533 results on '"Stevenson, MA"'
Search Results
2. Early life events associated with first lactation reproductive performance in southwest Victorian pasture‐based dairy herds
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Chuck, GM, primary, Mansell, PD, additional, Stevenson, MA, additional, and Izzo, MM, additional
- Published
- 2023
- Full Text
- View/download PDF
3. Early life events associated with first lactation reproductive performance in southwest Victorian pasture‐based dairy herds.
- Author
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Chuck, GM, Mansell, PD, Stevenson, MA, and Izzo, MM
- Subjects
LACTATION ,ANIMAL herds ,DAIRY cattle ,PROPORTIONAL hazards models ,WEIGHT gain - Abstract
This was a prospective cohort study to determine how events from birth until first calving affect reproductive performance in the first lactation in pasture‐based dairy herds in Victoria, Australia. Events during the preweaning (0 to 84 days), weaning to first breeding (85 to 473 days) and first breeding to first calving periods (474 to 804 days) were recorded and their association with reproductive performance during the first lactation was quantified. Reproductive performance outcomes included the number of days from first mating start date to first service (MSD‐S1) and the number of days from first mating start date to first conception (MSD‐CON). Predictors for reproductive performance included: passive transfer status as a calf; season of birth; age and breed of the dam; breed; the presence or absence of dystocia at the time of the heifer's birth; active feeding of colostrum versus being left on the dam for colostrum intake; presence of twinning; the presence or absence of preweaning diarrhoea; preweaning, prepubertal and postpubertal average daily gain; the presence or absence of periparturient disease at first calving; age at first calving; body condition score at first calving; sex of the first‐born calf; the presence or absence of a stillborn calf at the first calving and requirement of assistance at first calving. Two Cox proportional hazards regression models were developed: the first for early life event variables associated with MSD‐S1 and the second for early life events associated with MSD‐CON. Heifers born in autumn and winter had 2.89 (95% CI 1.50 to 5.59, P = 0.002) times and 1.97 (95% CI 1.12 to 3.44, P = 0.018) times the daily hazard of being inseminated compared with heifers born in spring, respectively. For the MSD‐S1 analyses heifers that gave birth to a live calf had 1.64 (95% CI 1.14 to 2.36, P = 0.008) times the daily hazard of being inseminated compared with heifers that had a stillborn calf. Increases in weight gain during the first breeding to first calving period by 0.1 kg/day increments increased the daily hazard of first insemination by a factor of 1.10 (95% CI 1.00 to 1.22, P = 0.043). Heifers that experienced periparturient disease had a significantly lower hazard of conception per day compared with heifers that did not experience periparturient disease at the first calving (HR 0.67, 95% CI 0.50 to 0.91, P = 0.009). Increases in weight gain during the first breeding to first calving period by 0.1 kg/day increased the daily hazard of conception by a factor of 1.10 (95% CI 1.01 to 1.21, P = 0.038). We conclude that of all the growth periods assessed in this study, events that occurred during the first breeding to first calving period (474 to 804 days) had the greatest association with reproductive performance in the first lactation. There should be a focus on increasing growth rates during this period and reducing the risk of stillbirth and periparturient disease to improve reproductive performance in the subsequent mating period after calving. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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4. National participation levels in the 2017–2018 Australian thoroughbred racing season
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Flash, ML, primary, Shrestha, K, additional, Stevenson, MA, additional, and Gilkerson, JR, additional
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- 2023
- Full Text
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5. Estimation of a Within-Herd Transmission Rate for African Swine Fever in Vietnam
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Le, VP, Lan, NT, Canevari, JT, Villanueva-Cabezas, JP, Padungtod, P, Trinh, TBN, Nguyen, VT, Pfeiffer, CN, Oberin, MV, Firestone, SM, Stevenson, MA, Le, VP, Lan, NT, Canevari, JT, Villanueva-Cabezas, JP, Padungtod, P, Trinh, TBN, Nguyen, VT, Pfeiffer, CN, Oberin, MV, Firestone, SM, and Stevenson, MA
- Abstract
We describe results from a panel study in which pigs from a 17-sow African swine fever (ASF) positive herd in Thái Bình province, Vietnam, were followed over time to record the date of onset of ASF signs and the date of death from ASF. Our objectives were to (1) fit a susceptible-exposed-infectious-removed disease model to the data with transmission coefficients estimated using approximate Bayesian computation; (2) provide commentary on how a model of this type might be used to provide decision support for disease control authorities. For the outbreak in this herd, the median of the average latent period was 10 days (95% HPD (highest posterior density interval): 2 to 19 days), and the median of the average duration of infectiousness was 3 days (95% HPD: 2 to 4 days). The estimated median for the transmission coefficient was 3.3 (95% HPD: 0.4 to 8.9) infectious contacts per ASF-infectious pig per day. The estimated median for the basic reproductive number, R0, was 10 (95% HPD: 1.1 to 30). Our estimates of the basic reproductive number R0 were greater than estimates of R0 for ASF reported previously. The results presented in this study may be used to estimate the number of pigs expected to be showing clinical signs at a given number of days following an estimated incursion date. This will allow sample size calculations, with or without adjustment to account for less than perfect sensitivity of clinical examination, to be used to determine the appropriate number of pigs to examine to detect at least one with the disease. A second use of the results of this study would be to inform the equation-based within-herd spread components of stochastic agent-based and hybrid simulation models of ASF.
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- 2023
6. A cross‐sectional survey of risk factors for the presence of Coxiella burnetii in Australian commercial dairy goat farms
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Hou, KW, primary, Wiethoelter, AK, additional, Stevenson, MA, additional, Soares Magalhaes, RJ, additional, Lignereux, L, additional, Caraguel, C, additional, Stenos, J, additional, Vincent, G, additional, Aleri, JW, additional, and Firestone, SM, additional
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- 2022
- Full Text
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7. Investigation of Weather Triggers Preceding Outbreaks of Acute Bovine Liver Disease in Australia.
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Manthorpe, EM, Rawlin, GT, Stevenson, MA, Woolford, L, Caraguel, CGB, Manthorpe, EM, Rawlin, GT, Stevenson, MA, Woolford, L, and Caraguel, CGB
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Acute bovine liver disease (ABLD) is a hepatic disease affecting cattle sporadically in southern Australia, characterised histologically by striking periportal hepatocellular necrosis. The cause of ABLD is unknown; however, the seasonality and acute presentation of outbreaks suggest mycotoxin involvement. We described the geographical and seasonal occurrence of ABLD reports from 2010 to 2020 in Victoria, Australia, and explored potential weather triggers preceding 26 outbreaks occurring across 23 properties using a case-crossover design. Outbreaks occurred most frequently in autumn/early winter and in herds located along the southern coastal plain of Victoria, and occasionally within the low-lying regions of the Great Dividing Range. Lactating adult dairy cattle represented the most reported cases. We observed a significant association between an increase in average daily dewpoint in the 15 days preceding an ABLD outbreak, suggesting that dew formation may be a key determinant for this disease. Our findings support the etiology of a potent hepatotoxic agent that requires moisture for proliferation and/or toxin production.
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- 2022
8. Identifying scenarios and risk factors for Q fever outbreaks using qualitative analysis of expert opinion
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Tan, TS-E, Hernandez-Jover, M, Hayes, LM, Wiethoelter, AK, Firestone, SM, Stevenson, MA, Heller, J, Tan, TS-E, Hernandez-Jover, M, Hayes, LM, Wiethoelter, AK, Firestone, SM, Stevenson, MA, and Heller, J
- Abstract
Q fever is an important zoonotic disease perceived to be an occupational hazard for those working with livestock. Outbreaks involving large numbers of people are uncommon, but the increasing case incidence coupled with changing environmental and industry conditions that promote transmission of Q fever has raised concerns that large and serious outbreaks could become more frequent. The aim of this study was to use expert opinion to better understand how large Q fever outbreaks might occur in an Australian context and to document factors believed to be drivers of disease transmission. Focus groups were conducted with human and animal health professionals across several Australian states. All discussions were recorded, transcribed verbatim and imported into NVIVO for thematic analysis. Four anthropogenic risk factors (disease awareness, industry practices, land use, human behaviour) and three ecological risk factors (physical environment, agent dissemination, animal hosts) emerged from the data. Analysis of expert opinions pointed to the existence of numerous scenarios in which Q fever outbreaks could occur, many of which depict acquisition in the wider community outside of traditional at-risk occupations. This perception of the expansion of Q fever from occupational-acquisition to community-acquisition is driven by greater overarching economic, political and socio-cultural influences that govern the way in which people live and work. Findings from this study highlight that outbreaks are complex phenomena that involve the convergence of diverse elements, not just that of the pathogen and host, but also the physical, political and socioeconomic environments in which they interact. A review of the approaches to prevent and manage Q fever outbreaks will require a multisectorial approach and strengthening of community education, communication and engagement so that all stakeholders become an integrated part of outbreak mitigation and response.
