Australian Veterinary Journal最新文献

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.

A progressive tremorgenic syndrome characterised by ataxia and head nodding is well documented in sheep and cattle affected by chronic Phalaris toxicosis (CPT), and is increasingly documented in the eastern grey kangaroo {(EGK), Macropus giganteus} in southeastern Australia. It is characterised on gross necropsy by areas of acquired localised pigment deposits within the brain. This pigment was previously considered a storage disease, but more recently has been determined to be a metabolic breakdown product of tryptamine alkaloids within Phalaris species (spp) of introduced grasses. The study included 61 EGKs that were euthanased after a diagnosis of clinically advanced CPT, histopathological studies were performed on all cases and transmission electron microscopic studies on six brains. Histological examination of the brains from EGKs revealed brown pigmentation of neurons, particularly of large motor neurons, with accumulations of discrete granules in the cytoplasm that stained positive with stains used to identify melanin. This feature and the characteristic ultrastructural appearance of the pigment granules leaves little doubt that the pigment is primarily melanin in nature. Specifically, ultrastructural detail of the granules was consistent with neuromelanin present in the brains of higher order primates and humans and has been associated with susceptibility to neurodegenerative diseases in man including Parkinson's disease. Given greater urbanisation and reduced access to native pasture a greater understanding of pathogenesis of CPT is of major importance not only for kangaroo welfare but potentially as a model for neurodegenerative diseases in humans.

Introduction: Physiological responses to anaesthesia are described for the first time in eastern barred bandicoot (EBB; Perameles gunnii) and southern brown bandicoot (SBB; Isoodon obesulus).

Method: Two hundred and six field anaesthetics were carried out on free-ranging bandicoots (82 EBB and 66 SBB) in North West Tasmania. Animals were induced and maintained under general anaesthesia using isoflurane administered via a face mask.

Results: On average, animals required 3% isoflurane for anaesthesia maintenance and recovered within 2-3 min of isoflurane being discontinued. SBB had higher respiratory rates than EBB. Otherwise, we found no significant differences in anaesthetic parameters between the bandicoot species, between sexes or for females with pouch young. Hypothermia was the only anaesthetic-associated adverse event during this study, occurring in 26 anaesthetics (12.6%). At the start of anaesthesia, bandicoots had a mean body temperature of 35.0°C (SEM 0.8, SD 1.2), and 95% of animals lost temperature during anaesthesia. Bandicoots with an initial body temperature of less than 34.5°C had 20 times greater risk (odds ratio 20.52, 95% CI 5.58-77.19) of developing hypothermia (defined as T_b < 33°C). Heart rates ranged from 100 to >300 beats per minute, and respiratory rates ranged from 8 to 64 breaths per minute. Data support a heart rate reference interval of 140-285 (mean 208, SD 42.72) and a respiratory rate interval of 10-34 for SBB (mean 21, SD 8.89) and 8-20 for EBB (mean 12, SD 4.72) during maintenance of inhalant anaesthesia.

Conclusions: With hypothermia the only anaesthesia-related adverse event during this study, results support the safety of this form of chemical restraint in the field and provide empirical data that may be used to guide anaesthesia for bandicoots. Results suggest that standard inhalational anaesthetic protocols are suitable for bandicoots irrespective of weight, sex and reproductive status.

Australia's large populations of feral and extensively farmed livestock pose challenges to implementing response plans in the event of an Emergency Animal Disease outbreak. This study aimed to determine if a “Destroy and Let Lie” approach to carcass disposal (leaving carcasses in situ to decompose naturally after field euthanasia) would reliably inactivate Foot and Mouth Disease virus (FMDV) and African Swine Fever virus (ASFV) under Australian conditions. Ninety-five animals (24 each of cattle, sheep, goats and 23 pigs) were used across six trials, conducted in winter and summer, in three locations in Eastern Australia. After euthanasia, temperature and pH were measured at six internal anatomical sites hourly for 24 h, then less frequently for a further 24 h. Data were compared with published FMDV and ASFV inactivation thresholds to assess the likely effectiveness of field decomposition in reducing viral infectivity. Tissue pH levels generally declined for the first 6–12 h postmortem. Based on a pH threshold of <6, FMDV would be reliably inactivated in the thoracic and abdominal cavities and deep and superficial muscle sites. In contrast, no porcine tissues at any location in any season would provide inactivation of ASFV, based on a pH threshold of <3.9. “Destroy and Let Lie” appears to be a suitable approach to reduce risk of FMDV transmission from carcasses that cannot be disposed of using conventional means under Australian field conditions. This would not be the case for an ASF outbreak, where expected viral inactivation would be minimal.

