Newcastle United s Callum Wilson (right) is out of action with a calf injury. AFP
The 29-year-old, who has scored six goals during the current campaign, was expected to be sidelined for around eight weeks after suffering the injury during the 1-1 draw with Manchester United on December 27.
However, Howe has admitted the striker might be missing for significantly longer as Newcastle battle relegation.
Speaking at his pre-match press conference ahead of Tuesday's clash with Everton at St James' Park, Howe said: "It's been slow progress for him since the initial injury. He was recently on crutches -- I think he's come off those crutches now and is walking normally, which is a big step.
"But you can see by that update that I'm giving you it's quite slow, so we all wish Callum to come back as quickly as possible, but when he comes back, he's got to be fit and ready to give his best, so we're helping him with that, obviously, day to day.
"But I don't think it's going to be short-term. Hopefully he can make the last few games of the season and really help us in the key moment."
Wilson's lengthy absence is a huge blow to the Magpies, who invested £25 million ($34 million) last month in Burnley frontman Chris Wood, but failed in their attempts to further boost their firepower as their pursuit of Manchester United's Jesse Lingard and Reims' Hugo Ekitike came to nothing.
Kieran Trippier, Wood, Bruno Guimaraes, Dan Burn and Matt Targett all arrived during the January transfer window and all five could be involved against Everton.
The Magpies are second from bottom of the Premier League table but just a point away from safety.
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