Australian Horses Research Articles

Detection of Equine Parvovirus-Hepatitis Virus and Equine Hepacivirus in Archived Sera from Horses in France and Australia.

Reports of newly discovered equine hepatotropic flavi- and parvoviruses have emerged throughout the last decade in many countries, the discovery of which has stimulated a great deal of interest and clinical research. Although commonly detected in horses without signs of disease, equine parvovirus hepatitis (EqPV-H) and equine hepacivirus (EqHV) have been associated with liver disease, including following the administration of contaminated anti-toxin. Our aim was to determine whether EqPV-H and EqHV are present in Australian horses and whether EqPV-H was present in French horses and to examine sequence diversity between strains of both viruses amongst infected horses on either side of the globe. Sera from 188 Australian horses and 256 French horses from horses with and without clinical signs of disease were collected. Twelve out of 256 (4.7%) and 6 out of 188 (3.2%) French and Australian horses, respectively, were positive for the molecular detection of EqPV-H. Five out of 256 (1.9%) and 21 out of 188 (11.2%) French and Australian horses, respectively, were positive for the molecular detection of EqHV. Australian strains for both viruses were genomically clustered, in contrast to strains from French horses, which were more broadly distributed. The findings of this preliminary survey, with the molecular detection of EqHV and EqPV-H in Australia and the latter in France, adds to the growing body of awareness regarding these recently discovered hepatotropic viruses. It has provided valuable information not just in terms of geographic endemicity but will guide equine clinicians, carers, and authorities regarding infectious agents and potential impacts of allogenic tissue contamination. Although we have filled many gaps in the world map regarding equine hepatotropic viruses, further prospective studies in this emerging field may be useful in terms of elucidating risk factors and pathogenesis of these pathogens and management of cases in terms of prevention and diagnosis.

Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding

This study reports the spatial and temporal distribution of ascarid and strongylid nematodes in Thoroughbred horses by age category across different climatic zones in Australia over an 18-month period. Faecal samples (n = 2046) from individual horses were analysed using the modified McMaster technique for faecal egg counts (FECs). Strongylids were identified using PCR-directed next-generation sequencing of the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA. Yearlings had the highest prevalence (82%) of strongyle eggs followed by weanlings (79%), foals (58%), wet mares (49%) and dry mares (46%). For Parascaris spp., foals had the highest prevalence (35%) followed by weanlings (21%) and yearlings (10%). The highest mean FECs for Parascaris spp. were observed in foals (525 eggs per gram [EPG] of faeces) while those for strongyles were in yearlings (962 EPG). Among horses that were classified as adults at the time of sampling, 77% (860 of 1119) of mares were low (i.e., <250 EPG) strongyle egg-shedders. Mean strongyle FEC counts were highest in the Mediterranean (818 EPG) followed by summer (599 EPG), winter (442 EPG), and non-seasonal (413 EPG) rainfall zones. Twenty-six nematode species were detected, with Cylicostephanus longibursatus (26.5%), Cylicocyclus nassatus (23.7%) and Coronocyclus coronatus (20.5%) being the most frequently detected species. Their richness and relative abundance varied with horse age, season and climatic zone. In addition, Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus) were also detected. This comprehensive study elucidates spatial (climatic zone) and temporal (i.e., seasonal) trends in prevalence and burdens of intestinal nematodes in Australian horses using non-invasive conventional and molecular methods. The information presented in this study is crucial for developing integrated management strategies to control horse parasites in farmed horses.

A national survey of anthelmintic resistance in ascarid and strongylid nematodes in Australian Thoroughbred horses

This study quantified the extent of anthelmintic resistance (AR) in ascarid and strongylid nematodes against commonly used anthelmintics in Australian Thoroughbred horses. Faecal egg count reduction tests (FECRTs, n = 86) and egg reappearance period (ERP) tests were conducted on 22 farms across Australia. Faecal egg counts (FECs) were determined using the modified McMaster technique, and percent faecal egg count reduction (%FECR) was calculated using the Bayesian hierarchical model and hybrid Frequentist/Bayesian analysis method. The results were interpreted using old (published in 1992) and new (2023) research guidelines of the World Association for the Advancement of Veterinary Parasitology (WAAVP). The species composition of strongylid nematodes was detected utilising a DNA-metabarcoding method using pre- and post-treatment samples. Resistance was observed in strongylid nematodes to commonly used single-active and combination anthelmintics, including ivermectin (IVM %FECR range: 82%–92%; 95% lower credible interval (LCI) range: 80%–90%), abamectin (ABM: 73%–92%; 65%–88%), moxidectin (MOX: 89%–91%; 84%–89%), oxfendazole (OFZ: 0%–56%; 0%–31%) and its combination with pyrantel (OFZ + PYR: 0%–82%; 0%–78%). Resistance in Parascaris spp. was observed to IVM (10%–43%; 0%–36%), ABM (0%; 0%) and MOX (0%; 0%). When the new thresholds recommended by the WAAVP were used, AR was detected in six additional FECRTs for strongylids and three more tests for Parascaris spp., introducing resistance to OFZ and OFZ + PYR in the latter. Shortened ERPs (4–6 weeks) of strongylids were observed in 31 FECRTs in which AR was not detected at 2 weeks post-treatment for all the anthelmintics tested. Among cyathostomins, Cylicocyclus nassatus, Cylicostephanus longibursatus and Coronocyclus coronatus were the most prevalent species at 2 weeks post-treatment, whereas the main species appearing at five weeks following treatments with macrocyclic lactones were Cylicocyclus nassatus, Cylicostephanus longibursatus and Cylicocyclus ashworthi. After treatment with OFZ + PYR, the latter three, plus Coronocyclus coronatus and Cyathostomum catinatum, were detected at 5 weeks post-treatment. Overall, the study highlights the prevalence of AR in both ascarids and strongylid nematodes against commonly used anthelmintic products to control worms in Australian horses. The results indicate that ML combination products provided acceptable efficacy at 2 weeks. However, ERP calculations suggest that products work less effectively than previously measured. It is suggested to regularly monitor the efficacy of the anthelmintics and consider changing the worm control practices to better manage worms and AR in Australian horses.

