Treanor is in Monday's lineup against the Twins, batting sixth. He returns from a strained posterior cruciate ligament in his right knee suffered as he clipped Los Angeles Angels first baseman Kevin Frandsen while running to first on July 23. He was put on the DL the next day.
Treanor was hitting .225 with five homers and 23 RBIs at the time of the injury. He appeared in five rehab games for Oklahoma City through the weekend and was 3-for-15 with two runs scored and two RBIs and didn't have any setbacks.
Treanor gives the Rangers another veteran option at catcher to go along with Bengie Molina.
Teagarden, who is from the Dallas area and played college baseball at Texas, is expected to be an immediate call-up on Sept. 1, when rosters expand. Teagarden, 26, played much better in his second stint in the majors in 2010 than he did to start the season. He hit .246 (7-for-29) with four homers and six RBIs as Molina's backup the last month.
Feldman was taken out of Saturday's game at the start of the seventh inning when the knee was bothering him in warm-ups. He's 6-9 with a 5.43 ERA in 129 1/3 innings pitched this season.
Harden was out with right shoulder tendinitis, his second DL stay this season. He struck out 10 in a rehab start for Oklahoma City on Wednesday.
Harden had made two starts for Texas since his first DL stint from June 12-July 30 with a left gluteal muscle strain. His last start for the Rangers was Aug. 7 at Oakland, taking the loss while allowing three runs in 2 1/3 innings.
In other injury news, second baseman Ian Kinsler will have an MRI on his strained left groin on Tuesday to determine the next step in his rehab.
Kinsler said he's anxious to get his minor league assignment under way and get back on the field for a Rangers team that's coming off a 2-5 trip marked by inconsistent hitting.
"There's no point staying around here," he said. "I'm going to try to get back as quick as possible."
Outfielder Nelson Cruz (left hamstring strain), right-hander Dustin Nippert (head contusion) and infielder Cristian Guzman (strained right quad) also are on the DL and headed for minor league rehab stints.
All four could be playing for either Triple-A Oklahoma City or Double-A Frisco by the weekend.
"Every team has gone through it," Rangers manager Ron Washington said of the series of injuries to key players. "You've just got to keep fighting and hold it together. One thing that's good is our pitching staff has been doing a good job. We've got to start supporting them with some runs."