Hardy was limited in the second half. He missed the first drive of the third quarter because of an asthma attack.
"Had it my whole life," Hardy said of asthma.
He said he keeps an inhaler with him, and when he returned to the sideline he was seen taking in oxygen.
"He had a little breathing treatment he was having to get," Cowboys executive vice president Stephen Jones said after the game. "Other than that he's obviously playing hard out there and he needed to get that taken care of, but then came back out. As I said, you saw him, flip on the tape and watch him. Guys are playing hard."
Hardy spent the first five years of his career with the Panthers. He recorded 27 sacks in his final 32 games that he played for them, but also missed 15 games last season, spending the final 14 on the commissioner's exempt list as a result of a domestic violence arrest in the spring of 2014.
While he said the Panthers were a "nameless, faceless opponent" after last week's game against the Miami Dolphins, he hugged teammates and former coach Ron Rivera before the game. After the game he spoke with several former teammates and was carrying the jersey of a Panther into the locker room after the game.
How much did Hardy want to get a hit on Cam Newton?
"Wanted to win," Hardy said. "Honestly, being the competitors we are, if it came down to him hitting me, I'm sure he would be excited about that if I got in the way. That's what makes Carolina great. It's what's going to make us great because we're worried about the next game and getting a win. Period."