Assessment of worm control practices recommended by equine veterinarians in Australia.

This study aimed to assess Australian veterinarians' knowledge, perceptions and treatment strategies for worm control in horses with an online questionnaire. The questionnaire comprised 64 questions covering various aspects of: (i) veterinary practice; (ii) the veterinarian's knowledge of gastrointestinal nematodes (GINs) and the importance of parasites in different age groups of horses; (iii) the diagnosis and control of worms; (iv) anthelmintics and anthelmintic resistance (AR); (v) grazing management; and (vi) the means of communication and the discussion between veterinarians and their clients regarding worm control. Following a pilot survey, a link for the questionnaire survey was sent to all (n = 1,148) registered members of Equine Veterinarians Australia in April 2020. The response rate for the questionnaire was 10% (118 of 1,148). The findings of this study illustrate veterinarians' good understanding of aspects of equine parasites, including control. However, respondents mainly recommended frequent, interval-based prophylactic deworming in young horses, and only 40% (96 of 239) diagnosed GIN infections based on faecal egg count (FEC) results in all age groups of horses. Furthermore, only 27% (88 of 330) of the respondents made deworming decisions based on FECs. Most of the respondents recommended macrocyclic lactones (MLs) for all age groups of horses (71%, 481 of 677), and the most frequently used method to calculate the dose of anthelmintics was by estimating the weight of animals visually (53%, 63 of 118). Although the majority of respondents (97%, 115 of 118) perceived AR to be a critical issue in managing worms in horses, 58% (67 of 118) of them were unaware of the status of AR on their clients' properties. Forty-two percent (50 of 118) of the respondents perceived the presence of AR in worms, including pinworms (16%), strongylins (15%), species of Draschia and Habronema (6%), Strongyloides westeri (2%) and tapeworms (1%). Twenty-seven percent (32 of 118) of the respondents rarely discussed equine worm control practices with their clients. This study provides insights into the perception and worm control practices recommended by Australian veterinarians to manage equine parasites. The findings highlight the importance of continued education and awareness of AR, and the use of non-chemical methods as well as consideration of the legislation of prescription-only use of anthelmintics based on FECs to achieve sustainable control of GINs in Australian horses.

Genomic Analysis of Clostridioides difficile Recovered from Horses in Western Australia.

Clostridioides difficile poses an ongoing threat as a cause of gastrointestinal disease in humans and animals. Traditionally considered a human healthcare-related disease, increases in community-associated C. difficile infection (CDI) and growing evidence of inter-species transmission suggest a wider perspective is required for CDI control. In horses, C. difficile is a major cause of diarrhoea and life-threatening colitis. This study aimed to better understand the epidemiology of CDI in Australian horses and provide insights into the relationships between horse, human and environmental strains. A total of 752 faecal samples from 387 Western Australian horses were collected. C. difficile was isolated from 104 (30.9%) horses without gastrointestinal signs and 19 (37.8%) with gastrointestinal signs. Of these, 68 (55.3%) harboured one or more toxigenic strains, including C. difficile PCR ribotypes (RTs) 012 (n = 14), 014/020 (n = 10) and 087 (n = 7), all prominent in human infection. Whole-genome analysis of 45 strains identified a phylogenetic cluster of 10 closely related C. difficile RT 012 strains of equine, human and environmental origin (0-62 SNP differences; average 23), indicating recent shared ancestry. Evidence of possible clonal inter-species transmission or common-source exposure was identified for a subgroup of three horse and one human isolates, highlighting the need for a One Health approach to C. difficile surveillance.

Investigating the Market Value of Brumbies (Equus caballus) in the Australian Riding Horse Market.

