He was expected to be in the hospital for 24 to 48 hours and on intravenous medication, and the team hopes to avoid having to put Schneider on the disabled list.
"They're going to see if that clears it up," Mets general manager Omar Minaya said.
Schneider -- batting .309 with no extra-base hits and eight RBI -- was replaced by Raul Casanova in the starting lineup Thursday night against the Washington Nationals. Left without a backup catcher for the game, New York designated outfielder Brady Clark for assignment and selected the contract of catcher Gustavo Molina from Triple-A New Orleans.
"That put us in a bind and we had to make a player move," Minaya said.
The GM said the infection started to bother the right-handed-throwing Schneider on Tuesday. Schneider played in Wednesday night's 7-2 victory over the Nationals, and antibiotics did not help with the infection.
Minaya said there was no cut or other injury that led to the infection.
Mets manager Willie Randolph said he did not know about Schneider's injury until Wednesday.
"I've never heard of anything like that," Randolph said.
Schneider saw a hand specialist in Washington on Thursday morning, flew to New York for a second opinion, and then the decision was made to hospitalize him.
If the infection responds well to the medication, Schneider could return to the field as soon as he leaves the hospital.
"If the swelling goes down, he should be able to play," Minaya said.
Minaya said OF Moises Alou is making progress in extended spring training at Port St. Lucie, Fla., and could rejoin the team soon. "I don't want to tell you he's day to day, but it's as close to day to day as it can be," Minaya said. Alou, on the 15-day DL recovering from hernia surgery, was 0-for-5 with a walk in extended spring training Thursday. ... C Ramon Castro, who has also been in Port St. Lucie, had a scheduled day off. Castro is on the 15-day DL with a hamstring injury.