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- 2022
9. Validation of an Indirect Immunofluorescence Assay and Commercial Q Fever Enzyme-Linked Immunosorbent Assay for Use in Macropods
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Barrs, VR, Tolpinrud, A, Stenos, J, Chaber, A-L, Devlin, JM, Herbert, C, Pas, A, Dunowska, M, Stevenson, MA, Firestone, SM, Barrs, VR, Tolpinrud, A, Stenos, J, Chaber, A-L, Devlin, JM, Herbert, C, Pas, A, Dunowska, M, Stevenson, MA, and Firestone, SM
- Abstract
Kangaroos are considered to be an important reservoir of Q fever in Australia, although there is limited knowledge on the true prevalence and distribution of coxiellosis in Australian macropod populations. Serological tests serve as useful surveillance tools, but formal test validation is needed to be able to estimate true seroprevalence rates, and few tests have been validated to screen wildlife species for Q fever. In this study, we modified and optimized a phase-specific indirect immunofluorescence assay (IFA) for the detection of IgG antibodies against Coxiella burnetii in macropod sera. The assay was validated against the commercially available ID Screen Q fever indirect multispecies enzyme-linked immunosorbent assay (ELISA) kit (IDVet, Grabels, France) to estimate the diagnostic sensitivity and specificity of each assay, using Bayesian latent class analysis. A direct comparison of the two tests was performed by testing 303 serum samples from 10 macropod populations from the east coast of Australia and New Zealand. The analysis indicated that the IFA had relatively high diagnostic sensitivity (97.6% [95% credible interval [CrI], 88.0 to 99.9]) and diagnostic specificity (98.5% [95% CrI, 94.4 to 99.9]). In comparison, the ELISA had relatively poor diagnostic sensitivity (42.1% [95% CrI, 33.7 to 50.8]) and similar diagnostic specificity (99.2% [95% CrI, 96.4 to 100]) using the cutoff values recommended by the manufacturer. The estimated true seroprevalence of C. burnetii exposure in the macropod populations included in this study ranged from 0% in New Zealand and Victoria, Australia, up to 94.2% in one population from New South Wales, Australia.
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- 2022
10. A cross-sectional survey of risk factors for the presence of Coxiella burnetii in Australian commercial dairy goat farms
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Hou, KW, Wiethoelter, AK, Stevenson, MA, Soares Magalhaes, RJ, Lignereux, L, Caraguel, C, Stenos, J, Vincent, G, Aleri, JW, Firestone, SM, Hou, KW, Wiethoelter, AK, Stevenson, MA, Soares Magalhaes, RJ, Lignereux, L, Caraguel, C, Stenos, J, Vincent, G, Aleri, JW, and Firestone, SM
- Abstract
The largest Australian farm-based outbreak of Q fever originated from a dairy goat herd. We surveyed commercial dairy goat farms across Australia by testing bulk tank milk (BTM) samples using a commercial indirect enzyme-linked immunosorbent assay and two quantitative polymerase chain reactions (PCRs). Of the 66 commercial dairy goat herds on record, managers from 61 herds were contacted and 49 provided BTM samples. Five of the surveyed herds were positive on at least one of the diagnostic tests, thus herd-level apparent prevalence was 10% (95% confidence interval [CI] 4 to 22). True prevalence was estimated to be 3% (95% credible interval: 0 to 18). Herd managers completed a questionnaire on herd management, biosecurity and hygiene practices and risk factors were investigated using multivariable logistic regression. Herds with >900 milking does (the upper quartile) were more likely to be Coxiella burnetii positive (odds ratio = 6.75; 95% CI 1.65 to 27.7) compared with farms with ≤900 milking does. The odds of BTM positivity increased by a factor of 2.53 (95% CI 1.51 to 4.22) for each order of magnitude increase in the number of goats per acre. C. burnetii was not detected in samples from the majority of the Australian dairy goat herds suggesting there is an opportunity to protect the industry and contain this disease with strengthened biosecurity practices. Intensification appeared associated with an increased risk of positivity. Further investigation is required to discriminate the practices associated with an increased risk of introduction to disease-free herds, from practices associated with maintenance of C. burnetii infection in infected dairy goat herds.
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- 2022
11. Performance Evaluation and Validation of Air Samplers To Detect Aerosolized Coxiella burnetii
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Uzal, F, Abeykoon, AMH, Poon, M, Firestone, SM, Stevenson, MA, Wiethoelter, AK, Vincent, GA, Uzal, F, Abeykoon, AMH, Poon, M, Firestone, SM, Stevenson, MA, Wiethoelter, AK, and Vincent, GA
- Abstract
Coxiella burnetii, the etiological agent of Q fever, is an intracellular zoonotic pathogen transmitted via the respiratory route. Once released from infected animals, C. burnetii can travel long distances through air before infecting another host. As such, the ability to detect the presence of C. burnetii in air is important. In this study, three air samplers, AirPort MD8, BioSampler, and the Coriolis Micro, were assessed against a set of predetermined criteria in the presence of three different aerosolized C. burnetii concentrations. Two liquid collection media, phosphate-buffered saline (PBS) and alkaline polyethylene glycol (Alk PEG), were tested with devices requiring a collection liquid. Samples were tested by quantitative polymerase chain reaction assay (qPCR) targeting the single-copy com1 gene or multicopy insertion element IS1111. All air samplers performed well at detecting airborne C. burnetii across the range of concentrations tested. At high nebulized concentrations, AirPort MD8 showed higher, but variable, recovery probabilities. While the BioSampler and Coriolis Micro recovered C. burnetii at lower concentrations, the replicates were far more repeatable. At low and intermediate nebulized concentrations, results were comparable in the trials between air samplers, although the AirPort MD8 had consistently higher recovery probabilities. In this first study validating air samplers for their ability to detect aerosolized C. burnetii, we found that while all samplers performed well, not all samplers were equal. It is important that these results are further validated under field conditions. These findings will further inform efforts to detect airborne C. burnetii around known point sources of infection. IMPORTANCE Coxiella burnetii causes Q fever in humans and coxiellosis in animals. It is important to know if C. burnetii is present in the air around putative sources as it is transmitted via inhalation. This study assessed air samplers (AirPort MD8, BioSamp
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- 2022
12. 2006 Presidential Address: The Evolution of the Profession
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Stevenson, MA
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- 2006
13. Factors associated with racing performance and career duration for Victorian‐born Thoroughbreds
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Flash, ML, primary, Crabb, HK, additional, Hitchens, PL, additional, Firestone, SM, additional, Stevenson, MA, additional, and Gilkerson, JR, additional
- Published
- 2021
- Full Text
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14. Participation of Victorian Thoroughbreds in the racing industry: a whole‐of‐population benchmark
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Flash, ML, primary, Crabb, HK, additional, Hitchens, PL, additional, Firestone, SM, additional, Stevenson, MA, additional, and Gilkerson, JR, additional
- Published
- 2021
- Full Text
- View/download PDF
15. A descriptive retrospective study on mortality and involuntary culling in beef and dairy cattle production systems of Western Australia (1981–2018)
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Aleri, JW, primary, Lyons, A, additional, Laurence, M, additional, Coiacetto, F, additional, Fisher, AD, additional, Stevenson, MA, additional, Irons, PC, additional, and Robertson, ID, additional
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- 2021
- Full Text
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16. Pet health insurance reduces the likelihood of pre-surgical euthanasia of dogs with gastric dilatation-volvulus in the emergency room of an Australian referral hospital
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Anderson, S, primary, Stevenson, MA, additional, and Boller, M, additional
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- 2021
- Full Text
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17. Variations in the median sacral crest and angulation of the first sacral spinous process associated with sacrocaudal fusion in greyhounds
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Ismail, SMY, Murray, CM, Stevenson, MA, Yen, H-H, Davies, HMS, Ismail, SMY, Murray, CM, Stevenson, MA, Yen, H-H, and Davies, HMS
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- 2021
18. A descriptive retrospective study on mortality and involuntary culling in beef and dairy cattle production systems of Western Australia (1981-2018)
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Aleri, JW, Lyons, A, Laurence, M, Coiacetto, F, Fisher, AD, Stevenson, MA, Irons, PC, Robertson, ID, Aleri, JW, Lyons, A, Laurence, M, Coiacetto, F, Fisher, AD, Stevenson, MA, Irons, PC, and Robertson, ID
- Abstract
Identifying and quantifying the relative frequency of involuntary losses is an essential first step in developing fit-for-purpose herd health programmes. The objective of this study was to provide an estimate of the relative frequency of reasons for mortality among south-west Western Australian beef and dairy cattle, based on necropsy findings from a university-based veterinary pathology referral centre over 38 years. A total of 904 cattle were submitted for postmortem examination throughout the study period. Gastrointestinal, cardiopulmonary and reproductive conditions were the most common causes of mortality in cattle submitted for necropsy at Murdoch University for the period 1981-2018. In dairy cattle, the common problems were gastrointestinal (bloat, abomasal displacements) 18% (59/320), cardiovascular (traumatic reticulo-pericarditis) 9% (30/320) and respiratory conditions (pneumonia) 8% (27/320). In beef cattle, the most common conditions were gastrointestinal (bloat, rumen acidosis) 11% (39/358), reproductive (metritis) 11% (38/358), cardiovascular (traumatic reticulo-pericarditis) 7% (25/358), respiratory (pneumonia) 7% (24/358), lameness (fractures) 6%, (21/358) and hepatobiliary conditions (blue-green algae poisoning, hepatotoxicity) 6% (21/358). Selection bias and missing data were potential confounders in this study. Although necropsy investigations provide useful information on animal mortalities and avenues for future herd health programmes, there is a need to standardise data capture methods and disease definition criteria, and conduct more detailed recording of data both at the farm level and at necropsy diagnostic centres.
