Veterinary Clinical Sciences - Research Publications

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    Association of Thoroughbred Racehorse Workloads and Rest Practices with Trainer Success
    Morrice-West, AV ; Hitchens, PL ; Walmsley, EA ; Wong, ASM ; Whitton, RC (MDPI, 2021-11)
    Understanding the relationship between the training practices of Thoroughbred racehorses and race performance is important to ensure advice given to trainers for injury prevention or management is practical and consistent. We assessed associations between intended volume and speed of gallop training (i.e., typical workloads for horses free of injury or other performance limiting conditions) and rest practices on official trainer career and previous season success rates (rate of wins and places, prizemoney per start). Sixty-six Australian Thoroughbred trainers were surveyed. Multivariable negative binomial regression models were employed for the outcomes career and previous season wins and places, and linear regression models for prizemoney per start. Intended training workload was not associated with prizemoney. Pre-trial total galloping distances (≥13.3 m/s) between 7500 m and 15,000 m were associated with a higher rate of career wins, and previous season wins and places per start (p < 0.05). Slow-speed (13.3-14.3 m/s) galloping distance to trial between 5000 m to 12,500 m was associated with higher rate of career placings per start, with reduced performance over 12,500 m (p = 0.003). Greater time between race starts was associated with a greater rate of previous season wins and prizemoney per start until three weeks between starts, with decline in performance thereafter (p < 0.05). Greater frequency of rest breaks was associated with greater prizemoney per start earnt in the previous season (p ≤ 0.01). These results suggest that modifications to training programs aimed at injury prevention, such as avoiding long galloping distances, should not adversely affect trainer success.
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    Socializing One Health: an innovative strategy to investigate social and behavioral risks of emerging viral threats
    Saylors, K ; Wolking, DJ ; Hagan, E ; Martinez, S ; Francisco, L ; Euren, J ; Olson, SH ; Miller, M ; Fine, AE ; Nga, NTT ; Phuc, TM ; Kalengkongan, JD ; Consortium, P ; Kusumaningrum, T ; Latinne, A ; Pamungkas, J ; Safari, D ; Saputro, S ; Bamba, D ; Coulibaly, KJ ; Dosso, M ; Laudisoit, A ; Jean, KMN ; Dutta, S ; Islam, A ; Shano, S ; Mwanzalila, M ; Trupin, IP ; Gbakima, A ; Bangura, J ; Yondah, ST ; Karmacharya, D ; Shrestha, RD ; Kamta, MAM ; Mouiche, MMM ; Ndolo, HM ; Niama, FR ; Onikrotin, D ; Daszak, P ; Johnson, CK ; Mazet, JAK (BMC, 2021-05-14)
    In an effort to strengthen global capacity to prevent, detect, and control infectious diseases in animals and people, the United States Agency for International Development's (USAID) Emerging Pandemic Threats (EPT) PREDICT project funded development of regional, national, and local One Health capacities for early disease detection, rapid response, disease control, and risk reduction. From the outset, the EPT approach was inclusive of social science research methods designed to understand the contexts and behaviors of communities living and working at human-animal-environment interfaces considered high-risk for virus emergence. Using qualitative and quantitative approaches, PREDICT behavioral research aimed to identify and assess a range of socio-cultural behaviors that could be influential in zoonotic disease emergence, amplification, and transmission. This broad approach to behavioral risk characterization enabled us to identify and characterize human activities that could be linked to the transmission dynamics of new and emerging viruses. This paper provides a discussion of implementation of a social science approach within a zoonotic surveillance framework. We conducted in-depth ethnographic interviews and focus groups to better understand the individual- and community-level knowledge, attitudes, and practices that potentially put participants at risk for zoonotic disease transmission from the animals they live and work with, across 6 interface domains. When we asked highly-exposed individuals (ie. bushmeat hunters, wildlife or guano farmers) about the risk they perceived in their occupational activities, most did not perceive it to be risky, whether because it was normalized by years (or generations) of doing such an activity, or due to lack of information about potential risks. Integrating the social sciences allows investigations of the specific human activities that are hypothesized to drive disease emergence, amplification, and transmission, in order to better substantiate behavioral disease drivers, along with the social dimensions of infection and transmission dynamics. Understanding these dynamics is critical to achieving health security--the protection from threats to health-- which requires investments in both collective and individual health security. Involving behavioral sciences into zoonotic disease surveillance allowed us to push toward fuller community integration and engagement and toward dialogue and implementation of recommendations for disease prevention and improved health security.
