The club's losses have more than doubled to £35.4million, with their debt rising from £64million to £93million, and Gartside said England defender Cahill may be sold in the January transfer window if they receive an offer in excess of £15million.
Gartside, also a long-serving FA board member, said wage restraints were needed.
He told Bloomberg: "Owners should be allowed to invest in equity. So if you, as an owner, want to buy a striker for £10million that shouldn't be a problem.
"But what you then can't do is pay him extortionate wages that take you out of the break-even situation.
"We are carrying too many on the wage bill.
"To be fair, nine players are out of contract in the summer, within them heavy earners, and we'll decide if we want to offer them new contracts."
Gartside said the transfer window may be the best time to receive an offer for Cahill.
He added: "If a Champions League team knocks on our door in January that's the best time to sell an asset because Champions League teams will pay the money."
On 29-year-old Swedish striker Elmander, Gartside said: "He's out of contract at the end of this season and again if someone knocks on the door in January then that's obviously a consideration we have to make."
The Bolton chairman also believes the Premier League's chief executive Richard Scudamore wants even tougher rules on club finances.
"Richard's keener than anybody," Gartside said. "I think he's concerned as much as anybody about the financial state. We keep upping the income and we keep losing more money. It's ridiculous."
Bolton's financial position is not as precarious as was Portsmouth's when they went into administration owing more that £120million because the Wanderers' owner Eddie Davies is owed the bulk of the debt.