The most severe injury is to forward Michael Grabner, who was placed on injured reserve after he was hurt in a 2-1 loss at Boston a day earlier. Coach Jack Capuano ruled out forward Cal Clutterbuck and defenseman Calvin de Haan as well after both were also injured against the Bruins.
De Haan required stitches to close a cut on his forehead after being struck by the blade of a skate during a collision.
Capuano said the defenseman was fortunate he was wearing a protective face shield but did not say how much time De Haan could miss.
Capuano also provided no specifics or timetable on the status of Grabner and Clutterbuck, who both have upper-body injuries.
The Islanders are already playing without their second-leading scorer, forward Kyle Okposo, who is expected to miss at least another month with an upper-body injury.
McDonald had no points in two games with the Islanders in October. Zolnierczyk has yet to play in the NHL this season after signing with the Islanders in free agency last summer.
As for the Sabres, underperforming center Cody Hodgson is in coach Ted Nolan's doghouse.
Saying he's unhappy with Hodgson's play, Nolan announced the player would be the odd man out with forward Marcus Foligno returning after missing 19 games with a hand injury.
"We've got to get more out of him, and right now it's not working, so we'll let him watch," Nolan said. "It's just not working for whatever reason. And when you go through that, you've got to do your own soul-searching and find out what makes you work and fit in."
Hodgson has just two goals and eight points in 51 games this season, after leading Buffalo with 44 points (20 goals, 24 assists) last year. He's in the midst of a 22-game goal drought.