The Rovers defender limped off towards the end of the game at Deepdale and subsequent tests revealed he has suffered a groin strain.
Gordon Greer is standing by to deputise for Mulgrew in the starting line-up after replacing the Scottish international for the final 11 minutes of the game.
But his absence would be a big blow for Rovers boss Owen Coyle, who is already without fellow defenders Elliott Ward and Tommie Hoban for the game.
Jamie Murphy should recover from his groin injury in time for the trip to Lancashire.
The midfielder picked up his groin problem in Friday’s 2-0 home win over Leeds, but boss Chris Hughton hopes the Scot will be ready in time.
Murphy will fight it out with Anthony Knockaert, Jiri Skalak and Solly March for the two wing berths at Ewood Park.
Liam Rosenior will miss out as he continues his recovery from ankle surgery in August.