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    Training practices, speed and distances undertaken by Thoroughbred racehorses in Victoria, Australia
    Morrice-West, A ; Hitchens, PL ; Walmsley, EA ; Stevenson, MA ; Whitton, RC (WILEY, 2020-03)
    BACKGROUND: Musculoskeletal injuries (MSI) in racehorses are commonly due to bone fatigue, a function of the number of cycles (strides) and the magnitude of load applied to the limb. These parameters can be estimated using speed and distance, with greater than 6000 m/month at a gallop (>14 m/s), in combination with canter distances greater than 44,000 m/month, reported to increase fracture risk. Despite their importance, there are limited data on the distances and speeds horses are exposed to during training. OBJECTIVES: Estimate training volume at different speeds undertaken by Australian Thoroughbred racehorses. STUDY DESIGN: Cross-sectional study. METHODS: Registered trainers (n = 66) in Victoria, Australia were surveyed. Questions were designed to assess the full training workload from initial pre-training to training performed to achieve and maintain race fitness, as well as information on rest periods. Descriptive analyses were stratified by trainer- and horse-level factors, with assessment of variance within and between groups. Cluster analyses were used to identify similar workload intensity groups. RESULTS: Horse-level factors (age, targeted race distance) were associated with workload (younger
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    A Cross Sectional Survey of International Horse-Racing Authorities on Injury Data Collection and Reporting Practices For Professional Jockeys
    O'Connor, S ; Hitchens, PL ; Bolwell, C ; Annan, R ; McGoldrick, A ; Fortington, L (ELSEVIER SCIENCE INC, 2021-09)
    Jockey injuries are common in professional horse-racing and can result in life-threatening or career-ending outcomes. Robust injury data are essential to understand the circumstances of injury occurrence and ultimately identify prevention opportunities. This study aimed to identify jockey injury surveillance practices of international horse-racing authorities (HRAs) and the specific data items collected and reported by each HRA. A cross-sectional survey of representatives (e.g. Chief Medical Officer) from international HRAs was conducted. An online and paper questionnaire was designed comprised of 32 questions. Questions considered the barriers and facilitators to data collection within each HRA, and where available, what data were collected and reported by HRAs. Representatives from 15 international racing jurisdictions were included, of which 12 reported collection of race day injuries or falls, using varied definitions of medical attention and time loss. Six HRAs did not have a definition for a jockey injury, and eight HRAs had no parameters for describing injury severity. Race day exposure was collected by two HRAs. Results were commonly presented by HRAs as the number of injuries (n = 9/15) or proportion of injured jockeys (n = 6/15). The lack of a designated role for collection, collation and reporting of data was the main barrier for injury surveillance. Twelve HRAs agreed that mandatory collection would be a strong facilitator to improving practice. Enhancement and standardization of international jockey injury surveillance is required to move forward with evidence informed prevention. Concurrent investigation of how reporting practices can be best supported within existing HRA structures is recommended.
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    The Welfare of Animals in Australian Filmed Media
    Hitchens, PL ; Booth, RH ; Stevens, K ; Murphy, A ; Jones, B ; Hemsworth, LM (MDPI, 2021-07)
    Animals play a significant role in the production of film and television in Australia and globally. Given this, regulating and monitoring their welfare on- and off-set is imperative. We therefore aim to compare Australia's state and territory-based legislation and regulation to those in the United States and the United Kingdom and assess regulations against the Five Domains Model of animal welfare. Historical examples of animal incidents in Australian film are used to illustrate potential deficiencies. We reviewed archived media for animal welfare incidents on and off production sets. We demonstrate a lack of uniformity, with 37.5% (3/8) of states and territories providing targeted Codes of Practice for animals in filmed media, and partially addressing behavioural interactions or mental state within the Five Domains Model. Three themes of welfare concerns were identified including incidents on-set, incidents off-set, and effects of portrayal on perception or ownership of specific species. This highlights the need for standardised national legislation and improved monitoring and regulation. Further research should quantify the number of animals used in productions, describe the type and duration of the work the animals undertake, investigate the frequency of animal welfare incidents, and explore alternative methods to the use of live animals in film and television.
