"He had some stomach pains last night around 4 a.m., and our training staff did a good job getting him and he had the appendectomy at probably 9 o'clock this morning," Fox said. "They'll keep him in the hospital tonight. It's a scope type of procedure, but they caught it. ... It was inflamed, not ruptured, which is a good thing. So he'll start that recovery process."
Fox did not offer a timetable on Wheaton's return to the field.
The Bears envision a large role for Wheaton on offense after the former Pittsburgh Steeler signed a two-year deal that guaranteed him $6 million in 2017.
Wheaton, 26, appeared in only three games last year for the Steelers because of a shoulder injury, but he averaged 17 yards per reception in 2015.
Wheaton's big-play potential is what stands out to Bears general manager Ryan Pace.
"He brings a speed element that we value," Pace said Wednesday of Wheaton, who also ran track as well as playing football at Oregon State. "He can really stretch the field. He's professional. I love his attitude. You know he's kind of the first-guy-in, last-guy-out kind of worker. But really I think the trait that we value when you think of Wheaton is the vertical speed that he can bring to the offense. That's important."
Running back Jeremy Langford (ankle) also missed practice Sunday.