Dalton (undisclosed) left the field in the third quarter of Sunday's contest at Washington after a late hit from linebacker Jon Bostic, The Dallas Morning News reports.
Dalton's helmet was knocked off at the end of his slide, resulting in his departure and Bostic's ejection. If Dalton is unable to return, he'll finish the game 9-for-19 for 75 yards and one interception. Ben DiNucci, the only other QB active for the Cowboys, took over for Dalton under center.