A Queensland wildlife sanctuary has saved the life of a newborn koala in a rare, and possibly Australia-first, medical procedure.

A vet at Brisbane's Lone Pine Koala Sanctuary transferred a two-day-old koala joey called Hermit from its ailing mother's pouch and into the pouch of a surrogate mother.

Dr Galit Rawlinson made the risky and life-saving decision.

"He wouldn't have survived, and we know he wouldn't have survived, if we hadn't done this procedure," she said.

Marsupials differ from other mammals with their young essentially born as a foetus that completes its development in the pouch rather than the womb.

Once a koala joey is born, it climbs into the pouch where it attaches to one of two teats and begins feeding on milk.

If all goes to plan, the joey stays in the pouch for six months before emerging to the outside world.

But life began very differently for Hermit.

At two days old and looking like a small pink jelly bean, Dr Rawlinson took Hermit from his mother Zoom's pouch and moved him into the pouch of another koala called Crumble.

"Zoom was the oldest koala at the sanctuary at the time and she started having health issues as she was due to give birth," she said.

"It was a high-risk kind of situation and I really felt that Zoom wasn't going to be there for the raising of her baby unless we did something — we didn't really know if it would work, so it was all really trial and error."

Dr Rawlinson, with Hermit, says she has not heard of anyone transferring a newborn koala before. ( Supplied: Lone Pine Koala Sanctuary )

Dr Rawlinson said it was a delicate procedure.

"I had sterile gloves on and just put my hand in the pouch and basically gently released the joey from the teat and surprisingly it did release and then took it out of the pouch and put Hermit into Crumble's pouch," she said.

Then began the nervous wait to see if Hermit would attach to Crumble's teats.

"I was nervous because he didn't attach to Crumble immediately — it was a long shot but he was where he needed to be and hopefully he would reattach," Dr Rawlinson said.

"We put her [Crumble] back in a tree to rest but I wasn't feeling overly confident to be honest.

"I felt it had a very poor chance of success and checked it the next morning and it had attached and we were so excited — we were jumping out of our skin actually."

Mother died of age-related issues

Hermit settled into his new home and thrived but Zoom died soon after of age-related issues.

"In hindsight, it was the right decision," Dr Rawlinson said.

"She [Zoom] survived for a few months, but not long enough that she would have raised the joey to a size that it would have survived."

Dr Rawlinson has worked as a vet for 22 years and said it was one the trickiest calls she had ever made.

"We took the risk of losing the joey and causing the death of something that you're trying to save, but in this case it worked," she said.

"I haven't heard of anyone transferring a newborn koala before but I believe it has happened with older joeys."

Hermit is happy and healthy and now nearly two years old.

The sanctuary decided to wait to reveal the details of his remarkable start to life.

"We wanted to wait until he was weaned to make sure that everything was the same as any other koala," Dr Rawlinson said.

"He's very personable and very gregarious and when you go into his enclosure he wants to climb on you and in your face — he's got no sense of personal space but we love him."