McDavid had a goal and an assist before leaving the game in a 4-0 win over the Mississauga Steelheads.
He suffered the injury during a fight with Mississauga's Bryson Cianfrone, who appeared to slash McDavid in the second period. The 17-year-old junior phenom appeared to slam his right fist into the boards while missing Cianfrone with a punch.
Both players were given five-minute penalties for fighting and McDavid received an additional game misconduct for removing Cianfrone's helmet.
McDavid clutched his right hand as he skated toward the penalty box before leaving the ice. He will see a hand specialist on Wednesday for further examination.
After the game, Kris Knoblauch said he couldn't prevent McDavid from fighting.
"Certainly as a team we want him on the ice, and we want him scoring goals, not (sitting) in the penalty box," Knoblauch said in the Erie Times News. "But you can't hold him back and take the bite out of him. He's certainly competitive and gets angry sometimes. But as a team, we're certainly better with him on the ice."
Knoblauch was asked if a teammate should have intervened.
"I would have liked to, but there was no opportunity for them to," he said. "I don't think anyone was close."
Rookie goaltender Daniel Dekoning, who made 22 saves in his first OHL shutout, said the team was in good spirits after the game. "If something happens (with McDavid)," Dekoning said, "we'll deal with it."
Daniel Dekoning made 22 saves in the shutout for the Western Conference leading Otters (16-1-1) and Dylan Strome had a goal and an assist. Alex DeBrincat and Kyle Pettit rounded out the offence.
McDavid's goal, on a power play at 5:08 of the second period, was his 16th of the season. He leads the OHL with 51 points through 18 games.
Cameron Zanussi made 25 saves for the Steelheads (6-9-1), who dropped their third straight game.