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    Microstructural properties of the proximal sesamoid bones of Thoroughbred racehorses in training
    Ayodele, BA ; Hitchens, PL ; Wong, ASM ; Mackie, EJ ; Whitton, RC (WILEY, 2021-11)
    BACKGROUND: Proximal sesamoid bone fractures are common catastrophic injuries in racehorses. Understanding the response of proximal sesamoid bones to race training can inform fracture prevention strategies. OBJECTIVES: To describe proximal sesamoid bone microstructure of racehorses and to investigate the associations between microstructure and racing histories. STUDY DESIGN: Cross-sectional. METHODS: Proximal sesamoid bones from 63 Thoroughbred racehorses were imaged using micro-computed tomography. Bone volume fraction (BVTV) and bone material density (BMD) of the whole bone and four regions (apical, midbody dorsal, midbody palmar and basilar) were determined. Generalised linear regression models were used to identify the associations between bone parameters and race histories of the horses. RESULTS: The mean sesamoid BVTV was 0.79 ± 0.08 and BMD was 806.02 ± 24.66 mg HA/ccm. BVTV was greater in medial sesamoids compared with lateral sesamoids (0.80 ± 0.07 vs 0.79 ± 0.08; P < .001) predominantly due to differences in the apical region (medial-0.76 ± 0.08 vs lateral-0.72 ± 0.07; P < .001). BVTV in the midbody dorsal region (0.86 ± 0.06) was greater than other regions (midbody palmar-0.79 ± 0.07, basilar-0.78 ± 0.06 and apical-0.74 ± 0.08; P < .001). BVTV was greater in sesamoids with more microcracks on their articular surface (Coef. 0.005; 95% CI 0.001, 0.009; P = .01), greater extent of bone resorption on their abaxial surface (Grade 2-0.82 ± 0.05 vs Grade 1-0.80 ± 0.05 or Grade 0-0.79 ± 0.06; P = .006), in horses with a low (0.82 ± 0.07) or mid handicap rating (0.78 ± 0.08) compared with high rating (0.76 ± 0.07; P < .001), in 2- to 5-year-old horses (0.81 ± 0.07) compared with younger (0.68 ± 0.08) or older horses (0.77 ± 0.08; P < .001) and in horses that commenced their racing career at less than 4 years of age (0.79 ± 0.08 vs 0.77 ± 0.77; P < .001). BMD was greater in the midbody dorsal (828.6 ± 19.6 mg HA/ccm) compared with other regions (apical-805.8 ± 21.8, midbody palmar-804.7 ± 18.4 and basilar-785.0 ± 17.1; P < .001), in horses with a handicap rating (low-812.1 ± 20.0, mid-821.8 ± 21.3 and high-814.6 ± 19.4) compared with those with no rating (791.08 ± 24.4, P < .001), in females (806.7 ± 22.0) and geldings (812.2 ± 22.4) compared with entires (792.7 ± 26.2; P = .02) and in older horses (<2-year-old-763.7 ± 24.8 vs 2- to 5-year-old-802.7 ± 23.4, and 6- to 12-year-old-817.8 ± 20.0; P = .002). MAIN LIMITATIONS: Data were cross-sectional. CONCLUSIONS: Densification of the proximal sesamoid bones is associated with the commencement of racing in younger horses and the presence of bone fatigue-related pathology. Lower sesamoid BVTV was associated with longevity and better performance.
