The Port Macquarie Koala Hospital announced that the marsupial, nicknamed “Lewis,” was put to sleep after burn injuries it suffered took a turn for the worse.
“We placed him under general anesthesia this morning to assess his burn injuries and change the bandages,” the hospital said in a Facebook post. “We recently posted that ‘burn injuries can get worse before they get better'.”
The hospital said in Lewis’ case, “the burns did get worse, and unfortunately would not have gotten better."
“The Koala Hospital's No. 1 goal is animal welfare, so it was on those grounds that this decision was made,” it concluded.
The marsupial was crossing a road that had erupted in flames near Long Flat in New South Wales last Tuesday when it was spotted by a passerby, who ran and wrapped the animal in her shirt and poured water all over it.
"He just went straight into the flames, and I just jumped out of the car and went straight to him," the woman who saved the koala, Toni Doherty, told Australia's Nine News.
A Port Macquarie Koala Hospital spokesperson told the news outlet the marsupial's feet were "completely burnt," and he had burns on his chest and stomach.
Officials have feared that hundreds of koalas may have perished in the wildfires that have burned through prime habitat on Australia's east coast in recent weeks.
Port Macquarie Koala Hospital President Sue Ashton has previously said a fire in a forest in New South Wales state, located 190 miles north of Sydney, was burning through about two-thirds of the koala habitat. The koala colony impacted by the blaze was particularly healthy and genetically diverse, Ashton said.
The marsupials climb high into trees during wildfires and survive if the fire front passes quickly below them.
Fox News’ Travis Fedschun and the Associated Press contributed to this report.