Feral horses, also known as brumbies, are widely distributed across Australia with some populations being managed largely by human intervention. Rehoming of suitable feral horses following passive trapping has wide community acceptance as a management tool. However, there is little information about the number and relative economic value of feral horses compared with cohorts in the riding horse market. We examined 15,404 advertisements of horses for sale in 53 editions of Horse Deals, published from February 2017 to July 2022. Despite the considerable media attention and public scrutiny surrounding feral horse management, rehomed feral horses represented only a tiny fraction of the horse market in the current study. Of the 15,404 advertisements examined, only 128 (0.0083%) were for feral horses. We recorded phrases used to describe behavioural characteristics and other variables. The following variables were found to be not independent: Ridden Status, Height, Age, Sex, Colour, and Warning terms/more work. Using descriptive statistics to describe basic features of the data, the average price for feral horses ($1408) was lower than that for domestic horses ($1790) with the maximum price for a domestic horse being nearly twice the maximum for a feral horse. Univariate analysis showed feral horses were over-represented among "Unbroken" horses and underrepresented among "Ridden", "Broodmare" and "Harness" horses compared with domestic bred horses (p < 0.001). Feral horses appeared over-represented at shorter heights, among younger age groups (3 years or younger and 3.1 to 6 years) (p < 0.001) and in the dilute colour category (p = 0.008). The multivariable mixed model on price revealed that for domestic horses, the highest estimated marginal mean price averaged across the colour categories was for ridden horses aged 6.1-10-year-old at $1657.04 (95% CI $1320.56-$2074.66). In contrast, for feral horses, the multivariable mixed model demonstrated the similar highest estimated marginal mean averaged was for green broken 3-6-year-old horses that have undergone foundation training under saddle at $2526.97 (95% CI $1505.63-$4208.27). Australian feral horses were valued differently tfromsimilar domestic horses in the recreational riding horse market and further research is warranted to determine appropriate target markets and boost the sustainability of rehoming as a feral horse management tool.

A survey on the use of rugs in Australian horses.

The practice of horse rugging has important implications for horse welfare and performance, but in Australia, rugging practices have not been properly documented. The objective of this study was to obtain an understanding of Australian horse rugging practices. An online survey reviewed the management of 2659 Australian horses over 12 months. Of the reported horses a total of 84.8% were rugged, although most owners (69.5%) indicated that they were unsure whether horses needed to be rugged at all. Rugging was felt by 59.8% of owners to be a requirement for horses in competition. Riding and competition were significantly associated with the use of rugs. Nearly all respondents (89.0%) felt that 'over-rugging' was a concern. However, 4.8% of owners would use up to 4 rugs at any one time on their horse and 21.4% of horses were still rugged in temperatures above 20°C in Australia. Many Australian horse owners (42.8%) also believe that horses feel cold if they are not rugged. Anthropomorphism when it comes to rugging horses cannot be justified as the horse has a much wider thermoneutral zone (TNZ) than humans. Australian climate, owner opinions, equestrian discipline and whether a horse is used for riding influence Australian horse rugging practices. However, current practices are based on limited available research and are not necessarily to the benefit of the horse. The major limitation was that the survey likely attracted respondents who are interested in the topic creating a self-selection bias.

Assessment of Humoral and Long-Term Cell-Mediated Immune Responses to Recombinant Canarypox-Vectored Equine Influenza Virus Vaccination in Horses Using Conventional and Accelerated Regimens Respectively.

During Australia’s first and only outbreak of equine influenza (EI), which was restricted to two northeastern states, horses were strategically vaccinated with a recombinant canarypox-vectored vaccine (rCP-EIV; ProteqFlu™, Merial P/L). The vaccine encoded for haemagglutinin (HA) belonging to two equine influenza viruses (EIVs), including an American and Eurasian lineage subtype that predated the EIV responsible for the outbreak (A/equine/Sydney/07). Racehorses in Victoria (a southern state that remained free of EI) were vaccinated prophylactically. Although the vaccine encoded for (HA) belonged to two EIVs of distinct strains of the field virus, clinical protection was reported in vaccinated horses. Our aim is to assess the extent of humoral immunity in one group of vaccinated horses and interferon-gamma ((EIV)-IFN-γ)) production in the peripheral blood mononuclear cells (PBMCs) of a second population of vaccinated horses. Twelve racehorses at work were monitored for haemagglutination inhibition antibodies to three antigenically distinct equine influenza viruses (EIVs) The EIV antigens included two H3N8 subtypes: A/equine/Sydney/07) A/equine/Newmarket/95 (a European lineage strain) and an H7N7 subtype (A/equine/Prague1956). Cell-mediated immune responses of: seven racehorses following an accelerated vaccination schedule, two horses vaccinated using a conventional regimen, and six unvaccinated horses were evaluated by determining (EIV)-IFN-γ levels. Antibody responses following vaccination with ProteqFlu™ were cross-reactive in nature, with responses to both H3N8 EIV strains. Although (EIV)IFN-γ was clearly detected following the in vitro re-stimulation of PBMC, there was no significant difference between the different groups of horses. Results of this study support reports of clinical protection of Australian horses following vaccination with Proteq-Flu™ with objective evidence of humoral cross-reactivity to the outbreak viral strain A/equine/Sydney/07.

