Zeus the koala might be immortal after all..

Zeus is by far the biggest male koala in our study and had a perfect body condition score when we first captured him, which is pretty unheard of. One way we measure health is by feeling for a bony ridge on the koala’s scapula, which protrudes more as koalas lose condition. I could barely feel this ridge on Zeus as he was so toned and muscular – not quite Arnold Schwarzenegger but pretty good for a gum-leaf eating marsupial. It seemed fitting to name him after a Greek god.

Unfortunately as we monitored Zeus we saw what had started out as a minor eye infection was getting much worse. At one stage his eye closed up completely, and it looked like he must have chlamydia. It’s a common disease that occurs in two different strains in koalas in this area and results in nasty symptoms including blindness, urinary incontinence, sterility and often death.

There is a mixed record of success when it comes to treatment of chlamydia in koalas. Often the stress of being held in care combined with the disease symptoms means they don’t survive treatment. If the koalas are given antibiotic injections, the standard treatment, it can mess with their gut flora and those bacteria are essential for them to be able to detoxify and digest eucalypt leaves, so they can deteriorate further.

So I was pretty nervous about re-catching Zeus and taking him into care for treatment, but we had to try. We caught him and took him to Vickii Lett a local WIRES carer who also works for National Parks. She started Zeus on an eye ointment straight away. Apparently he liked the soothing eye-wash but then rubbed most of the ointment out later. He grunted at Vickii whenever he’d had enough of being interfered with.

Veterinarian David Phalen is a collaborator on our project so we consulted him and he organised testing by the University of Sydney’s Koala Health Hub. It turned out Zeus tested positive for chlamydia and was at risk of urogenital infection as well. So he had to be given the dreaded injections. Apart from his eyes he was still physically fit when he came into care so we hoped he had a good chance of successful treatment.

Zeus and Vickii both suffered several weeks of injections. Zeus suffered the needles, given into a pinch of skin on the back of his neck. Vickii suffered from his attitude; he did not behave like a sedate and sickly koala. Both of them dreaded the injections and Vickii ended up using her husband as a decoy, who would distract Zeus while Vickii approached in stealth-mode from behind, with Zeus grunting and occasionally swiping at her hubby. They all got through it alive and unharmed.

Zeus spent a few extra days in care after treatment waiting for his new test results to come back, and apparently his attitude completely changed; he sat in a more relaxed position and stopped the hostile grunting once he knew the needles had stopped. Not only did he survive the treatment but he ate so well he is one of the few koalas to put on weight while in care. The test results after treatment came back negative for chlamydia, so we made a plan to release him.


Zeus the koala, on release
Zeus the koala beat the odds and was
released back into the wild this week.


Zeus before and after treatment
Before and after: Zeus’s eye infection before
we caught him and took him in for treatment…


Zeus after treatment of his eye infection
Zeus just before we release him, after treatment.


He was so adapted to his new environment that he just calmly sat there while I fitted a new collar to him. It turned out to be lucky for Zeus that he was part of our study as we were able to monitor him and bring him in early, and treat him for another chlamydia strain he was not yet showing any signs of. It’s also quite rare for animals to be monitored after release from care, so it will be good to be able to keep an eye on him (excuse the pun) and see how he goes.

On release Zeus effortlessly climbed a big tree, bellowed to tell everyone he was back, and started eating again. It’s nice to see our big and boofy dominant male back home in the bush again. We’ve all got rather fond of him and his boisterous ways. Zeus had so much attitude while in care that I was going to change his name to Fluffy to take him down a peg, but I guess he has earned the name Zeus after all.

By Dr Kellie Leigh, Executive Director, Science for Wildlife.