Shanahan rearranged the team's schedule, holding an early practice so players could go home and celebrate Thanksgiving.
Shanahan acknowledged Wednesday a concern that Landry, the team's best defensive player over the first half of the season, might not play again this year. Landry's left Achilles' tendon is inflamed, and he can't run because of the pain. The team signed former Philadelphia Eagles safety Macho Harris on Tuesday.
"We really have no choice but to rest him," Shanahan said of Landry. "If you play through that pain, there's a chance of rupturing the Achilles', and we don't want to do that."
Running back Andre Brown, a 2009 fourth-round draft pick by the New York Giants, was added to the 53-man roster Thursday. Brown had practice-squad and roster stints with the Denver Broncos, Indianapolis Colts and Carolina Panthers this season before the Redskins signed him off the Broncos' practice squad.
The Associated Press contributed to this report.