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- 2021
19. Pet health insurance reduces the likelihood of pre-surgical euthanasia of dogs with gastric dilatation-volvulus in the emergency room of an Australian referral hospital
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Anderson, S, Stevenson, MA, Boller, M, Anderson, S, Stevenson, MA, and Boller, M
- Abstract
AIMS: To determine the association between the presence of pet health insurance and the risk of euthanasia at the time of diagnosis for dogs with gastric dilatation-volvulus (GDV). METHODS: Insurance status at the time of GDV diagnosis was sought for a cohort of 147 non-referred, confirmed cases of GDV that presented to the emergency department of a university-based veterinary hospital in Australia between 2008 and 2017. Insurance status was obtained from the medical record (n=18) or after contacting the owners by phone using a standardised questionnaire (n=129). Animal, clinical and outcome data was retrospectively compiled in a research database. The primary outcome measure was whether or not the dog was euthanised before surgery. The Mantel-Haenszel procedure was used to quantify the association between the presence of pet health insurance and the risk of euthanasia at the time of diagnosis for dogs with GDV, adjusting for the confounding effect of age at the time of presentation using Bayesian methods. RESULTS: Of the 69 dogs for which insurance information could be obtained, 10 (14%) cases were insured at the time of the GDV event and 59 (86%) cases were not. The majority of non-insured dogs (37/59; 63 (95% CI=50-74)%) were euthanised before surgery, while none (0 (95% CI=0-28)%) of the insured dogs were euthanised at that time (p<0.001). Of the 32 insured and non-insured dogs that underwent surgery, four dogs (13 (95% CI=5-28)%) did not survive to hospital discharge. Three dogs (9%) were euthanised during or after surgery and one dog (3%) experienced cardiopulmonary arrest during treatment. The majority of dogs for which insurance status was known did not survive to hospital discharge (41/69; 59%), and 90 (95% CI=7-96)% of deaths were caused by euthanasia prior to surgery. Uninsured dogs were 5.0 (95% credible interval=1.8-26) times more likely to undergo presurgical euthanasia compared with insured dogs. CONCLUSIONS: Euthanasia prior to treatment was most com
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- 2021
20. Variation in the seventh lumbar vertebra and the lumbosacral junction morphometry associated with the sacrocaudal fusion in greyhounds
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Ismail, SMY, Murray, CM, Stevenson, MA, Hung-Hsun, Y, Davies, HMS, Ismail, SMY, Murray, CM, Stevenson, MA, Hung-Hsun, Y, and Davies, HMS
- Abstract
The lumbosacral joint is where the 7th lumbar vertebra (L.7) articulates within the sacrum. It is a clinically important area in the dog because of its relatively large range of motion. The current study aims to determine the possible differences in the length of the L.7 vertebra and the angle of the lumbosacral junction among greyhounds of standard and those of fused sacra, and to determine the potential association of sex, body mass and type of fused sacrum (standard and fused) on the morphology of the L.7 vertebra and the angle of the lumbosacral junction. Radiographs of 55 greyhound cadavers were used for radiographing; all radiographic images were stored and measured using X-ray acquisition software, and then analysed using descriptive statistics, multiple linear regression and logistic regression. The results of this study showed a significant increase (p < .008) in the length of the L.7 vertebra and the angle of the lumbosacral junction (p < .028) in greyhounds with fused sacra comparing with those of standard sacra, but the L.6 length was not significant (p = .431). Differences have been found in the length of L.7 vertebra and the angle of the lumbosacral junction in greyhounds. It was found that in greyhounds, any variation in the sacrum's anatomical features may alter the structure of the surrounding anatomical structures such as the L.7 vertebra and lumbosacral junction.
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- 2021
21. Brucella suis Seroprevalence and Associated Risk Factors in Dogs in Eastern Australia, 2016 to 2019
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Kneipp, CC, Sawford, K, Wingett, K, Malik, R, Stevenson, MA, Mor, SM, Wiethoelter, AK, Kneipp, CC, Sawford, K, Wingett, K, Malik, R, Stevenson, MA, Mor, SM, and Wiethoelter, AK
- Abstract
Brucella suis is a zoonotic disease of feral pigs that also affects pig hunting dogs, pig hunters, veterinarians and veterinary staff. In recent years the incidence of B. suis in the eastern Australian states of New South Wales (NSW) and Queensland (QLD) has increased. A cross-sectional study was conducted to document the seroprevalence, geographical extent and risk factors for B. suis in dogs at-risk of contracting the disease. Eligible dogs were those that were known to hunt or consume feral pig meat. Dogs were enrolled through private veterinary clinics and/or directly by District Veterinarians in six regions of NSW and QLD. Blood was collected by venepuncture and tested for B. suis antibodies using the Rose Bengal Test (RBT) followed by a Complement Fixation Test (CFT) if they returned a positive RBT. Owners were invited to complete a questionnaire on the dogs' signalment, husbandry including hunting practices and locations, and any clinical signs referable to brucellosis. Of the 317 dogs included in the prevalence survey, 21 were seropositive returning a survey-adjusted true seroprevalence of 9.3 (95% CI 0.45 to 18) B. suis positive dogs per 100 dogs at-risk. True seroprevalence ranged from 0 to 24 B. suis positive dogs per 100 across eastern Australia, with the highest prevalence in central west NSW and southern QLD. Adjusted for other factors, dogs that shared a household with other seropositive dogs and those that traveled away from their home regions to hunt were more likely to be seropositive. Clinical signs at presentation were not predictive of serostatus, with seropositive and seronegative dogs equally likely to present with signs consistent with brucellosis. The results obtained from this study show that B. suis exposure is relatively common in dogs that have contact with feral pigs, with one in 10 testing seropositive. Further studies are needed to understand the progression and risk of transmission from seropositive dogs.
- Published
- 2021
22. Participation of Victorian Thoroughbreds in the racing industry: a whole-of-population benchmark
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Flash, ML, Crabb, HK, Hitchens, PL, Firestone, SM, Stevenson, MA, Gilkerson, JR, Flash, ML, Crabb, HK, Hitchens, PL, Firestone, SM, Stevenson, MA, and Gilkerson, JR
- Abstract
The proportion of Thoroughbred (TB) horses that commence training and eventually race, is an important industry-level indicator of how successful it is at producing horses suitable for racing. It is also of interest to the wider community and is central to the issue of whether there is overbreeding in the Australian TB industry. This study investigated the training and racing records for the 2005 and 2010 Victorian TB foal crops to determine the proportion of TBs that train and race, and the age of entering training and first race start. Subsets of the foal crop were also examined to determine if premier yearling sale cohorts would produce selection bias. The Australian Stud Book (ASB) registered 7662 TB horses born in Victoria in 2005 (n = 4116) and 2010 (n = 3546). Of these, 5614 (73%) entered training and 4868 (64%) started in at least one race. Fourteen percent (n = 1045) of the study cohort had their first race start as 2-year-olds and 35% (n = 2644) had their first start as 3-year-olds. A higher proportion of TB horses that attended premier yearling sales entered training (93%) and raced (84%). This study established a baseline for training and racing milestones, such as the proportion and age that horses commenced training, and age of first start using population-level data. It also established that the use of subsets of the population can introduce selection bias.
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- 2021
23. Factors associated with racing performance and career duration for Victorian-born Thoroughbreds
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Flash, ML, Crabb, HK, Hitchens, PL, Firestone, SM, Stevenson, MA, Gilkerson, JR, Flash, ML, Crabb, HK, Hitchens, PL, Firestone, SM, Stevenson, MA, and Gilkerson, JR
- Abstract
The number of horses leaving the Australian Thoroughbred (TB) racing industry each year is of concern to animal welfare advocates, public and regulators. A horse's previous athletic performance is a significant driver of retirement from racing. Racehorse performance can be measured in terms of the total number of starts, duration of racing and prize money earned. This study investigated Australian racing records for the 2005 and 2010 Victorian TB foal crops to identify factors associated with total number of starts, racing career duration, prize money earned and age of last race start-up to the 10-year-old racing season. Racing Australia registered 4,577 TB horses born in Victoria in 2005 (n = 2,506) and 2010 (n = 2,071) that raced in Australia. Horses that started racing at 2-years of age had fewer race starts in their first racing season but an increased total number of starts, prize money and duration of racing. The median age of last start (LS) was five (Q1 4; Q3 7) years. Horses that had won a race, had a maximum handicap rating of 61 or above and those racing over distances of more than 2,400 m had an increased racing career duration and an age of last race start greater than 6-years of age. Horses participating in jumps races (n = 63) had the longest careers and older age of LS. These horses were more likely to have had a handicap rating over 80 and were just as likely to start their racing careers as 2-years-olds.
