Australian Veterinary Journal最新文献

This study appraises recent research to critically evaluate knowledge on the factors that influence decisions around the release of rehabilitated koalas to fire-affected home sites. Availability of koala release sites could be compromised at times in the future by the increasing incidence of large and intense bushfires due to climate change. In addition, factors such as the fragmentation of koala habitat and increasing urbanisation impose other threats to the long-term survival of the released koala. Our investigation is conducted as a Critically Appraised Topic (CAT) with eight papers selected to be appraised. We highlight three key areas that affect koala rehabilitation and release to fire-affected home sites - the resilience of the koala in recovery, the adaptation ability of the koala upon release and the components of the fire-affected habitat. The evidence shows that the koala is a good candidate for release given that burnt koalas are resilient in rehabilitation and many can recover and then adapt quickly to their release site. Findings from this study indicate that, when the release site is affected by fire, the conditions that are more favourable for koala release are low severity of fire impact, greater distance from urban areas, connection to unfragmented habitat and previous management of predators. These findings can inform wildlife release and rescue as well as government planning and urban development.

This study presents a retrospective analysis of clinical records data from koalas presenting for treatment following the large-scale bushfire event on Kangaroo Island 2019-2020. The aim of the study was to identify prognostic factors for koalas affected by bushfire. Koalas (n = 199) were grouped based on their burn status in combination with their burn bandaging requirement at triage; those with no burns, with burns that did not require bandaging and with burns that did require bandaging. Overall, 59.8% of koalas had positive outcomes, but this reduced to only 13% of koalas in the most severely affected group (burns that were bandaged). Negative outcomes were found to be associated with several factors, including the timing of presentation, with the worst affected animals presenting in the first 2 weeks of the operation. Also, an increasing number of bandage changes during hospitalisation led to increasingly negative outcomes, with no positive outcomes beyond three bandage changes. In addition, clear associations were found with patterns of burns on feet, with only 4% positive outcomes for animals with all 4 feet burnt. All bandaged koalas with severe dehydration had negative outcomes and body weights decreased over time for hospitalised animals from the most severely affected bandaged burn group. Mild serum sodium concentration elevation at triage was the only clinically significant blood abnormality for koalas with bandaged burns. Overall, this study identified key prognostic factors, particularly bandaging requirements and the number of feet burnt, that will enable more effective decision-making at triage and improve animal welfare outcomes.

Objective: To determine the causes of mortality in koalas autopsied at the University of Melbourne based on the retrospective analysis of autopsy reports.

Methods: The autopsy reports of 239 koalas examined at the University of Melbourne from 1970 to 2023 were reviewed to determine which of the comorbidities present was the primary cause to which death could be attributed.

Results: Infectious disease (62 cases) including presumptive chlamydiosis (38 cases), emaciation (38 cases) and trauma (35) were the leading cause of mortality. Death was attributed to other causes in 89 cases, whereas the cause was not definitively determined in 39. Twenty-six different causes of death were identified overall. Presumptive chlamydiosis was the greatest single disease to cause mortality, primarily due to the increased likelihood of leading to euthanasia. Traumatic causes included motor vehicle accidents (16 cases), animal attacks (all from dogs; 5 cases) and malicious acts (1 case). Emaciation resulting in death was attributed to senescence (9), sarcoptic mange (7), starvation (6) and dental disease (6). Sarcoptic mange caused mortality, with or without emaciation, in 16 cases. There was one case each of congenital abdominal hernia, cardiomyopathy, burns and ivermectin toxicosis, and two of oxalate nephropathy. Neoplasms were the cause of mortality in 12 koalas and included five female reproductive tract neoplasms and, importantly, only two lymphomas, in contrast with previous studies in which lymphoma is the most prevalent neoplasm.

Conclusion: This is the most comprehensive data analysis of mortality amongst Victorian koalas, and one of the few autopsy studies on koalas. Infectious disease including presumptive chlamydiosis, emaciation and trauma were the leading causes of mortality amongst koalas submitted for autopsy at this institution.

Antimicrobial resistance (AMR) is a global health threat for people and animals, including wildlife. The overuse and misuse of antimicrobials continues to fuel the spread of AMR. We performed a retrospective analysis of systemic antibiotic administration in fire-affected koalas admitted to two wildlife treatment facilities during the catastrophic Australian wildfires in 2019-2020, to assess the practice of antimicrobial stewardship during a wildlife emergency. Triage and treatment records were obtained for fire-affected koalas (n = 355) admitted to two facilities during the wildfires. Analyses showed that 40.3% of koalas at Facility A and 35.0% of koalas at Facility B received systemic antibiotics. The majority of antibiotics (63.9%, comprising multiple types of beta-lactams) administered to koalas at Facility A were prophylactic treatments in koalas with noninfected moderate to severe cutaneous burn wounds. The majority of antibiotics (75.0%, comprising chloramphenicol and enrofloxacin) administered to koalas at Facility B were chlamydial disease treatments. Overall, 29.4% of all antibiotic treatments (predominantly beta-lactams and enrofloxacin) were administered for recorded clinical infections. Where koala-specific guidelines and protocols for treating burn wounds were not available, there was an overuse of systemic antibiotics and frequently sub-optimal antibiotic stewardship in burnt koalas during the 2019-2020 wildfire emergency response. Best practice antibiotic prescribing was also not always feasible due to a shortage of first-choice antibiotics (e.g., injectable chloramphenicol for chlamydial disease). This study highlights the importance of preparedness for future wildfire events and identifies a need for equipping veterinarians with guidelines for treating fire-affected koalas during emergency situations. Additional education, guidance and resources are required to enable appropriate antimicrobial stewardship by responding veterinarians during wildlife emergencies.

Nearly all cases of cryptococcosis in koalas are caused by Cryptococcus gattii species complex. A rare case of meningitis due to Cryptococcus neoformans VNI/AFLP1 (abbreviated VNI) is described in a koala with nasal colonisation by both species complexes. An eight-year-old koala in a wildlife park presented for seizures and returned a positive latex cryptococcal antigen agglutination test. The koala was euthanased due to the severity of disease, and a post-mortem computed tomography study showed mild mucosal thickening of the right nasal turbinates. The necropsy also showed slightly turbid cisternal cerebrospinal fluid and meningeal opacity. Histology revealed severe granulomatous cryptococcal meningitis and paucireactive right cryptococcal rhinitis. Fungal cultures yielded heavy pure growths of C. neoformans from the brain and spinal cord, and comparable heavy growths of both C. neoformans and C. gattii from the nasal cavity. Cryptococcus species complexes were identified by mass spectrometry (MALDI-TOF) and multi-locus sequence typing (MLST). The C. neoformans isolates from the brain, spinal cord and nasal cavity were identical by MLST and classified as sequencing type (ST) 23 and molecular type (MT) VNI. The C. gattii isolates were classified as ST 51 and AFLP4/VGI (abbreviated VGI). This suggests that the meningitis developed as an extension of C. neoformans VNI from nasal cavity colonisation. This is the second documented case of central nervous system (CNS) cryptococcosis due to C. neoformans species complex in a koala and the first in Australia. Despite heavy nasal colonisation by C. gattii, only the C. neoformans isolate progressed to meningitis.