Serological Hendra Virus Diagnostics Using an Indirect ELISA-Based DIVA Approach with Recombinant Hendra G and N Proteins.

Since the identification of Hendra virus (HeV) infections in horses in Australia in 1994, more than 80 outbreaks in horses have been reported, and four out of seven spillover infections in humans had a fatal outcome. With the availability of a subunit vaccine based on the HeV-Glycoprotein (HeV-G), there is a need to serologically Differentiate the Infected from the Vaccinated Animals (DIVA). We developed an indirect ELISA using HeV-G expressed in Leishmania tarentolae and HeV-Nucleoprotein (HeV-N) expressed in recombinant baculovirus-infected insect cells as antigens. During evaluation, we tested panels of sera from naïve, vaccinated and infected horses that either originated from a Hendra-virus free region, or had been pre-tested in validated diagnostic tests. Our data confirm the reliability of this approach, as HeV-N-specific antibodies were only detected in sera from infected horses, while HeV-G-specific antibodies were detected in infected and vaccinated horses with a high level of specificity and sensitivity. Given the excellent correlation of data obtained for German and Australian HeV-negative horses, we assume that this test can be applied for the testing of horse serum samples from a variety of geographical regions.

Identification of W13 in the American Miniature Horse and Shetland Pony Populations.

Coat color is a trait of economic significance in horses. Variants in seven genes have been documented to cause white patterning in horses. Of the 34 variants that have been identified in KIT proto-oncogene, receptor tyrosine kinase (KIT), 27 have only been reported in a single individual or family and thus not all are routinely offered for genetic testing. Therefore, to enable proper use of marker-assisted selection, determining breed specificity for these alleles is warranted. Screening 19 unregistered all-white Shetland ponies for 16 white patterning markers identified 14 individuals whose phenotype could not be explained by testing results. In evaluating other known dominant white variants, 14 horses were heterozygous for W13. W13 was previously only reported in two quarter horses and a family of Australian miniature horses. Genotyping known white spotting variants in 30 owner-reported white animals (25 Miniature Horses and five Shetland ponies) identified two additional W13/N American Miniature Horses. The estimated allele frequency of W13 in the American Miniature Horse was 0.0063 (79 N/N, 1 W13/N) and the allele was not detected in a random sample (n = 59) of Shetland ponies. No homozygous W13 individuals were identified and W13/N ponies had a similar all-white coat with pink skin phenotype, regardless of the other white spotting variants present, demonstrating that W13 results in a Mendelian inherited dominant white phenotype and homozygosity is likely lethal. These findings document the presence of W13 in the American Miniature Horse and Shetland pony populations at a low frequency and illustrate the importance of testing for this variant in additional breeds.

Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

BackgroundCyathostomins are the most important and common parasitic nematodes of horses, with > 50 species known to occur worldwide. The frequent and indiscriminate use of anthelmintics has resulted in the development of anthelmintic resistance (AR) in horse nematodes. In this study we assessed the efficacy of commonly used anthelmintics against cyathostomins in Australian thoroughbred horses.MethodsTwo drug efficacy trials per farm were conducted on two thoroughbred horse farms in the state of Victoria, Australia. In the first trial, the horses on Farm A were treated with single and combinations of anthelmintics, including oxfendazole (OFZ), abamectin (ABM), abamectin and morantel (ABM + MOR), moxidectin (MOX) and oxfendazole and pyrantel (OFZ + PYR), at the recommended doses, whereas the horses on Farm B only received MOX, at the recommended dose. The faecal egg count reduction test (FECRT) was used to determine the efficacy and egg reappearance period (ERP) of anthelmintics. Based on the results of the first trial, the efficacies of MOX and a combination of ABM + MOR were reassessed to confirm their activities against cyathostomins.ResultsOf the five anthelmintic products tested on Farm A, resistance against OFZ, ABM and OFZ + PYR was found, with efficacies of − 41% (− 195% lower confidence limit [LCL]), 73% (60% LCL) and 82% (66% LCL) at 2 weeks post-treatment, respectively. The FECRT showed high efficacies of MOX and ABM + MOR (100%) at 2 week post-treatment and shortened ERPs for these anthelmintics (ABM + MOR: 4 weeks; MOX: 5 weeks). Resistance to MOX was found on Farm B, with a reduced efficacy of 90% (70% LCL) and 89% (82% LCL) at 2 weeks post-treatment in trials one and two, respectively.ConclusionsThis study provides the first evidence of MOX- and multidrug-resistant (ABM and combinations of anthelmintics) cyathostomins in Australia and indicates the need for continuous surveillance of the efficacy of currently effective anthelmintics and large-scale investigations to assess the ERP for various anthelmintics.Graphical

Association of Equine Herpesvirus 5 with Mild Respiratory Disease in a Survey of EHV1, -2, -4 and -5 in 407 Australian Horses.

