LSU’s live tiger mascot Mike VI was on the brink of death because of a large, lemon-sized tumor found last month in his face, but just a week after his radiation therapy, the beloved big cat is showing significant improvement, his doctor said.

The swelling in Mike’s face that displaced his eye has completely subsided, which either could be because of reduced inflammation or because the tumor has shrunk in size, said LSU’s David Baker, Mike’s veterinarian.

The timing of the first-of-its-kind radiation therapy for a tiger could not have been more urgent.

“It’s my perception that had we not done this treatment when we did it, I think in a week or two, it would have been too late,” Baker said. “So it was good that we did it.”

But Baker, who personally selected Mike as a cub to be LSU’s next mascot, continues to stress that Mike’s prognosis is still terminal, and he is expected to die in one or two years.

“Will it be six months? Will it be eight months? Will it be two years and two months?” he asked rhetorically. “There’s no way to know.”

Mike was diagnosed with spindle cell sarcoma on the right side of his face May 12, which might be the first such diagnosis for a tiger

His treatment officially took place June 1 at the Mary Bird Perkins-Our Lady of the Lake Cancer Center. But a few days before, on May 28, Mike made an early trip to the doctor’s office so his face could be scanned by the equipment to identify the location of the tumor for the eventual targeted therapy.

The logistics of twice getting a 420-pound tiger transported from LSU to the cancer center — a center for humans — were complex and labor intensive. His treatment happened after hours, so no patients were being seen at the cancer center.

But the medical teams at LSU and Mary Bird Perkins both characterized the visits as successful and without any unexpected incident. “The procedure went about as smoothly as it could have possibly gone,” said Jonas Fontenot, chief of medical physics at Mary Bird Perkins.

The radiation therapy itself was about six minutes long, but on both occasions, Mike spent about an hour at the facility being transferred to the equipment and put in place on the machines.

Fontenot described it as a “surreal, really unique experience,” handling, transporting and treating a wild tiger.

He recalled watching Mike’s motorcade arrive at the center with a police escort. Then, teams of veterinary staff and Mary Bird Perkins staff helped lift a completely knocked-out tiger onto a gurney that is used daily by regular patients.

Lifting the heavy feline took more than eight people and a sling system crafted by the vet staff.

“He was completely anesthetized; he was dead weight,” Fontenot said. “It’s not something we’re accustomed to dealing with. Moving him around, he was much heavier than we expected.”

And to Fontenot’s surprise, the tiger also was much softer to the touch than he expected. He was soft like a kitty cat, he said, not coarse like one might expect of a wild tiger.

“I guess I shouldn’t be that surprised, but the ferocity of a tiger doesn’t lend itself to softness,” he said.

Mike was treated with stereotactic radiotherapy, which uses a beam of X-rays pinpointing the tumor. In the region, about 300 people per year receive the therapy at Mary Bird Perkins. But Mike is the first tiger.

Baker said it was a heavy dose of radiation, but the technology has left Mike’s famous face and hair unscathed in the process.

Baker explained that the tumor is made up of cells that are both radiation resistant and radiation sensitive. The treatment likely killed all of the radiation-sensitive cells, but it left behind the resistant ones. Those resistant cells are temporarily dormant, but they will, at some point, regain strength and start dividing again — growing the tumor to the point where it kills Mike.

He said it’s unlikely — but not out of the question — that Mike would have another treatment because the cells left likely will not respond to radiation if they’ve already survived the treatment. But he said he will continue to confer with medical and veterinary oncologists from within the state and across the country to discuss how to move forward.

Fontenot said treating Mike has a wider impact on the scientific community than just learning about how to treat the next sick tiger.

“Most of what we know about human medicine comes from veterinary medicine,” he said. “It’s not a one-to-one correspondence, but it’s an important tool for us.”

Mary Bird Perkins picked up the tab for the cancer therapy.

Since the treatment, Mike’s eye, which was starting to be pushed shut by the tumor, is back to normal.

“We’re very, very thankful we were able to do that treatment,” Baker said. “Now he’s behaving normal, and he looks great. Nobody could look at that tiger and tell that he has a tumor.”

Follow Rebekah Allen on Twitter, @rebekahallen.