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    Variation in GPS and accelerometer recorded velocity and stride parameters of galloping Thoroughbred horses
    Morrice-West, AV ; Hitchens, PL ; Walmsley, EA ; Stevenson, MA ; Wong, ASM ; Whitton, RC (WILEY, 2021-09)
    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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    Associations between the radiographic appearance of vascular channels in proximal sesamoid bones, their microstructural characteristics and past racing performance in Thoroughbreds
    Lloyd, KA ; Ayodele, BA ; Hitchens, PL ; Beck, C ; Mackie, EJ ; Whitton, RC (WILEY, 2020-09)
    BACKGROUND: Abnormalities in vascular channel appearance within the proximal sesamoid bone (PSB) are the most common findings in Thoroughbred yearling presale radiographs and are often evaluated on radiographs of adult racehorses. Despite this, their pathogenesis and clinical significance are poorly understood, and associations with racing performance are inconsistent. OBJECTIVES: To determine microstructural characteristics of the PSBs associated with the radiographic appearance of vascular channels using microcomputed tomography (µCT) and to determine associations with past racing performance in mature horses. STUDY DESIGN: Cross-sectional. METHODS: One pair of PSBs were isolated from a forelimb of 59 Thoroughbred racehorses undergoing post-mortem examination. Each PSB (n = 118) was radiographed, assigned a vascular channel grade using previously published and novel grading systems, then imaged using µCT. Associations between radiographic, µCT and performance variables were investigated with uni- and multivariable generalised linear models. RESULTS: All PSBs had at least one vascular channel (mean 3.6 ± 0.89) observed on µCT originating from the abaxial border, yet in only 63.6% (75/118) were channels observed radiographically. Proximal sesamoid bones with a higher bone volume fraction (odds ratio [OR] 1.08; 95% confidence interval [CI] 1.01-1.15; P = .03) and wider channel diameter (mm) on µCT (OR 20.67; 95% CI 3.29-130.00; P = .001) were more likely to have vascular channels identified on radiographs. Greater radiographic channel number (OR 0.96; 95% CI 0.92-1.00; P = .04) and channel diameter (mm; OR 0.96; 95% CI 0.92-1.00; P = .04) were associated with fewer career placings. MAIN LIMITATIONS: Radiographs of isolated bones avoided the normal superimposition of tissue encountered in the live horse. CONCLUSIONS: The ability to identify vascular channels radiographically indicates widening of channels and densification of the PSB. More radiographic channels and greater channel diameter were associated with similar or poorer measures of past performance, suggesting that these changes are not desirable.
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    Global shifts in mammalian population trends reveal key predictors of virus spillover risk
    Johnson, CK ; Hitchens, PL ; Pandit, PS ; Rushmore, J ; Evans, TS ; Young, CCW ; Doyle, MM (ROYAL SOC, 2020-04-08)
    Emerging infectious diseases in humans are frequently caused by pathogens originating from animal hosts, and zoonotic disease outbreaks present a major challenge to global health. To investigate drivers of virus spillover, we evaluated the number of viruses mammalian species have shared with humans. We discovered that the number of zoonotic viruses detected in mammalian species scales positively with global species abundance, suggesting that virus transmission risk has been highest from animal species that have increased in abundance and even expanded their range by adapting to human-dominated landscapes. Domesticated species, primates and bats were identified as having more zoonotic viruses than other species. Among threatened wildlife species, those with population reductions owing to exploitation and loss of habitat shared more viruses with humans. Exploitation of wildlife through hunting and trade facilitates close contact between wildlife and humans, and our findings provide further evidence that exploitation, as well as anthropogenic activities that have caused losses in wildlife habitat quality, have increased opportunities for animal-human interactions and facilitated zoonotic disease transmission. Our study provides new evidence for assessing spillover risk from mammalian species and highlights convergent processes whereby the causes of wildlife population declines have facilitated the transmission of animal viruses to humans.
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    Participation of Victorian Thoroughbreds in the racing industry: a whole-of-population benchmark
    Flash, ML ; Crabb, HK ; Hitchens, PL ; Firestone, SM ; Stevenson, MA ; Gilkerson, JR (Wiley Online Library, 2021)
    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.