Coach Romeo Crennel provided the update, but didn't have any further details on Boss' injury following the game. Crennel added that cornerback Javier Arenas also hurt his neck.
Boss was hurt after making a 29-yard catch over the middle in the second quarter. Stumbling backward, Boss was falling down when Buffalo safety Da'Norris Searcy's forearm hit the back of Boss' head. The tight end's head then hit the ground hard.
Boss stayed down for a few minutes before walking off the field under his own power. He sat on the bench for a few minutes, and was then escorted to the locker room before half time.
Searcy was penalized for unnecessary roughness for the hit.
The Chiefs are off to an 0-2 start for the sixth time in seven seasons, and next play at New Orleans next weekend.
Bills coach Chan Gailey had no significant injuries to report following the game.
He said defensive tackle Marcell Dareus continued playing despite hurting his shoulder. Safety George Wilson returned to play in the second half after sustaining a blow to the head while trying to tackle Boss in the second quarter.