Equine herpesviruses (EHVs) are common respiratory pathogens in horses; whilst the alphaherpesviruses are better understood, the clinical importance of the gammaherpesviruses remains undetermined. This study aimed to determine the prevalence of, and any association between, equine respiratory herpesviruses EHV1, -2, -4 and -5 infection in horses with and without clinical signs of respiratory disease. Nasal swabs were collected from 407 horses in Victoria and included clinically normal horses that had been screened for regulatory purposes. Samples were collected from horses during Australia's equine influenza outbreak in 2007; however, horses in Victoria required testing for proof of freedom from EIV. All horses tested in Victoria were negative for EIV, hence archived swabs were available to screen for other pathogens such as EHVs. Quantitative PCR techniques were used to detect EHVs. Of the 407 horses sampled, 249 (61%) were clinically normal, 120 (29%) presented with clinical signs consistent with mild respiratory disease and 38 (9%) horses had an unknown clinical history. Of the three horses detected shedding EHV1, and the five shedding EHV4, only one was noted to have clinical signs referable to respiratory disease. The proportion of EHV5-infected horses in the diseased group (85/120, 70.8%) was significantly greater than those not showing signs of disease (137/249, 55%). The odds of EHV5-positive horses demonstrating clinical signs of respiratory disease were twice that of EHV5-negative horses (OR 1.98, 95% CI 1.25 to 3.16). No quantitative difference between mean loads of EHV shedding between diseased and non-diseased horses was detected. The clinical significance of respiratory gammaherpesvirus infections in horses remains to be determined; however, this survey adds to the mounting body of evidence associating EHV5 with equine respiratory disease.

Pre-race and race management impacts serum muscle enzyme activity in Australian endurance horses.

BackgroundMarked increases in serum muscle enzyme activity can occur in endurance horses but the diagnostic certainty in predicting cases of myopathy is unclear. Improved understanding of horse management effects on serum muscle enzyme activity as markers of muscle health would assist interpretation of serum muscle enzyme activity and guide management to reduce myopathy risk.ObjectivesTo investigate associations between serum muscle enzyme activity and management factors in endurance horses.Study designCross‐sectional study.MethodsOne hundred endurance horses competing in four endurance events (offering distances of 20‐120 km) in south‐eastern Australia were observed. Data were collected from official horse logbooks, pre‐and post‐race serum samples, an owner questionnaire of pre‐race and race management of horses and the Australian Endurance Riders Association results database. Multivariable linear regression modelling tested associations between management factors and serum muscle enzyme activity.ResultsFirst leg speed, distance raced, number of rest days pre‐race, and pre‐race activity of aspartate aminotransferase (AST) and creatine kinase (CK) explained 47.3% of the variance in post‐race CK. As first leg speed increased by 1 km/h, CK activity increased by 25.8% (95% CI 11%‐35%). Race distances >80 km increased post‐race CK activity by 124% (95% CI 116%‐145%). Each additional pre‐race rest day increased post‐race CK activity by 30.5% (95% CI 11%‐42%). Modelling a 10% increase in pre‐race CK and pre‐race AST activity was associated with post‐race CK activity increasing by 7.3% (95% CI 3%‐14.4%) and 8.5% (95% CI 0.3%‐14.2%) respectively. Horses experiencing training distances >40 km and a greater number of rest days prior to race day developed increased pre‐race AST and CK activity respectively.Main limitationsOwner questionnaires may be subject to bias. Limited data were available to model ride terrain, horse fitness, ration detail and myopathy. Muscle biopsies were not used to confirm myopathy.ConclusionsNearly half of the variation in post‐race CK activity observed can be attributed to management factors unrelated to myopathy, suggesting increased CK activity may not be pathognomonic for myopathy. We advise caution in relying solely on serum muscle enzyme activity for diagnosis of myopathy until the strength of association between CK and myopathy is further ascertained in future studies.

Metagenomic investigation of potential abortigenic pathogens in foetal tissues from Australian horses

BackgroundAbortion in horses leads to economic and welfare losses to the equine industry. Most cases of equine abortions are sporadic, and the cause is often unknown. This study aimed to detect potential abortigenic pathogens in equine abortion cases in Australia using metagenomic deep sequencing methods.ResultsAfter sequencing and analysis, a total of 68 and 86 phyla were detected in the material originating from 49 equine abortion samples and 8 samples from normal deliveries, respectively. Most phyla were present in both groups, with the exception of Chlamydiae that were only present in abortion samples. Around 2886 genera were present in the abortion samples and samples from normal deliveries at a cut off value of 0.001% of relative abundance. Significant differences in species diversity between aborted and normal tissues was observed. Several potential abortigenic pathogens were identified at a high level of relative abundance in a number of the abortion cases, including Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Streptococcus equi subspecies zooepidemicus, Pantoea agglomerans, Acinetobacter lwoffii, Acinetobacter calcoaceticus and Chlamydia psittaci.ConclusionsThis work revealed the presence of several potentially abortigenic pathogens in aborted specimens. No novel potential abortigenic agents were detected. The ability to screen samples for multiple pathogens that may not have been specifically targeted broadens the frontiers of diagnostic potential. The future use of metagenomic approaches for diagnostic purposes is likely to be facilitated by further improvements in deep sequencing technologies.

