Haskell has only been able to make three competitive appearances for Saints since joining the club during the summer.
He has not featured since the Challenge Cup defeat to Clermont Auvergne at Franklin's Gardens on October 13.
And Boyd said: "He's still battling away. He's got a grumbly ankle and had a back injury.
"He's still on the long-term injury list and hopefully we can get him off that list sooner rather than later, but he's making a great contribution around the club anyway.
"It's just a niggly injury that won't go away, it's not an acute injury, it's a chronic long-term thing for him."
Heinrich Brüssow remains a doubt for Saints after his concussion problem forced him to withdraw from last Sunday's Premiership Rugby Cup win at Wasps.
But better news comes in the form of tighthead prop Paul Hill, who appears like to play a part in Friday's game at Gloucester.
"I don't think we took any serious injuries out of the last couple of weeks," Boyd said. "We've got some niggles, like every club has.
"Paul Hill is now available and Toby Trinder played his first game last weekend so we've had a couple of long-term injuries clear up, which is good.
"We've still got a group of guys in the outside backs who are out for a long period.
"Maybe Hutch (Rory Hutchinson) will be back before Christmas but there are still quite a lot of guys out in that space."
Hooker Mike Haywood is available this week after recovering from concussion, sustained in an unfortunate collision with team-mate James Craig.
Craig remains sidelined after that incident in the win against Bristol Bears on October 27.
"He seemingly has been very unlucky and he came back and took a fearful head clash with Mikey Haywood, which is probably not the guy you want to have a head clash with!," Boyd said.
"He's gone back to his protocols after suffering another concussion. He's had a few and he'll just come back quietly when it allows."
Ehren Painter, who signed his first senior contract at Saints earlier this week, has missed the past couple of matches due to a back problem, but he is now close to making a return to action.
"He had a little back spasm that required a bit of attention," Boyd said.
"He's not far away but whether we risk him or not is another thing.
"He's a young man we don't want to put too much load on and with Paul Hill coming back that alleviates that situation.
"And Karl Garside, who has come in from Ampthill, has done a wonderful job to fill a hole for us over this period of time."
Ken Pisi (shoulder), Nafi Tuitavake (neck), Andy Symons (knee) and Harry Mallinder (knee) remain on the long-term absentee list.