Veikune, a second-round draft pick, has been inactive for five of the past six games. The Browns listed the No. 53 overall pick as out of Sunday's game against Jacksonville on their injury report this week because of a knee injury. Veikune did not record a tackle in the 10 games he was active this season.
Thomas spent the past seven weeks on Cleveland's practice squad after being signed on Nov. 10. A sixth-round pick by Atlanta in 2008, he spent his rookie season on injured reserve before being waived by the Falcons on Sept. 5.
Also, the Browns released defensive back Joe Porter off the practice squad.