Henry has a left foot injury and is questionable to play when Buffalo hosts Miami on Sunday. He was walking with a limp and was wearing a sweatsuit while watching practice.
Henry was hurt during the first quarter but returned to play in Buffalo's 16-14 loss at the New York Jets last Sunday. Henry has not made himself available for comment since speaking to reporters immediately following the game.
Coach Mike Mularkey said Wednesday he assumed Henry would be ready to play.
Even if Henry dresses Sunday, McGahee is expected to get more playing time because he's the healthier running back.
Buffalo's first-round pick in the 2003 draft, McGahee missed all of his rookie season recovering from reconstructive surgery on his left knee. Limited to a backup role this season, McGahee has had 19 carries for 70 yards, including a season-high 42 yards filling in for Henry against the Jets.
McGahee said Thursday he's not been told whether he'll start and that the decision will likely come at game time.
"I'm just going in there and be ready for whenever my number's called," McGahee said. "All I can do is just wait and see."
A start against the Dolphins would be significant for McGahee, who played college ball for the Hurricanes and is a Miami native.
"It's no biggie to me," McGahee said. "As long as I can get in there and play, because I feel like I can go in there and make a difference."
Mularkey credited McGahee for being more focused at practice and in meetings in the last few weeks.
"Yeah, I've worked a little harder now, just hoping to get my chance," McGahee said. "Sooner or later it's going to be here. I'm not going to rush it. I'm not going to worry about it."
Safety Coy Wire, who missed last weekend's game with a bruised thigh, was upgraded from questionable to probable on Thursday. Left tackle Jonas Jennings (left ankle) missed his second straight practice and is questionable.