Progressive feline leukaemia virus (FeLV) infection dramatically shortens the lives of infected cats, causing acquired immunodeficiency, aplastic anaemia, lymphoma, leukaemia and other myeloproliferative diseases. The potential impact of regressive FeLV infection on the development of disease remains largely unknown, although there is evidence it contributes to lymphoma development. Despite a perception that there has been a general decline in the incidence of progressive FeLV infection in Australia and New Zealand, it remains an important health threat and the risk of infection should not be ignored. Clinicians should therefore have a thorough understanding of the complexities surrounding the diagnosis, management and prevention of this disease. Point-of-care (PoC) antigen testing using whole blood is the first step to detect progressive FeLV infection. Clinicians should remember the increased rate of false-positive results using such kits when the disease being detected is at a low prevalence. We therefore advise that confirmatory FeLV polymerase chain reaction (PCR) testing to detect proviral DNA is essential before a PoC-positive cat can be confirmed as being FeLV-infected. Critically, progressively infected cats should not be euthanased because of a positive FeLV diagnosis, as some cats will remain healthy for many years. Regressively infected cats should not be used as blood donors, so blood donor programmes should include FeLV antigen and provirus PCR testing in their standard screening protocols. No cure currently exists for progressive or regressive FeLV infection; therefore, veterinarians should advocate to minimise the exposure of cats to FeLV as a first-line preventative strategy. The most reliable way to achieve this is for cats to be kept indoors, or with secured outdoor access (e.g., cat enclosures and secure gardens). Cats kept in this manner do not require FeLV vaccination. All animal holding facilities should aim to individually house untested adult cats to limit the spread of FeLV infection. For at-risk cats that cannot be kept indoors/enclosed, or for cats that live together with known FeLV-infected cats, vaccination should be undertaken. Two pentavalent vaccines containing inactivated whole-FeLV are currently available in Australia, whereas no FeLV vaccine is currently available in New Zealand. Given the unavailability of monovalent FeLV vaccines, we endorse the use of a pentavalent vaccine in Australia only in FeLV-endemic catteries or in situations where there is a demonstrable and substantial risk of FeLV exposure. Manufacturers are encouraged to reintroduce efficacious monovalent FeLV vaccines in Australia and New Zealand. Further research into potential antiretroviral therapy to treat FeLV infections in cats is needed.

Osteoarthritis (OA) is a prevalent and progressive degenerative joint disease in dogs, leading to chronic pain, reduced mobility, and diminished quality of life. Conventional management strategies primarily aim to alleviate and palliate clinical signs of pain and reduced mobility. Platelet-rich plasma (PRP) is an emerging regenerative therapy that has gained interest for its potential disease modifying effects, through modulating inflammation and promoting tissue repair. This paper provides a critical appraisal of current literature on the effectiveness of intra-articular injection of PRP compared to a placebo on the clinical outcomes of lameness and pain in dogs with OA. Findings from 7 studies indicate that current evidence supporting the effectiveness of PRP in reducing pain and lameness is weak. Further research in the form of large, randomised, blinded controlled clinical trials is required to further assess the efficacy of PRP.

A 9-year-old British Short Hair cat presented with a 12-month history of progressive exophthalmos to the right eye. A computed tomography (CT) scan was performed, and it revealed a large 3.1 × 2 × 2.3 cm peripherally contrast-enhancing right retrobulbar mass in the region of the zygomatic salivary gland. Preliminary results of a fine-needle aspirate (FNA) were inconclusive, so the mass was surgically excised via the right partial zygomatic ostectomy approach. Histopathological evaluation was consistent with benign ductal neoplasia of salivary gland origin.