However, Coyle insists no date has been put on the 24-year-old's recovery.
Michael Owen spares Kevin Keegans blushesManchester City v Bolton: PreviewArsenal told by Bolton Gary Cahill will cost £20 millionLiverpool and Rafa Benitez go crazy and Manchester City insult Joe KinnearCahill, who had been tipped to win a place in England's World Cup squad this summer, is now recovering at home after being discharged from hospital.
Coyle said: "I never gave up hope anyway. I said we suspected he would be out for a period of time, probably a couple of months.
"Then obviously because in a couple of months there's not long to go, it all of a sudden became he's out for the season.
"All I would say is, first and foremost, we are doing everything we can to help Gary.
"Once we know his wellbeing is assured we will look at the football side of things.
"He's very comfortable at home, albeit he can't do anything in terms of physical exercise, which is right.
"We'll revisit it in a couple of weeks, have a word with the specialist and see where he is at with it."
Former England U21 international Cahill, a £5 million signing from Aston Villa two years ago, had been one of Bolton Wanderers' most consistent players this season.
The club first became aware of his problem when he was forced to pull out of last Saturday's Premier League draw with Fulham on the morning of the game.