Jess Rendle has worked across animal welfare industries for over three decades, with experience working with production, companion, research, free living and captive wild animals. Her passion for marsupials led to decades of working in zoos, universities, and charities, including undertaking research to better understand the complex needs of this much-understudied group. A proud Anglo-Aussie, Jess continues to support zoos, sanctuaries and organisations across Australia, Europe and around the world.
I first fell in love with Australian native species as a child, with my deepest interest being with the curious group that carried their young in a pouch – the marsupials. Over time, I realised that some marsupial species were at threat of extinction, some becoming extinct in the wild as well as in captivity. And so began my lifelong commitment to better understand and support this unusual group of animals, ensuring their survival for the future.
When I discovered that ‘Benjamin’* the thylacine (Tasmanian tiger), the last of his species, died in captivity, I couldn’t help but wonder why. How could a species die out when cared for in captivity? As I watch the historic footage of ‘Benjamin’ in his barren enclosure, I realise how little was known of how to care for thylacines, and possibly other marsupials in captivity. This lack of knowledge can lead to stress, disease, and in the case of ‘Benjamin’ who reportedly died of neglect, may also lead to the extinction of a species. Nowadays, as we work to conserve species in captive settings, we focus our attention on researching animals in their captive and natural environments, so we can provide them with the best care and welfare. So, how do we ensure the health and welfare needs of other marsupial species are met, whilst in captivity?
Roos in zoos
Kangaroos and wallabies, collectively known as macropods, are a common sight in zoos around the world, yet maintaining them in captivity can be challenging. Specific knowledge of their housing, husbandry, behaviour and health is required, and any deficit may compromise the welfare of the individual, or even the mob (group of macropods). Macropods, like all wild animals housed in captive settings, may be adversely affected by their environment, potentially resulting in stress and subsequent disease. Macropods are known to be affected by a number of diseases, the most notable in captive settings is ‘lumpy jaw’.
‘Lumpy jaw’ – the kangaroo killer
‘Lumpy jaw’ is an incredibly painful and often-fatal disease, and as the name suggest, clinical signs in the latter stages of the disease include swelling of the soft tissue and bony components of head, neck and jaws. In recognition of the progressive nature of this condition, it was recently renamed Macropod Progressive Periodontal Disease (MPPD), however, the disease is still commonly referred to by macropod carers as ‘lumpy jaw’.
‘Lumpy jaw’ has been observed repeatedly in captive macropods and the high prevalence indicates there is an association between the management and husbandry practices used in zoos and the onset of the disease. So, what is it about the way we manage macropods in captivity that increases the risk of them developing ‘lumpy jaw’?
Risk factors for ‘lumpy jaw’
In a five-year study of captive macropods, species, age, stress and enclosure biosecurity were identified as key factors associated with the development of ‘lumpy jaw’. The risk of developing the disease significantly increases with age and those over the age of 10 are at the greatest risk. Juveniles (those under one year) were also not free of risk, regardless of species. The highest prevalence of ‘lumpy jaw’ was found in the red kangaroo and red-necked wallaby, which is no surprise given the popularity of these species in collections around the world. Yet this may be a result of species-specific response to the environment, or resilience to captive stressors. One potential stressor is the internal and external transfer of macropods, however, transfers are essential to manage behaviour problems, manage captive breeding programs or even to visit the vet. Some species, such as the quokka, have been reported to be more amenable to other known stressors, such as visitor presence. The lower prevalence of ‘lumpy jaw’ found in the quokka may indicate the resilience of this species to management-related stressors, including enclosure moves or zoo transfers.
Enclosure hygiene has long been reported as being associated with the development of ‘lumpy jaw’, however, historically these recommendations have focused on the removal of faeces from the enclosure. Visitors in walk-through enclosures and staff entering enclosures, also pose a threat through the introduction of bacterial contamination. Keeper footwear and the sharing of equipment between enclosures, significantly increases the risk of disease developing. So what can we do to reduce the risk?
Key management recommendations to support the health and welfare of captive macropods
The following recommendations for the control and management of ‘lumpy jaw’ in captive macropods have been developed as a result of years of research and are supported by a review of scientific evidence.
- Reduce stressors
- Undertake behavioural training with macropods to facilitate examination of the jaw, head, neck and mouth, without the need for general anaesthetic.
- Reduce the frequency and duration of enclosure moves and zoo-to-zoo transfers.
- Habituate macropods to modes of transport by crate training.
- Manage populations of macropods that are more resilient to stress, avoiding those species with a higher risk of developing ‘lumpy jaw’.
- Minimise other potential sources of stress in captivity such as visitor proximity.
- Increase clinical examinations as macropods age
- The frequency of clinical examinations, specifically those that involve the assessment of the mouth and jaws, should be increased as macropods age. This is especially important for individuals over the age of 10 years.
- Ensure that juveniles are also included in all routine examinations that involve assessment of the jaw area.
- Increase biosecurity measures
- Biosecurity measures should be increased in and around macropod enclosures, including the cleaning of tools and equipment after each use and between enclosures. Better still, use one set of tools per enclosure.
- The implementation of footbaths for keepers to use, and footmats for visitors entering walk‐through enclosures, is strongly encouraged.
Housing macropods in captivity has conservation benefits, including encouraging an interest in native Australian wildlife. However, it is also a privilege. The adverse consequences of disease, such as ‘lumpy jaw’, compromise captive macropod health and welfare, and efforts should be made to prevent this devastating condition. The recommendations above may assist zoos in providing optimum health management for their macropods, undoubtedly having a positive impact on the welfare of the animals. Importantly, it will also assist with the conservation of Australia’s iconic animals for future generations to enjoy.
*The sex of the last thylacine is under debate and although ‘he’ was given the name of ‘Benjamin’ and referred to as male, some believe the last thylacine may have been female.
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