The Rams (4-3) were already without starting outside linebacker Alec Ogletree (ankle), who is on the injured reserve-designated to return list, and Long, who has missed the past two games with a knee injury.
Quinn has played in 70 straight games since missing the first game of his rookie season back in 2011. The two-time Pro Bowler leads the Rams with five sacks, eight quarterback hits and three forced fumbles this season.
McDonald is the Rams’ third leading tackler, behind Mark Barron and Ogletree, who both have 55. McDonald has 53 tackles, one sack, one forced fumble, one fumble recovery, one pass defensed and one quarterback hit.
Havenstein was the team’s second-round pick, No. 57 overall, and has started every game this season at right tackle.
The Rams will have to shuffle their lineup to fill these spots.
William Hayes will start at left defensive end in place of Long, with Eugene Sims likely to move into Quinn’s starting spot at right defensive end. With McDonald out, second-year safety Maurice Alexander could make his first career start.
Defensive tackle Michael Brockers talked about the Rams’ depth this week.
“I think it’s more important that a lot of guys know what they are doing now,” Brockers said. “Because last year the defense was new, we were just coming in to it, Chris (Long) goes down, a lot of stuff going on. But this year everybody knows what they’re doing, even the guys backing up know what they are doing, can play both positions and play them well. When you’ve got guys like that filling in and knowing what they are doing, there’s no let off.”
The Rams defense has been one of the better units in the NFL this year.
They go into Sunday’s game ranked fifth in points allowed (17.9), sixth in total yardage allowed (328.1), ninth in rushing yards allowed (98.1) and 10th in passing yards allowed (230.0).
Havenstein being unavailable will mean more moves for an offensive line that lost starting guard Rodger Saffold not that long ago. It looks like veteran guard Garrett Reynolds, who entered the starting lineup with Saffold out, will shift from left guard to right tackle. Then rookie Andrew Donnal, a fourth-round pick, will make his first career start at left guard. Or the Rams could keep Reynolds at left guard and use undrafted rookie Darrell Williams at right tackle.