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- 2021
24. Sample Size Estimation in Veterinary Epidemiologic Research
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Stevenson, MA and Stevenson, MA
- Abstract
In the design of intervention and observational epidemiological studies sample size calculations are used to provide estimates of the minimum number of observations that need to be made to ensure that the stated objectives of a study are met. Justification of the number of subjects enrolled into a study and details of the assumptions and methodologies used to derive sample size estimates are now a mandatory component of grant application processes by funding agencies. Studies with insufficient numbers of study subjects run the risk of failing to identify differences among treatment or exposure groups when differences do, in fact, exist. Selection of a number of study subjects greater than that actually required results in a wastage of time and resources. In contrast to human epidemiological research, individual study subjects in a veterinary setting are almost always aggregated into hierarchical groups and, for this reason, sample size estimates calculated using formulae that assume data independence are not appropriate. This paper provides an overview of the reasons researchers might need to calculate an appropriate sample size in veterinary epidemiology and a summary of sample size calculation methods. Two approaches are presented for dealing with lack of data independence when calculating sample sizes: (1) inflation of crude sample size estimates using a design effect; and (2) simulation-based methods. The advantage of simulation methods is that appropriate sample sizes can be estimated for complex study designs for which formula-based methods are not available. A description of the methodological approach for simulation is described and a worked example provided.
- Published
- 2021
25. Structural anatomy and morphometric analyses of sacra in greyhounds
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Ismail, SMY, Murray, CM, Stevenson, MA, Yen, H-H, Adamu, JY, Davies, HMS, Ismail, SMY, Murray, CM, Stevenson, MA, Yen, H-H, Adamu, JY, and Davies, HMS
- Abstract
This study was conducted to provide structural and morphological data on the sacra of greyhounds. Descriptive quantitative investigation was carried out on 171 sacra of greyhound`s cadavers and then classified into standard and fused sacra based on the number of fused sacral vertebrae. The weight, length and width of sacrum of sacra were measured. Both standard (59%) and fused sacra (41%) were identified. The average length and width of the standard sacrum were found to be 46.14 ± 2.53 mm and 57.89 ± 3.54 mm, respectively. The sacral length was 1.61-mm longer in males (p < .01), and the sacral width was 0.46-mm shorter in males but not significant (p = .51). The average weight of a standard sacrum was 26.54 ± 4.55 g and was 1.18 g heavier in males but not statistically significant (p = .24). Results showed that one-kilogram increase in the body mass was associated with a 0.3 mm (p < .001) increase in sacral length, and a 0.54 mm (p < .001) increase in sacral width, respectively. The morphological data of the standard and fused sacra provided in this study might help the veterinary community to improve treatment and rehabilitation and help the trainer to design the right training protocol for racing greyhounds. In addition, the results of this study are a step to understand the sacrum's functions and how the greyhound's body functions and future studies are required to investigate the biological importance of these findings.
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- 2021
26. The effects of parasitism on ewes for prime lamb production in western Victoria
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Kirk, B, Larsen, JWA, Anderson, N, Stevenson, MA, Kirk, B, Larsen, JWA, Anderson, N, and Stevenson, MA
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Context Internal parasites are estimated to cost the Australian sheep industry AUD436 million per annum (p.a.). Aims To assess the effects of parasitism in flocks producing prime lambs in the 500–700 mm p.a rainfall. area of Victoria. Methods Ewes on two farms that followed ‘best practice’ gastrointestinal parasite control programs (BP) and two farms that did not (regionally typical, TYP) were compared. Separate cohorts of ewes were monitored from pregnancy scanning to their subsequent joining each year for three consecutive seasons. Observations included worm egg count (WEC), bodyweight, condition score and presence of breech soiling (dag). These were compared between groups that were treated to suppress parasitism (SUP) and those treated according to the usual program used on that farm (NSUP). Data from individual ewes were analysed using a multivariable, mixed-effects regression model. Key results After adjusting for known confounders, SUP ewes were 1.2 (95% CI 0.80–1.6) kg heavier than NSUP ewes. Mature SUP ewes were significantly heavier than NSUP ewes at their next joining on 6 of 18 occasions, mostly following winters when ewes experienced nutritional stress. Ewe hoggets and Merino ewes were generally more susceptible to parasitism than mature non-Merino ewes; single-bearing ewes were less susceptible than those bearing twins. The effects of parasitism were reduced when peri-parturient ewes had an optimal condition score and grazed adequate pastures. Conclusions Ewes were more vulnerable to parasitism when immature, twin-bearing, or under nutritional stress. Some of the greatest differences between SUP and NSUP ewes occurred following periods of low feed availability and/or ewe condition score. The difference between the mean bodyweight of SUP and NSUP Merinos was not always greater than that of the non-Merinos. WECs are not a sole reliable indicator of the effects of parasitism in this class of sheep. Implications Immature or twin-bearing ewes, and those in
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- 2021
27. Drivers of exit and outcomes for Thoroughbred racehorses participating in the 2017-2018 Australian racing season
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Smith, RL, Shrestha, K, Gilkerson, JR, Stevenson, MA, Flash, ML, Smith, RL, Shrestha, K, Gilkerson, JR, Stevenson, MA, and Flash, ML
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The destinations of Thoroughbred (TB) racehorses exiting the racing industry is a high-profile issue with ethical and welfare implications of interest to both animal welfare groups and racing regulators. This cross-sectional study investigated the reasons that TBs temporarily or permanently exited racing and training in Australia in the 2017-2018 racing season and the outcomes for these horses post-racing. An online questionnaire was sent to the last registered trainers of a representative sample of 2,509 'inactive' TBs. Inactive horses were defined as those horses that were recorded as 'active' but had not trialled or raced in the last 6 months of the racing season or had an inactive status recorded in the Racing Australia database. Of the 1,750 responses received, the largest group of inactive TBs had permanently exited the racing industry (45% retired, 5.3% deceased). A relatively large group exited racing temporarily (43%) but participated in the racing industry in the following season. The reasons for retirement were predominantly voluntary, such as poor performance or owner's request. Almost one third of retirements were due to injuries with tendon or ligament problems the most frequently conditions listed. The median age at retirement was five (Q1 4; Q3 7) years. Extrapolation of the survey results to the population of horses racing or training in Australia in 2017-2018 (n = 37,750) show that that 17% of the population retire each year and 2.1% die. These estimates provide benchmarks for industry and animal welfare organisations to resource and measure the effectiveness of interventions.
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- 2021
28. A systematic approach to illuminate a new hot spot of avian influenza virus circulation in South Vietnam, 2016-2017
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Kien, TL, Stevenson, MA, Isoda, N, Lam, TN, Duc-Huy, C, Tien, NN, Long, VN, Tien, NT, Tung, TL, Matsuno, K, Okamatsu, M, Sakoda, Y, Kien, TL, Stevenson, MA, Isoda, N, Lam, TN, Duc-Huy, C, Tien, NN, Long, VN, Tien, NT, Tung, TL, Matsuno, K, Okamatsu, M, and Sakoda, Y
- Abstract
In South Vietnam, live bird markets (LBMs) are key in the value chain of poultry products and spread of avian influenza virus (AIV) although they may not be the sole determinant of AIV prevalence. For this reason, a risk analysis of AIV prevalence was conducted accounting for all value chain factors. A cross-sectional study of poultry flock managers and poultry on backyard farms, commercial (high biosecurity) farms, LBMs and poultry delivery stations (PDSs) in four districts of Vinh Long province was conducted between December 2016 and August 2017. A total of 3597 swab samples were collected from birds from 101 backyard farms, 50 commercial farms, 58 sellers in LBMs and 19 traders in PDSs. Swab samples were submitted for AIV isolation. At the same time a questionnaire was administered to flock managers asking them to provide details of their knowledge, attitude and practices related to avian influenza. Multiple correspondence analysis and a mixed-effects multivariable logistic regression model were developed to identify enterprise and flock manager characteristics that increased the risk of AIV positivity. A total of 274 birds were positive for AIV isolation, returning an estimated true prevalence of 7.6% [95% confidence interval (CI): 6.8%-8.5%]. The odds of a bird being AIV positive if it was from an LBM or PDS were 45 (95% CI: 3.4-590) and 25 (95% CI: 1.4-460), respectively, times higher to the odds of a bird from a commercial poultry farm being AIV positive. The odds of birds being AIV positive for respondents with a mixed (uncertain or inconsistent) level and a low level of knowledge about AI were 5.0 (95% CI: 0.20-130) and 3.5 (95% CI: 0.2-62), respectively, times higher to the odd of birds being positive for respondents with a good knowledge of AI. LBMs and PDSs should receive specific emphasis in AI control programs in Vietnam. Our findings provide evidence to support the hypothesis that incomplete respondent knowledge of AI and AIV spread mechanism were ass
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- 2021
29. Observations of different types of sacra in Greyhounds based on the occurrence of sacrocaudal fusion
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Ismail, SMY, Murray, CM, Stevenson, MA, Yen, H-H, Davies, HMS, Ismail, SMY, Murray, CM, Stevenson, MA, Yen, H-H, and Davies, HMS
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Little attention has been paid to the normal fusion of the vertebrae of greyhounds despite the common occurrence of sacrocaudal fusion. The current study aimed to investigate and provide data on the morphology of different types of fused sacra (B, C and D) in greyhounds and also to determine the potential association between the sex, body mass and morphology of fused sacra (S. Weight, S. Length and S. Width) in greyhounds. The sacra were collected from 171 greyhounds from Melbourne, Australia. After classifying the sacra based on the occurrence and types of the sacrocaudal fusion, they were measured for weight of the sacrum, length of sacrum and the width of sacrum. Multiple linear regression analyses were used to quantify the association between weight of the sacrum (as the outcome variable) type of sacrum (A, B, C and D), body mass and sex (as explanatory variables). The results proved that there are measurable differences between each type of fused sacra (B, C and D) and the standard sacra (A). In addition, this study showed that sex or body mass do not influence the occurrence of different types of fusion. The results of this study showed that the occurrence of sacrocaudal fusions was independent of body size in this population of greyhounds. Sacrocaudal fusion might affect the biomechanics in greyhounds independently of effects of body size.
