Kitna, who couldn't be reached for comment, played in three games during the 2011 season. In his last action, he took a knee to cap the Cowboys' 44-7 victory over the Buffalo Bills on Nov. 13.
Afterward, Kitna struggled to stay active because his back problem never improved. He was hopeful he would return by season's end.
Kitna finished his career throwing for 29,745 yards with 169 touchdowns and 165 interceptions. He saw his most significant action with the Cowboys in 2010 after starter Tony Romo suffered a broken collarbone, throwing for 2,365 yards with 16 touchdowns and 12 interceptions. But he couldn't finish the season after suffering an abdominal injury in a loss at Arizona.
Before joining the Cowboys, Kitna spent three seasons as quarterback for the Detroit Lions.
With Kitna retired, the Cowboys' backup quarterback is Stephen McGee.
Calvin Watkins covers the Cowboys for ESPNDallas.com.