Dawkins aggravated a neck injury in the first quarter. It's the same injury that forced the 16-year veteran to sit out a 41-23 loss to New England a week earlier.
Denver coach John Fox had no immediate update on the status of his players. Denver (8-7) is tied with Oakland atop the AFC West and is still in contention to clinch its first playoff berth since 2005.
The Broncos host Kansas City in their season finale next week.
The Bills' injury troubles worsened, particularly along a patchwork offensive line that's already missing its top player, center Eric Wood.
Left tackle Demetrius Bell hurt his knee in the second half and did not return. Kraig Urbik, who was starting at center, did not return after hurting his right knee in the first half.
With Urbik out, Colin Brown took over at center and was inconsistent in snapping the ball in shotgun situations.
The Bills also lost another tight end, reserve Mike Caussin, who hurt his right knee on a kickoff return in the third quarter. Caussin was forced to start Saturday because Scott Chandler was playing on a sore ankle and Lee Smith was placed on injured reserve last week.
Without going into detail, coach Chan Gailey said the prospects didn't look good for any of the three players being healthy enough to play in Buffalo's season finale at New England next week.
The Bills also lost receiver Brad Smith in the second half with a hip flexor. Gailey did not have an update on Smith.