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- 2021
30. Spatio-temporal distribution of outbreaks of highly pathogenic avian influenza virus subtype H5N1 in Vietnam, 2015-2018
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Loth, L, Long, TP, Stevenson, MA, Loth, L, Long, TP, and Stevenson, MA
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Despite strong commitments of the central and provincial veterinary authorities in Vietnam to control highly pathogenic avian influenza H5N1 (HPAI-H5N1) in poultry and to diminish the risk of human infection, outbreaks continue to occur in poultry. This study describes the spatio-temporal distribution of HPAI-H5N1 outbreaks in Vietnam for the period December 2014-April 2018 using the space-time K-function and the space-time scan statistic. The space-time K-function analyses showed statistically significant spatio-temporal clustering of HPAI-H5N1 outbreaks in poultry during the study period of up to 50 days and 60 kilometres. The space-time scan statistic test identified three statistically significant space-time clusters of HPAI-H5N1 in the south of the country where the incidence of HPAI-H5N1 outbreaks was greater than that expected if outbreaks were randomly distributed in space and time. The analyses indicated shortfalls in the effectiveness of control measures used to control HPAI-H5N1 throughout the study period. Development of a better understanding of the relative impact of HPAI-H5N1 control measures (depopulation of infected flocks, vaccination, movement restrictions) on space-time interaction would allow animal health authorities to focus their efforts on control measures shown to have the greatest relative effect.
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- 2021
31. Antibiotic Prescription in Veterinary Consultations in Bhutan: A Retrospective Cross-Sectional Study
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Villanueva-Cabezas, JP, Rinzin, K, Dorjee, S, Tshewang, P, Namgyel, U, Sharma, PM, Stevenson, MA, McVernon, J, Villanueva-Cabezas, JP, Rinzin, K, Dorjee, S, Tshewang, P, Namgyel, U, Sharma, PM, Stevenson, MA, and McVernon, J
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The veterinary prescription of antibiotics in low- and middle-income countries (LMIC) remains largely undocumented. In Bhutan, however, the national veterinary service keeps records of their activities and prescriptions, which offer an opportunity to establish a benchmark to assess the use of these agents in this and other LMIC. A cross-sectional retrospective study was designed and 2,266 handwritten veterinary records from 2017 were sampled from 23 animal health premises (AHPs) to estimate individual and an overall proportion of consultations that resulted in an antibiotic prescription. The frequency of antibiotic prescription per species, type of AHP, and according to WHO's AWaRe index and OIE list of priority antimicrobials were also explored. It was estimated that 31% (95% confidence interval: 29-33%; intracluster correlation: 0.03) of the veterinary consultations resulted in an antibiotic prescription. The incidence of antibiotic prescription was highest in consultations of poultry across AHP. Across species, diarrhea and wounds were frequently treated with broad-spectrum antibiotics including sulfonamides, tetracyclines, trimethoprim + sulfa, and penicillin. Between 45% and 70% antibiotics prescribed correspond to AWaRe's access group and up to 25% to AWaRe's watch group. Over 70% of antibiotics dispensed in veterinary consultations for any species correspond to the OIE's veterinary critically important antimicrobial agents. Overall, the study demonstrated positive features of veterinary antimicrobial stewardship in Bhutan, given the conservative proportion of consultation that results in this type of prescription and the type of antibiotic prescribed. Although the veterinary service closely follows the Bhutanese Standard Treatment Guidelines, the prescription of antibiotics to key species should be closely monitored. Our study suggests that further improvements of antibiotic stewardship can be achieved through standardisation of antibiotic prescription to som
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- 2021
32. Spatiotemporal and risk analysis of H5 highly pathogenic avian influenza in Vietnam, 2014-2017
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Lam, TN, Stevenson, MA, Firestone, SM, Sims, LD, Duc, HC, Long, VN, Tien, NN, Kien, TL, Isoda, N, Matsuno, K, Okamatsu, M, Kida, H, Sakoda, Y, Lam, TN, Stevenson, MA, Firestone, SM, Sims, LD, Duc, HC, Long, VN, Tien, NN, Kien, TL, Isoda, N, Matsuno, K, Okamatsu, M, Kida, H, and Sakoda, Y
- Abstract
The aim of this study was to describe the spatiotemporal distribution of H5 HPAI outbreak reports for the period 2014-2017 and to identify factors associated with H5 HPAI outbreak reports. Throughout the study period, a total of 139 outbreaks of H5 HPAI in poultry were reported, due to either H5N1 (96 outbreaks) or H5N6 (43 outbreaks) subtype viruses. H5N1 HPAI outbreaks occurred in all areas of Vietnam while H5N6 HPAI outbreaks were only reported in the northern and central provinces. We counted the number of H5N1 and H5N6 outbreak report-positive districts per province over the four-year study period and calculated the provincial-level standardized morbidity ratio for H5N1 and H5N6 outbreak reports as the observed number of positive districts divided by the expected number. A mixed-effects, zero-inflated Poisson regression model was developed to identify risk factors for outbreak reports of each H5N1 and H5N6 subtype virus. Spatially correlated and uncorrelated random effects terms were included in this model to identify areas of the country where outbreak reports occurred after known risk factors had been accounted-for. The presence of an outbreak report in a province in the previous 6-12 months increased the provincial level H5N1 outbreak report risk by a factor of 2.42 (95% Bayesian credible interval [CrI] 1.27-4.60) while 1000 bird increases in the density of chickens decreased provincial level H5N6 outbreak report risk by a factor of 0.65 (95% CrI 0.38 to 0.97). We document distinctly different patterns in the spatial and temporal distribution of H5N1 and H5N6 outbreak reports. Most of the variation in H5N1 report risk was accounted-for by the fixed effects included in the zero-inflated Poisson model. In contrast, the amount of unaccounted-for risk in the H5N6 model was substantially greater than the H5N1 model. For H5N6 we recommend that targeted investigations should be carried out in provinces with relatively large spatially correlated random effect terms
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- 2020
33. Differences in the clinical practice of small animal CPR before and after the release of the RECOVER guidelines: Results from two electronic surveys (2008 and 2017) in the United States and Canada
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Donaldson, L, Stevenson, MA, Fletcher, DJ, Gillespie, I, Kellett-Gregory, L, Boller, M, Donaldson, L, Stevenson, MA, Fletcher, DJ, Gillespie, I, Kellett-Gregory, L, and Boller, M
- Abstract
Objective To assess whether the clinical approach to CPR has changed following the publication of the Reassessment Campaign on Veterinary Resuscitation (RECOVER) guidelines in 2012. Design Internet-based survey. Setting Academia and referral practice. Subjects Four hundred and ninety-one small animal veterinarians in clinical practice in the United States and Canada. Interventions An internet-based survey assessing the clinical approach to small animal CPR was circulated with the assistance of veterinary professional organizations on 2 separate occasions: prior to (2008) and following (2017) publication of the 2012 (RECOVER) guidelines. Survey questions identical to both surveys solicited details of clinician approaches to CPR preparedness, basic life support (BLS), and advanced life support (ALS). Respondents were grouped into level of expertise (board-certified specialists [BCS, n = 202] and general practitioners in emergency clinics [GPE, n = 289]), and year of response to the survey (2008, n = 171; 2017, n = 320). Measurements and Main Results Compliance with the RECOVER guidelines pertaining to CPR preparedness (P < 0.01), BLS (P < 0.01), and ALS P < 0.01) was consistently higher in respondents to the 2017 survey compared to those of the 2008 survey. Being a BCS was associated with significantly higher compliance with the RECOVER recommendations than GPE in the domains of preparedness (P = 0.02), BLS (P < 0.01), and ALS (P < 0.01). Increases in age of the respondent had a negative effect on compliance with the BLS guidelines (P < 0.01), while gender had no effect. Conclusions Compared to 2008, current practices in small animal CPR in the North American emergency and critical care community shifted toward those recommended in the RECOVER guidelines across all CPR domains. This supports the notion that uptake of the RECOVER guidelines among veterinary emergency or critical care clinicians was sufficient to lead to a change in the practice of CPR.
