said manager Tony Vitello. “The main thing is hope for the best and glad he’s doing well. I think him being at home today is really encouraging, and we move on to the next step where he can come back and be stronger. … There was probably some prior stuff leading up to that. He had thrown the ball well, but not as well as he’s capable of. So, push forward and look for him to come back stronger.”

Buttó’s last outing was on Wednesday against the San Diego Padres when he faced eight batters and recorded just one out, walking four batters and allowing four runs. The right-hander’s average fastball velocity was noticeably down, and he was barely touching 90 mph by the end of his outing. He was removed with what was called right arm fatigue.

“I kind of freaked out on the mound, to be honest with you, because I had never heard of the symptoms he was having — and for good reason,” Vitello said. “It’s a pretty unique situation. … Any time off is not good. Two to four months is not ideal, but we’re all familiar with arm injuries that last longer with that.”

The injury bug has bitten San Francisco’s pitching depth over the last month. Along with Buttó, right-hander Hayden Birdsong underwent season-ending Tommy John surgery, while right-handers Joel Peguero (Grade 2 hamstring strain) and left-hander Reiver Sanmartin (right hip flexor) sustained injuries that delayed the starts to their seasons.

Right-hander Jason Foley (right shoulder) is currently on the injured list as well, but the expectation was always that he wouldn’t return until midseason.

Left-hander Sam Hentges threw a live bullpen on Monday as he continues building up from left shoulder surgery (Sept. 2024) and right knee surgery (Sept. 2025). It is currently unclear when Hentges, who signed a one-year, $1.4 million deal with the Giants in the offseason, will begin a rehab assignment. Vitello, though, commented that Hentges feels “a lot more comfortable and a lot more free.”

The Giants’ bullpen has fared well despite not operating at full strength to start the season. Excluding Buttó’s outing on Wednesday, San Francisco’s relievers have combined to allow nine runs over 28 2/3 innings (2.83 ERA) with 31 strikeouts to 11 walks.

“It’s a strange, good feeling to know that there’s troops that are working hard to join the forces, so to speak, and help out,” Vitello said. “But in the meantime, I think it’s almost like the outfielders that went off to the (World Baseball Classic). It provides us an opportunity to give other guys looks. … It’s a challenge. It’s always going to be a part of it. I think there’s depth there, and at the very least, the guys we’ve been (using), when we put them in a good spot and the game’s competitive, they’ve done a good job.”

Worth noting

Infielder Casey Schmitt, who was scratched from Friday’s starting lineup due to lower back tightness, is a “couple of days away from being active out here,” per Vitello. In a related note, infielder Christian Koss got reps at first base during fielding practice on Saturday.