The Colts lost quarterback Kerry Collins to a concussion on Sunday against the Pittsburgh Steelers.
The Colts now have Orlovsky, Curtis Painter, Collins and injured quarterback Peyton Manning on the roster.
Orlovsky was cut by the Colts on Sept. 3.
Orlovsky has played in 13 career games with the Detroit Lions and Texans.
He went 0-7 as a starter in Detroit.
For his career, Orlovsky has passed for 1,679 yards, eight touchdowns and eight interceptions.
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Colts add QB Dan Orlovsky
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