Loper suffered a right hamstring strain in the first half vs. Miami and had been bothered by the injury for the last two weeks. Smith suffered a concussion while attempting to tackle Dolphins fullback Jorvorskie Lane.
Dockery left the game because of personal reasons after opening up as the starter at left guard.
Dockery and Loper are in a battle for one of the final offensive line spots. They signed with the Cowboys early in training camp.