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- 2020
34. SnakeMap: four years of experience with a national small animal snake envenomation registry
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Boller, M, Kelers, K, Stevenson, MA, Winkel, KD, Hardjo, S, Heller, J, Judge, PR, Ong, HM, Padula, AM, Reddrop, C, Santos, LCP, Sharp, CR, Smart, L, Swindells, KL, Tabrett, D, Wierenga, JR, Boller, M, Kelers, K, Stevenson, MA, Winkel, KD, Hardjo, S, Heller, J, Judge, PR, Ong, HM, Padula, AM, Reddrop, C, Santos, LCP, Sharp, CR, Smart, L, Swindells, KL, Tabrett, D, and Wierenga, JR
- Abstract
SnakeMap is a national cloud-based, veterinary snakebite registry. It was designed to prospectively collect data of the clinical circumstances and temporospatial information on cases of snake envenomation in dogs and cats. We herein introduce the project and summarise the data from the first 4 years of SnakeMap. The registry is a veterinary community-based online database allowing case entry from veterinary hospitals across Australia. Registry data comprise hospital characteristics, patient characteristics, envenoming snake type, treatment and outcome variables, including time and geolocation of the snake bite. We present summative information on select key variables from the SnakeMap registry (1 July 2015 to 30 June 2019). Twenty-eight hospitals from 6 states/territories entered 624 cases into the registry, including 419 dogs (67%) and 205 cats (33%). Bite time was available in 216 animals of which 90 (42%) were reported to be bitten in the 3 hours between 03:00 pm and 05:59 pm; median bite to presentation interval was 60 (interquartile range [IQR] 30, 211) minutes in dogs and 95 (IQR 41, 238) minutes in cats. Bites occurred in the owner's yard in 356 dogs (85%) and 53 cats (26%). A snake venom detection kit was used in 172 cases (28%) and antivenom was administered in 523 cases (85%). Most animals (n = 534, 88%) survived to discharge (median hospitalisation of 25 [IQR 16, 62] hours). SnakeMap effectively collects relevant clinical data from dogs and cats with presumed snake bite and provides locally specific information on the epidemiology of snake envenomation in small animals.
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- 2020
35. A case-control study to identify risk factors for adult-onset idiopathic megaoesophagus in Australian dogs, 2017-2018
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Renwick, M, Stevenson, MA, Wiethoelter, A, Mansfield, C, Renwick, M, Stevenson, MA, Wiethoelter, A, and Mansfield, C
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BACKGROUND: Epidemiological investigations were carried out following detection of an outbreak of megaoesophagus in Victorian Police working dogs in early 2018 and an increase in the number of canine megaoesophagus cases reported by companion animal veterinarians in Eastern Australia starting in late 2017. VetCompass Australia data were used to quantify the incidence of canine megaoesophagus for the period January 2012 to February 2018 and a matched case-control study carried out to identify individual animal risk factors for canine megaoesophagus in 2017-2018. RESULTS: There was a 7-fold increase in the incidence rate of canine megaoesophagus from 2014 (0.11 [95% CI 0.02 to 0.58] cases per 100,000 dogs per day) to 2018 (0.82 [95% CI 0.19 to 4.2] cases per 100,000 dogs per day). Since 2013, the incidence of megaoesophagus in Australia has shown a seasonal pattern, with greater numbers of cases diagnosed during the warmer months of the year. In the case-control study, use of Mars Petcare Advance Dermocare as a source of food was 325 (95% CI 64 to 1644) times greater for cases, compared with controls. CONCLUSIONS: Our analyses provide evidence that the feeding of Advance Dermocare was responsible for the majority of cases in the outbreak of megaoesophagus in Eastern Australia in 2017-2018. The increase in the incidence rate of megaoesophagus in Australia since 2014-2015 warrants further investigation.
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- 2020
36. Descriptive analysis of Thoroughbred horses born in Victoria, Australia, in 2010; barriers to entering training and outcomes on exiting training and racing
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Clegg, S, Flash, ML, Renwick, M, Gilkerson, JR, Stevenson, MA, Clegg, S, Flash, ML, Renwick, M, Gilkerson, JR, and Stevenson, MA
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The reasons for Thoroughbred (TB) horses not entering training or exiting the racing industry, are of interest to regulators, welfare groups and the broader community. Speculation about the outcomes of these horses threatens the community acceptance, or social license, of the TB breeding and racing industries. A representative survey of the 2010 Victorian born TB foal crop was used to determine the outcomes and reasons for exit for horses that had not entered training, or had exited training and racing by eight years of age. Horses exported for racing or breeding (4%), or that were still actively racing (7%) at the start of the follow up period were excluded from the study. An online questionnaire was sent to breeders or trainers of 3,176 TB horses eligible for enrolment in the study. Of the 2,005 (63%) responses received, the two most frequent outcomes were that the horse had either been retired or rehomed (65%), or deceased (16%). For the 1,637 TB horses that had entered training, the majority of retirements were voluntary (59%), followed by involuntary retirements due to health disorders (28%). For TBs that did not have an industry record of entering training (n = 368), death (34%), or retirement or being rehomed (27%), were the most frequent barriers to entering training. The median age of retirement for TBs that raced was five (Q1 4; Q3 6) years regardless of sex, or whether their first race start was at two, three or four years of age. Relatively large numbers of horses voluntarily retiring at five-years of age suggests that industry-level, rather than individual horse-level factors are the predominant influences on racing career duration.
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- 2020
37. Microbial contamination in drinking water at public outdoor recreation facilities in New Zealand
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Phiri, BJ, French, NP, Biggs, PJ, Stevenson, MA, Reynolds, AD, Garcia-R, JC, Hayman, DTS, Phiri, BJ, French, NP, Biggs, PJ, Stevenson, MA, Reynolds, AD, Garcia-R, JC, and Hayman, DTS
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AIM: The aim of our study was to assess the presence and risk of waterborne pathogens in the drinking water of outdoor facilities in New Zealand and track potential sources of microbial contamination in water sources. METHODS AND RESULTS: A serial cross-sectional study with a risk-based sample collection strategy was conducted at 15 public campgrounds over two summer seasons (2011-2012 and 2012-2013). Drinking water supplied to these campgrounds was not compliant with national standards, based on Escherichia coli as an indicator organism, in more than half of the sampling occasions. Campylobacter contamination of drinking water at the campgrounds was likely to be of wild bird origin. Faecal samples from rails (pukeko and weka) were 35 times more likely to return a Campylobacter-positive result compared to passerines. Water treatment using ultraviolet (UV) irradiation or a combination of filtration and UV irradiation or chemicals was more likely to result in water that was compliant with the national standards than water from a tap without any treatment. The use of filters alone was not associated with the likelihood of compliance. CONCLUSIONS: Providing microbiologically safe drinking water at outdoor recreational facilities is imperative to avoid gastroenteritis outbreaks. This requires an in-depth understanding of potential sources of contamination in drinking water sources and the installation of adequate water treatment facilities. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study provides evidence that drinking water without treatment or filter-only treatment in public campgrounds is unlikely to comply with national standards for human consumption and extra water treatment measures such as UV irradiation or chemical treatment are needed.
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- 2020
38. A cross-sectional pilot study to estimate the prevalence of and risk factors for leptospirosis inSouth-WesternVictorian dairy herds, 2017
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Erregger, E, Stevenson, MA, Beggs, DS, Oswin, S, Jagoe, SP, Mansell, PD, Pyman, MF, Erregger, E, Stevenson, MA, Beggs, DS, Oswin, S, Jagoe, SP, Mansell, PD, and Pyman, MF
- Abstract
Leptospirosis is a zoonosis, found worldwide, affecting many species of animals. We conducted a cross-sectional study to estimate the prevalence of Leptospira borgpetersenii sv Hardjo and Leptospira interrogans sv Pomona in cattle in dairy herds in South-Western Victoria, Australia. Fifty-three herds were enrolled in the study. Urine samples were collected from 15 late-lactation cows in each herd. A questionnaire was provided to herd managers at the time of each herd visit, asking them to describe the methods they used for controlling leptospirosis, including vaccination. Urine samples were pooled at the herd level and tested for leptospira spp. using real time PCR. Urine samples from individual cows within the positive pooled samples were then tested for Leptospira Hardjo and Leptospira Pomona using qPCR. Four of the 53 herds showed positive leptospirosis results giving an apparent prevalence of 8 (95% CI 2-18) leptospira-positive herds per 100 herds at risk. Based on the 53 completed questionnaires, leptospirosis vaccination programs were not compliant with label directions in 36 of the 52 vaccinated herds: 69 (95% CI 55-81) of 100 herd managers that routinely vaccinated for leptospirosis did not comply with label directions. One herd was completely unvaccinated. Based on our findings, we estimate that approximately 10% of dairy farms in South-Western Victoria are likely to be infected with leptospirosis. While most herds are vaccinating for leptospirosis, most are not doing so according to label directions. We conclude that herd managers need to be better educated regarding leptospirosis vaccination programs.
