The Lions' secondary has been banged up recently. Safety Louis Delmas (right knee) and cornerback Aaron Berry (right shoulder) were inactive last weekend against Oakland. Cornerback Chris Houston (left knee) played against the Raiders, but the Lions allowed Carson Palmer to throw for 367 yards.
McDonald was released by the Lions earlier this month. He's played in 11 games this season, all with Detroit.
Dawson played in two games with the Lions.
Detroit can clinch its first playoff berth since the 1999 season with a win over San Diego on Saturday.