New research sheds light on how koalas may respond to prolonged stress
New research led by CQUniversity has provided fresh insight into how koalas may respond to stress, with implications for conservation, veterinary care and wildlife management.
The peer-reviewed study, published in Veterinary Medicine and Science, examined the physiological response of koalas to high cortisol levels.
Previous research by the team had shown that koalas undergoing treatment for injury or illness did not show the expected decrease in stress hormone metabolites after receiving a glucocorticoid medication.
Lead researcher Dr Flavia Santamaria said that raised an important question.
“Were these unusual stress responses linked to illness and hospitalisation, or do koalas regulate stress hormones differently from other mammals?” Dr Santamaria said.
The current study was designed to ask that question by examining how healthy koalas regulate stress hormones under controlled conditions.
The research team conducted a dexamethasone suppression test on four healthy captive koalas in Queensland, measuring cortisol levels in blood and faecal samples before and after the test. The dexamethasone suppression test is routinely performed in domestic animals and humans.
In many mammals, the test causes stress hormone levels to decrease as part of a normal feedback process. However, the study found that cortisol levels in all four koalas increased rather than decreased before returning to baseline.
Dr Santamaria said the findings suggest that healthy koalas may regulate stress hormones differently to many other species.
“While this was a small, carefully controlled study on healthy animals, the results raise important questions about how koalas cope with prolonged or repeated stress in a changing environment,” Dr Santamaria said.
“Stress hormones play a vital role in short-term survival, but if they remain elevated for long periods, they can affect immune function and overall health.”
Koalas face a range of ongoing stressors in the wild, including habitat loss and fragmentation, disease and climate-related pressures. Understanding how their bodies respond to stress is considered an important part of improving conservation outcomes.
Dr Santamaria emphasised that the findings do not provide definitive conclusions but rather highlight the need for further research.
“At this stage, the study does not conclude that healthy koalas cannot cope with stress,” Dr Santamaria said.
“Instead, it indicates that their physiological responses to stress may be different to what we see in other species and understanding those differences is key to improving veterinary care and conservation strategies.”
The research also has potential implications for veterinary treatment and wildlife care, particularly in how stress and inflammation are managed in koalas during rehabilitation. The research also has potential implications for treatment of common koala diseases, such as cystitis, and for managing stress during rehabilitation.
The researchers said future studies will focus on understanding how stress affects the koala immune system and how this knowledge can be applied to conservation, research and animal welfare practices.
The study was conducted in collaboration with Australia Zoo and involved researchers from CQU’s Koala Research CQ team. The KR-CQ team has decades of experience in Koala research and continue to work towards enhancing koala conservation. The study also followed strict animal ethics guidelines.
The paper 'A Dexamethasone Suppression Test in Koalas Phascolarctos' is available via this link.