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- 2020
39. Variation in GPS and accelerometer recorded velocity and stride parameters of galloping Thoroughbred horses
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Morrice-West, AV, Hitchens, PL, Walmsley, EA, Stevenson, MA, Wong, ASM, Whitton, RC, Morrice-West, AV, Hitchens, PL, Walmsley, EA, Stevenson, MA, Wong, ASM, and Whitton, RC
- Abstract
BACKGROUND: With each stride, galloping horses generate large skeletal loads which influence bone physiology, and may contribute to musculoskeletal injury. Horse speed and stride characteristics are related, but the usefulness of using horse speed and distance travelled as a proxy for stride characteristics is unknown. OBJECTIVES: We aimed to determine stride characteristics, their variance and their relationship with speed in horses performing maximally. STUDY DESIGN: Retrospective cross-sectional analysis of archived data. METHODS: Stride characteristics obtained using GPS and inertial sensors in Thoroughbred horses were retrieved. Data per 200 m race segment ('sectionals') for horses competing in races (N = 25,259 race starts) were analysed to determine if speed predicted stride parameters. Multivariable mixed-effects linear regression models were fitted. RESULTS: Mean (±SD) stride length, stride count (number of strides per 200 m), duration and speed were 7.08 ± 0.39 m, 28.32 ± 1.56 strides/200 m, 0.43 ± 0.02 s/stride and 16.63 ± 1.04 m/s across all sectionals and starts. Speed and stride length decreased, and stride count increased with race progression (P < 0.001). Male sex, greater race distance, better finishing position and firmer track surfaces were associated with less strides per 200 m and longer stride durations. MAIN LIMITATIONS: Lack of an independent party validation of the measurement system used in this study. CONCLUSIONS: There was a substantial inter-horse variation in stride parameters, with speed predicting half or less of this variation. Speed alone does not fully explain stride characteristics in horses. Future studies aimed at investigating the impact of gait on bone biology and pathology would benefit from accounting for stride characteristics (eg length and duration).
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- 2020
40. Transmission network reconstruction for foot-and-mouth disease outbreaks incorporating farm-level covariates
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Dórea, FC, Firestone, SM, Hayama, Y, Lau, MSY, Yamamoto, T, Nishi, T, Bradhurst, RA, Demirhan, H, Stevenson, MA, Tsutsui, T, Dórea, FC, Firestone, SM, Hayama, Y, Lau, MSY, Yamamoto, T, Nishi, T, Bradhurst, RA, Demirhan, H, Stevenson, MA, and Tsutsui, T
- Abstract
Transmission network modelling to infer ‘who infected whom’ in infectious disease outbreaks is a highly active area of research. Outbreaks of foot-and-mouth disease have been a key focus of transmission network models that integrate genomic and epidemiological data. The aim of this study was to extend Lau’s systematic Bayesian inference framework to incorporate additional parameters representing predominant species and numbers of animals held on a farm. Lau’s Bayesian Markov chain Monte Carlo algorithm was reformulated, verified and pseudo-validated on 100 simulated outbreaks populated with demographic data Japan and Australia. The modified model was then implemented on genomic and epidemiological data from the 2010 outbreak of foot-and-mouth disease in Japan, and outputs compared to those from the SCOTTI model implemented in BEAST2. The modified model achieved improvements in overall accuracy when tested on the simulated outbreaks. When implemented on the actual outbreak data from Japan, infected farms that held predominantly pigs were estimated to have five times the transmissibility of infected cattle farms and be 49% less susceptible. The farm-level incubation period was 1 day shorter than the latent period, the timing of the seeding of the outbreak in Japan was inferred, as were key linkages between clusters and features of farms involved in widespread dissemination of this outbreak. To improve accessibility the modified model has been implemented as the R package ‘BORIS’ for use in future outbreaks.
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- 2020
41. Coxiella burnetii in the environment: A systematic review and critical appraisal of sampling methods
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Abeykoon, AMH, Clark, NJ, Soares Magalhaes, RJ, Vincent, GA, Stevenson, MA, Firestone, SM, Wiethoelter, AK, Abeykoon, AMH, Clark, NJ, Soares Magalhaes, RJ, Vincent, GA, Stevenson, MA, Firestone, SM, and Wiethoelter, AK
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Q fever is a zoonotic disease caused by the intracellular bacterium, Coxiella burnetii. Its primary mode of transmission is by inhalation of aerosols originating from infected animals and contaminated environments. The organism has a very low infective dose, can persist in the environment for long periods of time and large outbreaks fuelled by windborne spread have been previously reported. Detection of C. burnetii in the environment is therefore important during human and animal outbreak investigations and for the control and prevention of Q fever. This study aimed to systematically review and critically appraise the published literature on sampling methods used to detect C. burnetii from different environmental samples. A search of four electronic databases with subsequent hand searching identified 47 eligible articles published since 1935. These articles described sampling of dust, air, soil and liquids in attempts to detect C. burnetii during 19 Q fever outbreaks and in 28 endemic settings. Environmental positivity was most commonly associated with ruminant livestock populations. Evidence describing spatio-temporal characteristics and associated geographical dispersion gradients was limited. The most commonly tested sample type was dust which also yielded the highest bacterial loads of >108 bacteria/cloth. The MD8 (Sartorius) air sampler was used widely for air sampling. Soil was the only sample type for which a validated laboratory protocol was established specifically for C. burnetii. Each environmental sample type has its advantages and limitations which are discussed in detail and a simplified framework to guide decisions around environmental sampling for C. burnetii is provided. In any type of environmental sampling, it is recommended to use standardized and validated methods and to match the most ideal sampling strategy and timing with the research context. These conditions are essential to be considered when designing future Q fever management plans that
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- 2020
42. The Effect of Pet Insurance on Presurgical Euthanasia of Dogs With Gastric Dilatation-Volvulus: A Novel Approach to Quantifying Economic Euthanasia in Veterinary Emergency Medicine
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Boller, M, Nemanic, TS, Anthonisz, JD, Awad, M, Selinger, J, Boller, EM, Stevenson, MA, Boller, M, Nemanic, TS, Anthonisz, JD, Awad, M, Selinger, J, Boller, EM, and Stevenson, MA
- Abstract
Euthanasia of companion animals in veterinary emergency medicine is a common cause of death. Euthanasia is economic when it is the consequence of the pet owner's inability to afford essential treatment while a viable medical alternative to euthanasia exists. Gastric dilatation-volvulus (GDV) is an acute life-threatening emergency condition of dogs; if left untreated, rapid death is highly likely. Surgical treatment leads to survival of around 80-90% of dogs; however, such treatment is costly. Therefore, pre-surgical euthanasia may be largely economically motivated. Having pet insurance, a financial instrument to reduce the burden of unforeseen veterinary medical costs on pet owners, would be expected to abolish the risk for pre-surgical economic euthanasia. We therefore aimed to determine whether pet insurance attenuates the risk of pre-surgical economic euthanasia in dogs with GDV. Non-referred dogs (n = 260) with GDV and known insurance status seen at 24 emergency clinics over a 2-year period were included. Relevant data (e.g., insurance status, age, comorbidities, outcome) were retrospectively extracted from a pet insurer's claim records (insured animals) or from electronic medical records of participating hospitals (non-insured animals). Forty-one percent of dogs (106 of 260 dogs) did not survive to hospital discharge; 82 (77%) of non-survivors died before surgery, all through euthanasia. The pre-surgical euthanasia rate was 10% in insured and 37% in non-insured dogs (p < 0.001). When adjusted for the effect of age, deposit size, comorbidities, and blood lactate concentration, the absence of insurance increased the odds of pre-surgical euthanasia by a factor of 7.4 (95% CI 2.0 to 37; p = 0.002). Of dogs undergoing surgery, 86% survived to hospital discharge. Overall, 80% of insured animals and 53% of non-insured animals survived to hospital discharge (p < 0.001). Thus, insurance was associated with a marked decrease in risk of pre-surgical euthanasia indicating
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- 2020
43. A Participatory Investigation of Bovine Health and Production Issues in Pakistan
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Ghafar, A, McGill, D, Stevenson, MA, Badar, M, Kumbher, A, Warriach, HM, Gasser, RB, Jabbar, A, Ghafar, A, McGill, D, Stevenson, MA, Badar, M, Kumbher, A, Warriach, HM, Gasser, RB, and Jabbar, A
- Abstract
Systems to record the frequency of animal health events in Pakistan are limited. A participatory approach was used to address gaps in farmers' knowledge and understanding of bovine health and production issues in five agroecological zones (AEZs) of Pakistan. Participatory tools, including simple ranking, pairwise ranking, constraint impact scoring, and constraint profiling were used in group discussions with farmers and animal health professionals (AHPs) in six districts of two provinces, Punjab and Sindh. The results of the ranking activities showed that foot-and-mouth disease (FMD), clinical mastitis, ticks, hemorrhagic septicemia, reproductive disorders, blackleg, and endoparasites were the most important bovine health and production constraints for small-scale dairy farmers. Constraint impact scoring showed that the participants perceived that: (1) milk production was severely affected by FMD and mastitis; (2) blackleg and parasitism led to poor growth rates and reduced meat production; (3) reproductive disorders and mastitis caused major economic losses (due to the high cost of treatment); and (4) blackleg and hemorrhagic septicemia were the leading causes of mortality in cattle and buffaloes. Although there was strong agreement in responses and constraint impact scores between farmers and AHPs, farmers were more concerned about health issues that cause high mortalities, whereas AHPs emphasized the importance of disorders with a high economic impact. Despite socioeconomic differences among AEZs, farmers' knowledge about bovine health and production constraints was similar. The findings from this study revealed that farmers had limited understanding of the risk factors and routes of transmission of various infectious diseases of bovines, which emphasizes the need to develop and implement tailored extension programs in Pakistan to control contagious diseases of animals and to improve the profitability of small-scale dairy farmers.