Hepatitis viruses: prevalence of equine parvovirus‐hepatitis virus and equine hepacivirus in France and Australia

Background: Recent identification of viruses considered responsible for Theiler’s disease (acute hepatitis) in horses include equine parvovirus-hepatitis (EqPV-H) and the most likely of several flaviviruses, equine hepacivirus (EqHV). Both of these viruses have now been detected in North America, Asia, and Europe. Objectives: To determine the prevalence of EqPV-H and EqHV in French and Australian horses and to analyse their respective phylogenetic relationships. Study design: Cross-sectional. Methods: Clinically documented sera from 188 Australian horses and 259 French horses collected between 2016-2019 were analysed. qPCRs validated according to the NF47-600 standard were used to detect EqPV-H and EqHV in sera. Sequencing for phylogenetic analysis was performed on two NS1 fragments (516 nt and 587 nt) for EqPV-H and one NS5B fragment (308 nt) for EqHV. A phylogenic network was built using a Median Joining Network algorithm. Results: 1) EqPV-H: 12/259 (4.6%) and 6/188 (3.2%) samples from French and Australian horses were positive, respectively. Viral loads ranged from 2.3e05 to 6.5e05 copies genome/ml. 2) EqHV: 5/259 (1.9%) and 21/188 (11.2%) samples from French and Australian horses were positive, respectively. Viral loads ranged from 6.1e04 to 1.4e08 copies genome/ml. Both EqPV-H (587 nt fragment) and EqHV phylogenetic analyses showed that Australian strains were clustered, while overall distribution was more heterogenous in French horses. Main limitations: The study population is built by accessing laboratory submissions and potentially biased. The 516 nt NS1 fragment could not be sequenced. Conclusions: This is the first report of EqPV-H detection in both Australian and French horses. The EqPV-H prevalence was similar between the two countries (p-value=0.6) although phylogenetic differences were observed between the two populations. This is also the first reported detection of EqHV in Australian horses, with a higher prevalence when compared with French horses.

Age-Related Changes in the Behaviour of Domestic Horses as Reported by Owners.

Simple SummarySome treatments for common problem behaviours in domestic horses can compromise horse welfare. Such behaviours can be the manifestation of pain, confusion and conflict. In contrast, among the desirable attributes in horses, boldness and independence are two important behavioural traits that affect the fearfulness, assertiveness and sociability of horses when interacting with their environment, objects, conspecifics and humans. Shy and socially dependent horses are generally more difficult to manage and train than their bold and independent counterparts. Previous studies have shown how certain basic temperament traits predict the behavioural output of horses, but few have investigated how the age of the horse and the age it was when started being trained under saddle affect behaviour. Using 1940 responses to the Equine Behaviour Assessment and Research Questionnaire (E-BARQ), the current study explored the behavioural evidence of boldness and independence in horses and how these related to the age of the horse. Results revealed age-related effects on boldness and independence of horses. Older horses were bolder than younger horses, but horses started under saddle at an older age were less bold and independent than those started at a younger age. Additionally, significant differences in boldness and independence relating to specific breeds and primary equestrian disciplines also emerged. Finally, riders with eight or more years of riding experience reported having more independent horses than those who had ridden their whole lives. Understanding how horses’ ages affect behavioural traits can improve horse–rider matching and potentially also optimise welfare.The broad traits of boldness and independence in domestic horses can affect their usefulness and, indirectly, their welfare. The objective of the current study was to explore associations between attributes that reflect equine boldness and independence with both the age of horses and the age at which they were started under saddle, as well as other variables including breed, colour and primary equestrian discipline. All data were sourced from responses (n = 1940) to the 97-question online Equine Behaviour Assessment and Research Questionnaire (E-BARQ). Twenty E-BARQ items from the dataset were selected to reflect boldness and independence and were tested for univariate significance at p < 0.2. Multivariable modelling of the effect of age on remaining traits was assessed by an ordinal logistic regression, using a cumulative log odds model. This revealed that older horses were bolder (p = 0.012). However, horses started under saddle at an older age were less bold and less independent (p = 0.040 and p = 0.010, respectively). Australian Stock Horses were bolder and more independent (p = 0.014 and p = 0.007, respectively) than crossbreed horses. Horses used for breeding conformation (p = 0.039), working equitation (p = 0.045), eventing (p = 0.044) and traditional working horses (p = 0.034) were bolder than those used for other disciplines. Dressage (p = 0.039) and therapy (p = 0.040) horses were less bold than horses used for other disciplines. Stallions were bolder (p = −0.034) than geldings. Brown (p = 0.049) and chestnut (p = 0.027) horses were less bold than bay horses. Compared to crossbreed horses, Thoroughbreds (p = 0.000) and companion horses (p = 0.017) were less bold whilst heavy horses (p = 0.029) and ponies (p = 0.044) were bolder. Compared to pleasure horses, mounted games horses (p = 0.033) were less independent whereas working equitation horses (p = 0.020) were more independent. Riders with more than eight years’ experience reported more independence in their horses (p = 0.015) than those who had ridden their whole lives. The study findings suggest that boldness and independence are separate traits and only boldness was associated with the age of the horse. Factors that relate to desirable boldness and independence are important in ridden horses because they can affect rider safety. Results from this study should improve horse–rider matching and thereby potentially enhance horse welfare.

