The Redskins have placed Chris Horton on injured reserve, the team announced on Wednesday.
The move ends Horton's season.
Horton suffered ligament damage in his toe during last Sunday's 31-17 loss to the Atlanta Falcons. He was expected to be out 4-6 weeks.
Horton underwent surgery to repair the injury on Wednesday afternoon. He could be sidelined 4-6 months as he rehabs from surgery, according to head coach Jim Zorn.
"It's another major loss, and we're going to shuffle around to find a replacement, but it'll be hard to replace Chris Horton," Zorn said. "We count on him for so many things, not only on defense but also on special teams."
Zorn said the Redskins would turn to Reed Doughty, who has started three games at strong safety this season and has 44 tackles and a sack.
Fred Smoot could move from cornerback to safety, something that he has done periodically this season, Zorn said.
The Redskins could move LaRon Landry to strong safety and insert Kareem Moore at free safety, but Jim Zorn seemed to think that Landry was "pretty comfortable where he's at."
"I don't think there's going to be a lot of changes going on," Zorn said.
The Redskins could also sign practice squad safety Lendy Holmes to the roster for extra depth in the secondary.
Horton played in all eight Redskins contests with five starts. He registered 36 tackles, including two for loss, three passes defended and a fumble recovery.
Taking Horton's roster spot is running back Quinton Ganther, re-signed by the club on Wednesday.
Ganther originally signed with the Redskins on Oct. 20, but was inactive for the team's Week 7 contest against Philadelphia.
From 2006-08, Ganther was with the Tennessee Titans. He spent the majority of 2006-07 on the Titans' practice squad before earning a roster spot in 2008. He had nine carries for 61 yards and caught six passes for 43 yards last year.
-- DECISION AT PUNTER
The Redskins are carrying two punters on the roster, but probably not for long.
Hunter Smith has missed two of the last three games due to a groin injury. Last week, he was deactivated and the team signed Sam Paulescu for the Falcons game.
Paulescu had three punts for a 50.0-yard average.
If Smith is ready to kick on Sunday, then Paulescu will likely be released.
"I'm going to kick both of them through this week because I have a chance to do that right now, but there'll be a move probably on Saturday," Jim Zorn said.
-- FLETCHER, McDANIELS MEET AGAIN
This Sunday's game between the Redskins and Denver Broncos is a reunion for London Fletcher and Broncos head coach Josh McDaniels. They were teammates at John Carroll University from 1995-97.
McDaniels was initially recruited to John Carroll (in University Heights, Ohio) as a quarterback, but he spent the the majority of his college playing career as a wide receiver.
Fletcher and McDaniel graduated from the same college that produced legendary head coach Don Shula (class of 1951).
Fletcher, meantime, has played in 184 consecutive contests, tied for second-most in the NFL with Tampa Bay's Ronde Barber and Indianapolis's Peyton Manning.