- Published
- 2020
44. Barriers to entering race training before 4 years of age for Thoroughbred horses born in the 2014 Australian foal crop
- Author
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Rogers, C, Flash, ML, Wong, ASM, Stevenson, MA, Gilkerson, JR, Rogers, C, Flash, ML, Wong, ASM, Stevenson, MA, and Gilkerson, JR
- Abstract
Currently, there is a paucity of data on the barriers for Australian Thoroughbred horses transitioning from stud farm to racetrack. This paper reports the reasons why horses failed to enter race training and documents their exit destinations. Biographical records of Australian Thoroughbred horses born in 2014 were investigated to determine the number of horses that had not officially entered race training by the start of the 4-year old racing season (1 August 2018). Of the 13,677 foals born in 2014, 66% had commenced training and 51% had raced before the beginning of their 4-year-old season in Australia. A sampling frame based on the post code of the premises where foals were born and records from Racing Australia were used to select a geographically representative sample of the 2014 Australian Thoroughbred foal crop (n = 4,124). From the population eligible for sampling 1,275 horses that had not entered training were enrolled in the survey and their breeders were sent an online questionnaire with follow-up phone calls for those who had not responded. Of the 633 responses (50% of 1275) the most frequent outcomes for horses were: death (38%, n = 239), participation in the racing industry in their 4-year old racing season (24%, n = 154) and retirement (16%, n = 100) either as Australian Stud Book (ASB) bloodstock (n = 17), or as horses rehomed outside the Thoroughbred industry (n = 83). Illness or injury was the most frequent reason for horses not entering race training that were ASB bloodstock, rehomed or deceased. There was a loss of traceability at the point of sale with most horses sold at 1 year of age. This study provides important information on the reasons, alternative outcomes and gaps in traceability for horses not entering training prior to the 4-year-old racing season.
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- 2020
45. SnakeMap : four years of experience with a national small animal snake envenomation registry
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Boller, M, primary, Kelers, K, additional, Stevenson, MA, additional, Winkel, KD, additional, Hardjo, S, additional, Heller, J, additional, Judge, PR, additional, Ong, HM, additional, Padula, AM, additional, Reddrop, C, additional, Santos, LCP, additional, Sharp, CR, additional, Smart, L, additional, Swindells, KL, additional, Tabrett, D, additional, and Wierenga, JR, additional
- Published
- 2020
- Full Text
- View/download PDF
46. A cross‐sectional pilot study to estimate the prevalence of and risk factors for leptospirosis in South‐Western Victorian dairy herds, 2017
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Erregger, E, primary, Stevenson, MA, additional, Beggs, DS, additional, Oswin, S, additional, Jagoe, SP, additional, Mansell, PD, additional, and Pyman, MF, additional
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- 2020
- Full Text
- View/download PDF
47. Effect of a second treatment of prostaglandin F2α during the Ovsynch program on fixed‐time artificial insemination conception rates and luteolysis in split‐calving, pasture‐fed dairy cows
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Rheinberger, JM, primary, Colson, DD, additional, Beggs, DS, additional, Mansell, PD, additional, Stevenson, MA, additional, Rheinberger, RJ, additional, and Pyman, MF, additional
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- 2020
- Full Text
- View/download PDF
48. Factors associated with racing performance and career duration for Victorian‐born Thoroughbreds.
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Flash, ML, Crabb, HK, Hitchens, PL, Firestone, SM, Stevenson, MA, and Gilkerson, JR
- Subjects
RACE horses ,THOROUGHBRED horse ,ANIMAL welfare ,ATHLETIC ability ,TUBERCULOSIS ,FOALS ,HORSES ,HORSE racing - Abstract
The number of horses leaving the Australian Thoroughbred (TB) racing industry each year is of concern to animal welfare advocates, public and regulators. A horse's previous athletic performance is a significant driver of retirement from racing. Racehorse performance can be measured in terms of the total number of starts, duration of racing and prize money earned. This study investigated Australian racing records for the 2005 and 2010 Victorian TB foal crops to identify factors associated with total number of starts, racing career duration, prize money earned and age of last race start‐up to the 10‐year‐old racing season. Racing Australia registered 4,577 TB horses born in Victoria in 2005 (n = 2,506) and 2010 (n = 2,071) that raced in Australia. Horses that started racing at 2‐years of age had fewer race starts in their first racing season but an increased total number of starts, prize money and duration of racing. The median age of last start (LS) was five (Q1 4; Q3 7) years. Horses that had won a race, had a maximum handicap rating of 61 or above and those racing over distances of more than 2,400 m had an increased racing career duration and an age of last race start greater than 6‐years of age. Horses participating in jumps races (n = 63) had the longest careers and older age of LS. These horses were more likely to have had a handicap rating over 80 and were just as likely to start their racing careers as 2‐years‐olds. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
- View/download PDF
49. Participation of Victorian Thoroughbreds in the racing industry: a whole‐of‐population benchmark.
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Flash, ML, Crabb, HK, Hitchens, PL, Firestone, SM, Stevenson, MA, and Gilkerson, JR
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HORSE training ,HORSE racing ,RACE horses ,FOALS ,PARTICIPATION - Abstract
The proportion of Thoroughbred (TB) horses that commence training and eventually race, is an important industry‐level indicator of how successful it is at producing horses suitable for racing. It is also of interest to the wider community and is central to the issue of whether there is overbreeding in the Australian TB industry. This study investigated the training and racing records for the 2005 and 2010 Victorian TB foal crops to determine the proportion of TBs that train and race, and the age of entering training and first race start. Subsets of the foal crop were also examined to determine if premier yearling sale cohorts would produce selection bias. The Australian Stud Book (ASB) registered 7662 TB horses born in Victoria in 2005 (n = 4116) and 2010 (n = 3546). Of these, 5614 (73%) entered training and 4868 (64%) started in at least one race. Fourteen percent (n = 1045) of the study cohort had their first race start as 2‐year‐olds and 35% (n = 2644) had their first start as 3‐year‐olds. A higher proportion of TB horses that attended premier yearling sales entered training (93%) and raced (84%). This study established a baseline for training and racing milestones, such as the proportion and age that horses commenced training, and age of first start using population‐level data. It also established that the use of subsets of the population can introduce selection bias. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
- View/download PDF
50. An assessment of worm control practices used by alpaca farmers in Australia
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Rashid, MH, Stevenson, MA, Campbell, AJD, Vaughan, JL, Beveridge, I, Jabbar, A, Rashid, MH, Stevenson, MA, Campbell, AJD, Vaughan, JL, Beveridge, I, and Jabbar, A
- Abstract
This study aimed to assess current worm control practices used by Australian alpaca farmers with an online questionnaire survey. The questionnaire contained questions about farm demography and general husbandry practices, farmers' knowledge about gastrointestinal nematodes (GINs) and their importance, the use of worm control strategies and anthelmintics, and grazing management. A link for the questionnaire survey was sent to all (n = 954) registered members of the Australian Alpaca Association in July 2015. The response rate for the questionnaire was 25% (239/954). The majority of respondents were from small (≤ 50 alpacas; 64%, 153/239) followed by medium (50-100 alpacas; 24%, 57/239) and large (>100 alpacas; 12%, 29/239) farms. Findings revealed that the majority of respondents kept Huacaya alpacas to produce high-quality fibre and alpacas were usually kept with other domestic ruminants (e.g. cattle and sheep). Although half of alpaca farmers (114/220) perceived that GINs were an important health problem of alpacas, with Haemonchus spp. being the most common nematode, the majority of them (174/220) used anthelmintics for nematode control. Macrocyclic lactones, a commercial combination of four anthelmintics (abamectin, albendazole, closantel and levamisole) and monepantel were the three most commonly used dewormers by Australian alpaca farmers. Although a significant proportion (166/213) of respondents used a quarantine drench for alpacas, very few respondents were aware of strategic deworming and the issue of anthelmintic resistance. Alpaca farmers mostly used anthelmintics at the dose rate recommended for sheep (47%, 79/167) and cattle (9%, 15/167), though some used 1.5 (31%, 51/167) and 2 (13%, 22/167) times the dose rate recommended for sheep. The majority of small herds used anthelmintics at the dose rate recommended for sheep and cattle while medium and large herds used anthelmintics at 1.5 to 2 times the dose rate recommended for sheep. This study provides in
- Published
- 2019
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