Spillover of bat borne Rubulavirus in Australian horses – Horses as sentinels for emerging infectious diseases

Background: Over 1000 horses are investigated annually for Hendra virus (HeV)-like illness, of which very few (<1%) test HeV positive. In Australia, in addition to HeV, other zoonotic viruses have affected horses including Australian bat lyssavirus, West Nile Virus (Kunjin), Murray Valley encephalitis virus and Ross River virus. In 1997, Menangle virus (MenPV), family Paramyxovirus, genus Rubulavirus, caused severe reproductive failure in pigs and influenza-like illness with rash in two piggery staff. MenPV has been isolated from Australian flying fox urine along with novel related rubulaviruses and HeV. We describe evidence of natural exposure to bat-borne rubulaviruses in Australian horses as well as seroconversion suggesting causality of severe respiratory illness. Methods and materials: Three-hundred-and-seventy-four horses were tested by a multiplex microsphere-based immunoassay (MIA) for IgG against MenPV nucleocapsid (N) protein and a subset also against Tioman virus (TioPV) N protein and MenPV hemagglutinin-neuraminidase (HN) protein. Confirmatory testing comprised immunofluorescence assay (IFA) on Vero cells infected with MenPV and related rubulaviruses. Results: Median fluorescence intensities (MFI) against MenPV N and a prior prevalence estimate of 20% were used in a Bayesian latent class model to determine appropriate cut-offs for positive test classification. Assay sensitivity was estimated assuming a specificity of both 95% and 99%. MFI reflecting potentially significant IgG to MenPV N protein was demonstrated in 34% (94/274) of horses with high perceived flying fox exposure (29% in QLD and 32% in NSW) whereas horses without plausible exposure recorded insignificant MFI. IFA confirmed antibodies to three of five related flying fox rubulaviruses tested (MenPV, Yeppoon virus and Grove virus). Case presentations: Two young-adult geldings developed severe acute respiratory illness in 2016 featuring obtunded demeanour, tachypnoea, tachycardia, congested/ hyperaemic mucous membranes, pyrexia and serous nasal discharge. Convalescent sera revealed a greater-than 10-fold increase in MFI to MenPV N (965 to 12,886). IFA confirmed antibodies to MenPV present in convalescent sera only. Conclusion: We highlight the potential of optimised syndromic surveillance for emerging zoonoses and One Health benefit of horses as sentinels of emerging infectious disease. Future research should determine the significance of rubulavirus spillover to horses and any associated human health risks.

Spillover of bat borne rubulavirus in Australian horses – Horses as sentinels for emerging infectious diseases

Background: Over 1000 horses are investigated annually for Hendra virus (HeV)-like illness, of which very few (<1%) test HeV positive. In Australia, in addition to HeV, other zoonotic viruses have affected horses including Australian bat lyssavirus, West Nile Virus (Kunjin), Murray Valley encephalitis virus and Ross River virus. In 1997, Menangle virus (MenPV), family Paramyxovirus, genus Rubulavirus, caused severe reproductive failure in pigs and influenza-like illness with rash in two piggery staff. MenPV has been isolated from Australian flying fox urine along with novel related rubulaviruses and HeV. We describe evidence of natural exposure to bat-borne rubulaviruses in Australian horses as well as seroconversion suggesting causality of severe respiratory illness. Methods and materials: Three-hundred-and-seventy-four horses were tested by a multiplex microsphere-based immunoassay (MIA) for IgG against MenPV nucleocapsid (N) protein and a subset also against Tioman virus (TioPV) N protein and MenPV hemagglutinin-neuraminidase (HN) protein. Confirmatory testing comprised immunofluorescence assay (IFA) on Vero cells infected with MenPV and related rubulaviruses. Results: Median fluorescence intensities (MFI) against MenPV N and a prior prevalence estimate of 20% were used in a Bayesian latent class model to determine appropriate cut-offs for positive test classification. Assay sensitivity was estimated assuming a specificity of both 95% and 99%. MFI reflecting potentially significant IgG to MenPV N protein was demonstrated in 34% (94/274) of horses with high perceived flying fox exposure (29% in QLD and 32% in NSW) whereas horses without plausible exposure recorded insignificant MFI. IFA confirmed antibodies to three of five related flying fox rubulaviruses tested (MenPV, Yeppoon virus and Grove virus). Case presentations: Two young-adult geldings developed severe acute respiratory illness in 2016 featuring obtunded demeanour, tachypnoea, tachycardia, congested/ hyperaemic mucous membranes, pyrexia and serous nasal discharge. Convalescent sera revealed a greater-than 10-fold increase in MFI to MenPV N (965 to 12,886). IFA confirmed antibodies to MenPV present in convalescent sera only. Conclusion: We highlight the potential of optimised syndromic surveillance for emerging zoonoses and One Health benefit of horses as sentinels of emerging infectious disease. Future research should determine the significance of rubulavirus spillover to horses and any associated human health risks.

