Kai is an eight-year-old koala who has been battling a fungal infection, called cryptococcosis.

"It's a really nasty fungal infection that usually kills koalas," explains veterinary surgeon Donald Hudson, as he attends to his patient.

Kai was found at Soldiers Point in NSW's Hunter region about 12 months ago with a "hideous bulbous" growth on his head, according to Ron Land, the CEO of care and rehabilitation organisation Port Stephens Koalas, also based in the Hunter.

Ron Land and his wife, Marion, nursed Kai at their home for 16 weeks.

"To keep him alive for a year has been a massive effort," Mr Land says.

"We've come this far, so we're going to give him every chance."

What has increased Kai's chances of survival is a new, state-of-the-art hospital in the grounds of the Port Stephens Koala Sanctuary at One Mile.

The hospital was officially opened in September, replacing a small demountable building, where medical staff and teams of volunteers from Port Stephens Koalas worked to save injured and sick koalas.

That work continues. On this day, there is a line of patients in the new facility, as Dr Hudson, who usually works at nearby Noah's Ark Veterinary Services, and his colleagues hold a twice-weekly clinic.

"We're stepping it up to every day, once we get the staff; it's just getting that busy," says Dr Hudson.

As well as Kai, the patients for this session include Verna, who is to undergo eye surgery, and Willow Sky, who is waiting for a check-up as she deals with anaemia.

Then there's Larry, the blue-tongue lizard, who has a fractured jaw, possibly due to being hit by a vehicle.

Larry is making history. He is the new hospital's first non-koala patient. While it is known as a koala hospital, the facility can treat other native animals, explains Dr Hudson.

First up is Kai, who is receiving a powerful anti-fungal medicine in a saline solution. A line is injected in Kai's lower back area, "where there's nice padding", says nurse Zoe Bradley.

Kai may be uncomfortable as the fluid goes into his body, but the team members reckon it would hurt nowhere near as much as when he was first brought in for treatment.

The cryptococcosis, Donald Hudson says, was "like a ball of jelly" inside the koala's head. That fist-sized ball had to be cut out, and the treatment for the infection continues with the injection twice a week.

"It's been a year now, and it could be another year," Dr Hudson says of Kai's treatment.

Once the line is in, and the 400 millilitres of fluid slowly journeys down the tube and into his body, Kai curls up. Then "he'll get grumpy", adds Dr Hudson.

Alex Cross, the curator of the clinic, keeps an eye on Kai.

"He's handling it okay, but he's not enjoying it," Ms Cross says. "It's something that needs to be done to treat cryptococcosis."

As Kai's treatment will take about an hour, the medical team's attention turns to the next patient, Verna, who is wheeled in by volunteer and senior carer Heather Forbes.

Verna has an eye condition due to chlamydia.

Heather Forbes says the condition has led to a "chunky" area underneath the eyes, so excessive tissue has to be trimmed around an eyelid. Without the treatment, adds Zoe Bradley, Verna "would probably go blind".

Verna is sedated. While that takes effect, Dr Hudson conducts the check-up on Willow Sky. She was rescued in December at Taylors Beach, and she was infested with ticks, causing her anaemia.

The koala is on dietary supplements, including some she's been digging out herself, eating iron-rich dirt at the sanctuary.

The vet is pleased with Willow Sky's progress, saying, "She's good, she's nice and stable."

Dr Hudson is not the only one casting an eye over the little koala

The main area of the clinic has a large viewing window, so visitors to the sanctuary can literally get an insight to what it takes to save koalas.

And at the height of the school holidays, there are many visitors.

The hospital is part of a $10-million complex, funded primarily by Port Stephens Council and the state government, which brings together life-saving medical care and fund-raising ecotourism.

Neighbouring the hospital are rows of "glamping" cabins, and there is also a visitors' centre and raised boardwalk skirting a row of open-air enclosures housing koalas.

The tourism side of the sanctuary helps pay for the care and rehabilitation of the koalas, and visitors can see that at work through the viewing window.

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The clinical team ensures the visitors get more than a glimpse, placing the koalas near the window before and after they are treated.

As Kai wriggles in his basket and Verna slumbers, people peer in, wide-eyed, all the while taking photos on their mobile phones. Among the visitors is Marcella Balestrini and her seven-year-old twins, Camilla and Thomas.

"It's amazing to see so many things that can go wrong with them," Mrs Balestrini says of the koalas' plight. "We know about the bushfires, but there are other things that mean they need looking after."

Her children say they love "seeing a normal koala" through the window.

"It's a key educational process," says Ron Land. "The public sees the sophistication of the treatment, and the lengths we go to keep the koalas alive."

Verna is wheeled into an adjoining surgery, out of sight of the visitors, for Dr Hudson to perform what is a quick procedure. The recovery takes longer, about an hour.

As he places a mask on Verna's face, Dr Hudson says, "We're just going to give her a couple of breaths of oxygen to make her feel brighter." While the koala is attached to a monitor, nurse Zoe Bradley also watches Verna.

"She was giving me a scare before," Zoe Bradley says, explaining Verna was holding her breath, causing her heart rate to plummet. "She's starting to come around now."

The list of patients has lengthened. While Verna was being operated on, Ron Land had walked back into the clinic, saying "another one is coming in and will be here in about 30 minutes". A koala had been found by the road at Salamander Bay, drinking from puddles.

Doug Wheen, a long-time volunteer rescuer, enters with the koala he had been sent to pick up.

"How is his demeanour?," asks Heather Forbes, as she puts on a pair of thick gloves, ready to handle the koala (she has the scars to prove the damage they can do with their teeth and claws).

"Is he aggressive?"

"No, very benign," replies Doug Wheen.

Initially, the team thinks about calling the new arrival "David Bowie", because he has different coloured eyes, just as the late pop icon did. However, when the koala is scanned for a microchip, there is a telltale "beep", indicating he had been in the sanctuary before. Alex Cross checks the database and finds he is named Toohey and had been rescued previously in 2019 before being re-released.

Donald Hudson is not only gentle with his patients but a master of adaptation. To check Toohey's eyes, he shines the torch on his mobile phone, and to encourage the koala to open his mouth for an inspection, Dr Hudson uses a pen.

"He's a young adult," Dr Hudson says.

Toohey will be spending the night in one of the hospital's four intensive care units, where he can be monitored. Heather Forbes grabs a branch loaded with leaves for the koala, once he is placed in ICU.

"There you go," she says to Toohey, who nibbles on a leaf. "That's good to see. He's not feeling stressed, if he's eating."

Donald Hudson is heading outside to check on four more koalas in the enclosures, as the last of the fluid drips into Kai.

It has been a busy hour or so in the clinic. But, as Ron Land explains, it is always busy at the hospital, because the pressure just continues to grow on the local koala populations, as their habitat shrinks and the threats posed by the encroaching humans, from vehicles to dog attacks, increase. "We've been flat out," Mr Land says.

Even before the official opening, on the day the keys to the new facility were handed over in August, the organisation was taking in new koalas in need of help.

But Ron Land only has to look around him at the little patients in the clinic to know the importance of this place, not just for the welfare of these koalas, but for the future of the species in the Port Stephens area.

"All these koalas in here, if they had not come in, they would have died," Mr Land says. "Without a doubt. With their conditions, they would have deteriorated.

"We've got the facilities here to diagnose, treat, and give a koala the best chance of recovery."