Necropsy findings of koalas from the Mount Lofty Ranges population in South Australia.

OBJECTIVE: This study reports necropsy findings of koalas from the Mount Lofty Ranges region in order to identify health threats to this mainland South Australian population. METHODS: Koalas from the Mount Lofty Ranges region (n = 85) that had died or been euthanased on welfare grounds were examined at necropsy during 2012-13 at the School of Animal and Veterinary Sciences, University of Adelaide. Disease findings, approximate age, sex and body condition of koalas were recorded. Histopathological examination was undertaken on gross lesions and in suspect cases, skin scrapings taken for microscopy and PCR performed for Chlamydia pecorum detection. RESULTS: Traumatic injury was the most common necropsy finding (48/85; 57%), caused by motor vehicle accidents (35/48; 73%), canine attacks (11/48; 23%) or bushfire burns (2/48; 4%). Oxalate nephrosis (27/85; 32%) was also more common than other conditions. Infectious diseases included chlamydiosis (10/85; 12%) and sarcoptic mange (7/85; 8%). Marked testis asymmetry was evident in 11% (6/56) of males, with histopathology suggestive of atrophic change in four animals. Other pathological conditions included gastrointestinal disease (7/85; 8%) and respiratory disease (3/85; 4%). Almost half of the koalas (38/85; 45%) were found to have two or more abnormalities at necropsy. CONCLUSION: This study found trauma, mainly from motor vehicle accidents, and oxalate nephrosis to be the predominant causes of death and/or disease in koalas from the Mount Lofty Ranges region. Recent emergence of both clinical chlamydiosis and sarcoptic mange has also occurred, providing insight into the health status and causes of disease or injury in this South Australian mainland koala population.

The causes and prognoses of different types of fractures in wild koalas submitted to wildlife hospitals.

Fractures are a major problem in wild koalas of great veterinary and conservation importance as their occurrence in different locations of the body might result in varying healing success. The aim of this study was to determine the fracture types (defined by location of the fracture) occurring in wild koalas, temporal patterns, possible causes and risk factors of fracture types, and the prognosis for successfully releasing kolas with healed fracture types into the wild. Data from a total of 2031 wild koalas submitted to wildlife hospitals in South-East Queensland, Australia, over a period of 13 years were analysed. Approximately 56.7% of koalas experienced head fractures, 13.4% had torso fractures, 14.9% had limb fractures and 15% had combination fractures. A total of 84.1% of fractures were caused by vehicle collisions, 9.1% by dog attacks, 3.3% by falls from trees, 1.3% by train collisions, 0.2% by livestock trampling and 1.8% due to unknown causes. Multinominal logistic regression was used to identify risk factors (cause of fracture, age category, sex, year, three-year admission period and season of fracture event) by fracture type. The type of fracture was associated with both the cause of the fracture and the season when it occurred: for example torso fractures (compared to combination fractures) were associated with dog attacks (OR=10.98; 95% CI6.03, 20.01) and falls from trees (OR=4.79; 95% CI2.26, 10.19) relative to vehicle collisions. More submissions of koalas with head fractures due to vehicle collisions occurred in spring compared to autumn and winter, coinciding with the breeding season of koalas and increased animal movement. Prognosis for koalas with fractures was poor, with approximately 63.8% of koalas admitted dead on arrival, 34.2% euthanised, and only 2.0% of koalas able to be released. Given this data, further research into mitigation strategies to decrease the risk of fractures and to increase the observed low recovery rate should be considered.

A retrospective study of admission trends of koalas to a rehabilitation facility over 30 years.

To identify threats to the survival of koalas (Phascolarctos cinereus) in coastal New South Wales, Australia, we compared 3,781 admission records of koalas, admitted between 1 January 1975 and 31 December 2004 to a koala rehabilitation facility on the midnorthern coast of New South Wales, against local wild population demographics, with the use of multinomial logistic regression and chi-square analyses. Trauma, the most frequent reason for admission, affected young and male animals more frequently than other groups. Seasonal differences in the probability of males presenting as trauma cases suggest behavioral factors as an important risk factor for this group. An increasing probability of koalas presenting as a result of motor vehicle accident since 1985 strongly supports the enhanced action of local authorities to pursue traffic-calming strategies if urban koala populations are to be maintained in this area. Koalas with clinical signs of chlamydiosis made up the second most frequent admission group, and these animals were more likely to be aged. This study highlights the potential usefulness of wildlife rehabilitation centers in detailing threats to local wildlife populations, provided record keeping is efficient and focused, and the role of such studies in providing evidence for focusing threat-mitigation efforts. Continual community engagement by koala researchers is important to ensure that maximum benefit is obtained from activities of special interest groups.