Thinking with a landscape: the Australian Alps, horses and pedagogical considerations

AbstractThis paper proposes some possibilities for thinking with a landscape as a pedagogical concept, inspired by posthuman theory. The idea of thinking with a landscape is enacted in the Australian Alps (AA), concentrating on the contentious environmental dilemma involving introduced horses and their management in this bio-geographical location. The topic of horses is of pedagogical relevance for place-responsive outdoor environmental educators as both a location-specific problem and an example of a troubling issue. The paper has two objectives for employing posthuman thinking. Firstly, it experiments with the alternative methodological possibilities that posthuman theory affords for outdoor environmental education, including new ways of conducting educational research. Secondly, it explores how thinking with a landscape as a pedagogical concept may help open ways of considering the dilemma that horses pose. The pedagogical concept is enacted through some empirical events which sketch human–horse encounters from the AA. These sketches depict some of the pedagogical conversations and discursive pathways that encounters can provoke. Such encounters and conversations are ways of constructing knowledge of the landscape, covering multiple species, perspectives and discursive opportunities. For these reasons, this paper may be of relevance for outdoor environmental educators, those interested in the AA or posthuman theorists.

Comparison of the Head and Neck Positions in Ridden Horses Advertised in an Australian Horse Sales Magazine: 2005 Versus 2018

The impact of head and neck position (HNP) on horse welfare has received much attention in the scientific literature within the last two decades. Studies have identified physiological and behavioral signs of distress in horses ridden for prolonged time in an HNP with their noseline behind the vertical (BTV), which may compromise their welfare. The objective of this study was to compare potential differences of HNPs shown in horse sales photographs advertised in an Australian horse sales magazine (Horse Deals) from the years 2005 and 2018. In addition, factors potentially impacting HNPs, such as type of tack presented in (e.g., noseband type), riding discipline, and competition experience of the horse, were investigated. The sample population (n = 570) comprised horses ridden with headgear and bit in walk, trot, or canter/gallop, advertised in an Australian horse sales magazine. Issues from April 2005 and October/November 2018 were selected. Head and neck position was categorized as BTV, on the vertical (OV), slightly in front of the vertical (IFV), or extremely in front of the vertical (EIFV; any HNP >30° IFV). Data were analyzed using the chi-squared test and post hoc testing via a multiple regression approach through SPSS and test of proportions via the Z-score calculator for two independent population proportions. Analysis of combined data from years 2005 and 2018 showed 47.0% (n = 570) of the horse sample population were advertised with HNPs BTV. Behind-the-vertical HNP was observed as the predominant HNP (57.8%; n = 268) in the warmblood/eventers/show/performance (WESP) category (P < .0005). In 2005, 53.4% (n = 303) of the sample population were ridden BTV compared with 39.7% (n = 267) in 2018 (P < .001), 12.9% (n = 303) were OV in 2005 compared with 15.0% (n = 267) in 2018 (P > .05), and 10.9% (n = 303) were IFV in 2005 compared with 27.3% (n = 267) in 2018 (P < .0004). These results suggest a positive development with fewer vendors/riders selecting images where the horse’s nose was BTV. However, this may be explained by the larger proportion of horses advertised in the WESP category in 2005 (63.0%; n = 303) versus 2018 (28.5%; n = 267), and the WESP category predominantly comprised of dressage, jumper, and eventing horses. In addition, the reduction of HNPs BTV from 53.4% (n = 303) in 2005 to 39.7% (n = 267) in 2018 could be attributed to the observation that in 2018, a larger proportion of horses were listed in categories that do not require the horses to be worked with a flexed HNP referred to as “on-the-bit” (e.g., western, endurance, Australian sStock horses). The HNP BTV remains preferential by a substantial proportion of the horse-owning public when advertising horses for sale, particularly in disciplines where the horse is worked in a flexed HNP or “on-the-bit.”