Melbourne Veterinary School - Research Publications
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ItemEstablishing haematological and biochemical reference intervals for free-ranging Scottish golden eagle nestlings (Aquila chrysaetos)(SPRINGER, 2022-06-01)Abstract Health assessment of individuals is an important aspect of monitoring endangered wildlife populations. Haematological and biochemical values are a common health assessment tool, and whilst reference values are well established for domestic species, they are often not available for wild animal species. This study established 31 haematological and biochemical reference intervals for golden eagle (Aquila chrysaetos) nestlings in Scotland, in order to improve the understanding of the species’ health and support conservation efforts. Reference intervals were created from 47 nestlings (ages 2–7.5 weeks old) across 37 nests, to date, the largest sample of wild individuals of this species and age cohort sampled for these purposes. Upper reference intervals for concentrations of lymphocytes, total protein, cholesterol, triglycerides, uric acid, and monocytes, calculated in this study, are higher than those found for adult raptors and the interval span is higher than that observed in adult raptors for concentrations of AST, albumin, eosinophil, LDH, and monocyte count. Statistically significant positive correlations were found with age and concentrations of haemoglobin, lymphocytes, serum pH, and creatine kinase, and significant negative correlations with age for concentrations of thrombocytes, heterophils, total protein, globulin, and lactate dehydrogenase. Packed cell volume was significantly higher for females than males, and concentration of calcium and eosinophils were higher for individuals in good body condition than those in moderate body condition. The reference intervals produced by this study will be of important use to the veterinary and conservation management communities and will aid the long-term monitoring of the Scottish golden eagle population health.
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ItemSeroprevalence of Toxoplasma gondii in burrowing bettongs (Bettongia lesueur): A comparison of cat-free and cat-exposed populations(CSIRO Publishing, 2022-01-01)Toxoplasma gondii is a ubiquitous protozoan transmitted by felids and infection, morbidity, and mortality occur in numerous marsupial species. This study explores the relationship between cat exposure and Toxoplasma in burrowing bettongs (Bettongia lesueur) in the Arid Recovery Reserve (ARR), South Australia. We estimated seroprevalence, using a modified agglutination test for T. gondii-specific immunoglobulins, in cat-free and cat-exposed bettong populations. Tissue samples collected opportunistically from bettong carcasses and from cats within and around the reserve were screened for T. gondii DNA using multiplex real-time polymerase chain reaction (M-qPCR). Two cats trapped inside the ARR tested positive (50.0%; 95% CI: 15.0-85.0%). All bettongs tested from the cat-free (n = 48) and cat-exposed (n = 19) exclosures were seronegative (95% CI: 0-7.41% and 0-16.82% respectively). We found no evidence of fatal toxoplasmosis, with all bettong carcasses negative on M-qPCR (n = 11). We propose that T. gondii was not detected in bettongs coexisting with cats primarily due to low exposure of bettongs at the time of sampling, possibly due to poor oocyst viability in arid conditions or low shedding by cats. Ongoing screening throughout high and low rainfall years should be conducted to better establish the risk of Toxoplasma to bettongs in the ARR.
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ItemThe genome sequence of the European golden eagle, Aquila chrysaetos chrysaetos Linnaeus 1758.(F1000 Research Ltd, 2021)We present a genome assembly from an individual female Aquila chrysaetos chrysaetos (the European golden eagle; Chordata; Aves; Accipitridae). The genome sequence is 1.23 gigabases in span. The majority of the assembly is scaffolded into 28 chromosomal pseudomolecules, including the W and Z sex chromosomes.
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ItemOne Health in Indigenous Communities: A Critical Review of the Evidence(MDPI, 2021-11-01)Indigenous populations around the world face disproportionately high rates of disease related to the environment and animals. One Health is a concept that has been used effectively to understand and address these health risks. One Health refers to the relationships and interdependencies between animal, human, and environmental health and is an emerging research field that aligns with indigenous views of health. To understand the applicability of One Health in indigenous communities, a critical review was undertaken to investigate evidence of One Health research in indigenous communities internationally, assess the strength of evidence, and understand what gaps are present. This review included the appraisal of twenty-four studies based in five regions: Canada, Africa, Australia, South America, and Central America. The review found that there is a need for studies of high strength, with rigorous methods, local leadership, and active involvement of indigenous viewpoints, to be undertaken in indigenous communities internationally that focus on One Health. It highlights the need to further consider indigenous viewpoints in research to reduce limitations, increase effectiveness of findings, consider appropriateness of recommendations, and benefit communities.
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ItemImpact of diet on faecal output and caecotroph consumption in rabbits(WILEY, 2017-01-01)OBJECTIVES: To assess the impact of four rabbit diets (hay only, extruded diet with hay, muesli with hay and muesli only) on faecal pellet size, faecal output and caecotrophy. MATERIALS AND METHODS: Thirty-two Dutch rabbits were studied over 17 months. Faecal pellet size and weight were measured in weeks 3, 9, 21 and 43 and faecal output in weeks 10, 22 and 45. Number of uneaten caecotrophs was recorded weekly. RESULTS: Faecal pellets were consistently smaller and lighter in rabbits fed muesli only, and the size of pellets produced by those fed muesli with hay decreased over the course of the study. Faecal output was greatest in rabbits with the highest hay intake. Uneaten caecotrophs were found in greatest frequency in rabbits fed muesli. CLINICAL SIGNIFICANCE: Muesli diets have a negative effect on faecal output and caecotroph ingestion and may therefore predispose to digestive disorders. Higher hay intake is associated with greater faecal output and fewer uneaten caecotrophs and may assist in preventing the gastrointestinal stasis.
