Coach Ron Rivera says Smith is being treated with antibiotics, but the wide receiver's status for the remainder of the preseason is unknown. Smith was seen walking around the stadium on crutches, but was unavailable for comment Wednesday.
Panthers middle linebacker Jon Beason also was held out of practice with a strained hamstring.
The Panthers face the New York Jets on Sunday and then wrap up the preseason the following Thursday against the Pittsburgh Steelers. The Panthers could decide to hold both star players out until the regular season.
Rivera says Carolina's starters will play into the third quarter on Sunday.