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ItemGeographical Distribution and Genetic Diversity of Bank Vole Hepaciviruses in Europe(MDPI, 2021-07-01)The development of new diagnostic methods resulted in the discovery of novel hepaciviruses in wild populations of the bank vole (Myodes glareolus, syn. Clethrionomys glareolus). The naturally infected voles demonstrate signs of hepatitis similar to those induced by hepatitis C virus (HCV) in humans. The aim of the present research was to investigate the geographical distribution of bank vole-associated hepaciviruses (BvHVs) and their genetic diversity in Europe. Real-time reverse transcription polymerase chain reaction (RT-qPCR) screening revealed BvHV RNA in 442 out of 1838 (24.0%) bank voles from nine European countries and in one of seven northern red-backed voles (Myodes rutilus, syn. Clethrionomys rutilus). BvHV RNA was not found in any other small mammal species (n = 23) tested here. Phylogenetic and isolation-by-distance analyses confirmed the occurrence of both BvHV species (Hepacivirus F and Hepacivirus J) and their sympatric occurrence at several trapping sites in two countries. The broad geographical distribution of BvHVs across Europe was associated with their presence in bank voles of different evolutionary lineages. The extensive geographical distribution and high levels of genetic diversity of BvHVs, as well as the high population fluctuations of bank voles and occasional commensalism in some parts of Europe warrant future studies on the zoonotic potential of BvHVs.
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ItemWildlife conservation in a fragmented landscape: the Eurasian red squirrel on the Isle of Wight(SPRINGER, 2021-06-05)Abstract Island populations may have a higher extinction risk due to reduced genetic diversity and need to be managed effectively in order to reduce the risk of biodiversity loss. The Eurasian red squirrels (Sciurus vulgaris) in the south of England only survive on three islands (the Isle of Wight, Brownsea and Furzey islands), with the Isle of Wight harbouring the largest population in the region. Fourteen microsatellites were used to determine the genetic structure of red squirrel populations on the Isle of Wight, as well as their relatedness to other populations of the species. Our results demonstrated that squirrels on these islands were less genetically diverse than those in Continental mainland populations, as would be expected. It also confirmed previous results from mitochondrial DNA which indicated that the squirrels on the Isle of Wight were relatively closely related to Brownsea island squirrels in the south of England. Importantly, our findings showed that genetic mixing between squirrels in the east and west of the Isle of Wight was very limited. Given the potential deleterious effects of small population size on genetic health, landscape management to encourage dispersal of squirrels between these populations should be a priority.
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ItemFatal exudative dermatitis in island populations of red squirrels (Sciurus vulgaris): spillover of a virulent Staphylococcus aureus clone (ST49) from reservoir hosts.(Microbiology Society, 2021-05)Fatal exudative dermatitis (FED) is a significant cause of death of red squirrels (Sciurus vulgaris) on the island of Jersey in the Channel Islands where it is associated with a virulent clone of Staphylococcus aureus, ST49. S. aureus ST49 has been found in other hosts such as small mammals, pigs and humans, but the dynamics of carriage and disease of this clone, or any other lineage in red squirrels, is currently unknown. We used whole-genome sequencing to characterize 228 isolates from healthy red squirrels on Jersey, the Isle of Arran (Scotland) and Brownsea Island (England), from red squirrels showing signs of FED on Jersey and the Isle of Wight (England) and a small number of isolates from other hosts. S. aureus was frequently carried by red squirrels on the Isle of Arran with strains typically associated with small ruminants predominating. For the Brownsea carriage, S. aureus was less frequent and involved strains associated with birds, small ruminants and humans, while for the Jersey carriage S. aureus was rare but ST49 predominated in diseased squirrels. By combining our data with publicly available sequences, we show that the S. aureus carriage in red squirrels largely reflects frequent but facile acquisitions of strains carried by other hosts sharing their habitat ('spillover'), possibly including, in the case of ST188, humans. Genome-wide association analysis of the ruminant lineage ST133 revealed variants in a small number of mostly bacterial-cell-membrane-associated genes that were statistically associated with squirrel isolates from the Isle of Arran, raising the possibility of specific adaptation to red squirrels in this lineage. In contrast there is little evidence that ST49 is a common carriage isolate of red squirrels and infection from reservoir hosts such as bank voles or rats, is likely to be driving the emergence of FED in red squirrels.
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ItemBacterial Pathogens and Symbionts Harboured by Ixodes ricinus Ticks Parasitising Red Squirrels in the United Kingdom(MDPI, 2021-04-01)Red squirrels (Sciurus vulgaris) are native to most of Eurasia; in much of the United Kingdom, they have been supplanted by the non-native grey squirrel, and are considered an endangered species. Very little is known about the range of tick-borne pathogens to which UK red squirrels are exposed. As part of trap-and-release surveys examining prevalence of Mycobacterium spp. in red squirrel populations on two UK islands, Ixodes ricinus ticks were removed from squirrels and PCR screened for Borrelia spp., intracellular arthropod-borne bacteria and the parasitic wasp Ixodiphagus hookeri. At both sites, the most commonly encountered tick-transmitted bacterium was Borrelia burgdorferi sensu lato (overall minimum prevalence 12.7%), followed by Anaplasma phagocytophilum (overall minimum prevalence 1.6%). Single ticks infected with Spiroplasma were found at both sites, and single ticks infected with Borrelia miyamotoi or an Ehrlichia sp. at one site. Ticks harbouring Wolbachia (overall minimum prevalence 15.2%) were all positive for I. hookeri. Our study shows that UK red squirrels are potentially exposed to a variety of bacterial pathogens via feeding ticks. The effects on the health and survival of this already vulnerable wildlife species are unknown, and further studies are needed to evaluate the threat posed to red squirrels by Borrelia and other tick-borne pathogens.
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ItemInfectious disease and emergency conservation interventions(WILEY, 2020-07-22)