Descriptive epidemiology of African horse sickness in Zimbabwe

A study of the prevalence of African horse sickness in horses was conducted, using records from two private equine practices in Harare for the period 1998–2004. Results indicated a higher prevalence of the disease in horses in Zimbabwe in the late rainy season (March – May). Age of the horse was found to be a significant risk factor, with foals or yearlings appearing to be 1.80 times more likely to contract the disease compared with horses older than two years. The case fatality rate in foals or yearlings was also higher than in older age groups, but this difference was not significant. The vaccination status was an important risk factor, with vaccinated horses 0.12 times less likely to die from the disease compared with unvaccinated horses. Young, unvaccinated horses therefore seem to be the most susceptible to the disease and have greater chances of fatality. This study highlights the importance of adequately protecting horses against African horse sickness by providing immunisation through vaccination and discusses the need to review current vaccination strategies being practiced in Zimbabwe

A cross sectional survey of international horse-racing authorities on injury data collection and reporting practices for professional jockeys

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

The sero-prevalence and sero-incidence of African horse sickness and equine encephalosis in selected horse and donkey populations in Zimbabwe

Sentinel herds and samples submitted by private equine practitioners were used to determine the sero-prevalence and sero-incidence of African horse sickness virus (AHSV) and equine encephalosis virus (EEV) in horse and donkey populations in the Highveld region of Zimbabwe. The sero-prevalence and sero-incidence of antibodies against these viruses were determined using the competitive enzyme-linked immunosorbent assay (ELISA) for the detection of serum antibodies. In donkeys, the median sero-prevalence of AHSV antibodies, across the three rainy seasons under study, was 75% (inter quartile range [IQR] 67–83), with a seasonal median sero-incidence of 45% (IQR 40–63). In horses, the median sero-prevalence of EEV antibodies was 63% (IQR 21–73), with a median seasonal sero-incidence of 10.5% (IQR 10–14), while in donkeys the median sero-prevalence of EEV antibodies was 80% (IQR 67–90), with a median seasonal sero-incidence of 50% (IQR 40–60). This study highlighted the significant levels of exposure of donkeys to AHSV and horses and donkeys to EEV in Zimbabwe despite equine encephalosis remaining unreported by Zimbabwean veterinarians to date. Most seroconversions in sentinel herd animals to AHSV and EEV occurred towards the end of the rainy season in March, April and May corresponding to the time of the year when the Culicoides vectors are in high abundance. In order to determine the clinical significance of these infections, blood and spleen samples, submitted by private equine veterinary practitioners over a 5-year period, from horses showing characteristic clinical signs of African horse sickness were tested for the presence of viral antigen using the antigen capture ELISA. The median sero-prevalence of AHSV antigen in horses recorded from these samples was 38% (IQR 33–88). The predominant AHSV antigen from these samples was serotype 7 (33%) followed by serotype 2 (26%) and serotypes 4 and 8 (16% each). African horse sickness virus serotypes 3 and 9, identified in this study, had not been previously reported in Zimbabwe.The Biomedical Research and Training Institute and the Wellcome Trust.http://www.ojvr.orgam2017Equine Research Centr

The occurrence of Culicoides species, the vectors of arboviruses, at selected trap sites in Zimbabwe

A study of the distribution of Culicoides species was conducted by establishing 12 light trap sites over five rainy seasons between 1998 and 2003 covering all the geo-climatic natural regions of Zimbabwe. In total, 279 919 specimens of Culicoides were trapped over a total of 163 trapping nights. The highest median counts of Culicoides per trapping night were recorded in natural region III, which has climatic conditions conducive to the successful development of the larvae. Culicoides imicola, the major vector of bluetongue and African horse sickness viruses in Africa, was found to be the most abundant species (80.4%), followed by Culicoides enderleini (5.9%) and Culicoides milnei (5.2%). This study identified 10 species of Culicoides that had not been previously described in Zimbabwe, including Culicoides loxodontis and Culicoides miombo, which are members of the C. imicola complex. A total of 23 994 Culicoides midges were collected from five trap sites in Harare, Zimbabwe, with the dominant species, C. imicola, representing 91.6% of the total collection. Seventeen arboviruses were isolated from these midges, 15 of which were bluetongue virus. The predominant bluetongue virus serotype was serotype 11, followed by serotypes 1, 8, 12 and 15. Bluetongue virus serotypes 1, 2, 8, 10, 12, 15, 16 and 18, detected in this study, had not been previously reported in Zimbabwe.http://www.ojvr.org/am201

Epidemiological studies of early exercise and measures of training and racing performance in thoroughbred racehorses : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Epidemiology, Massey University, Palmerston North, New Zealand

Links to published versions of articles: Bolwell, C.F., Rogers, C.W., Firth, E.C. & French, N.P. (2010a). Management and exercise of Thoroughbred yearlings during preparation for yearling sales in North Island of New Zealand. Proceedings of the New Zealand Society of Animal Production, 70, 157-161. Retrieved from http://nzsap.org.nz. Bolwell, C.F., Rogers, C.W., Firth, E.C. & French, N.P. (2010b). Management and exercise of Thoroughbred yearlings during preparation for yearling sales. Proceedings of the 18th International Conference of Racing Analysts and Veterinarians Queenstown, New Zealand. Bolwell, C.F., Rogers, C.W., Firth, E.C. & French, N.P. (2010c). Identification of three distinct sub-populations of 2-year-old racehorses in training. Proceedings of the 18th International Conference of Racing Analysts and Veterinarians Queenstown, New Zealand. Bolwell, C.F., Rogers, C.W., French, N.P. & Firth, E.C. (in press). Risk factors for interruptions to training occurring before the first trial start of 2-year-old Thoroughbred racehorses. The New Zealand Veterinary Journal. Bolwell, C.F., Rogers, C.W., French, N.P. & Firth, E.C. (2011a). Exercise in Thoroughbred yearlings during sales preparation: A cohort study. Equine Veterinary Journal, 44(1), 20-24. doi:10.1111/j.2042-3306.2011.00370.x. Bolwell, C.F., Rogers, C.W., French, N.P. and Firth, E.C. (in press). Associations between yearling exercise and interruptions to race training in Thoroughbred racehorses. American Journal of Veterinary Research. Bolwell, C.F., Rogers, C.W., French, N.P. and Firth, E.C. (2011b) The effect of interruptions during training on the time to the first trial and race start in Thoroughbred racehorses. Manuscript submitted.for publication.This thesis includes a series of epidemiological studies conducted to quantify the exercise regimens of Thoroughbred yearlings during their sales preparation and 2- and 3-year-old race training. Additionally, this thesis aims to establish if there are associations between the exercise regimens and training and racing performance at two years of age. Cross-sectional and cohort studies quantified the components of the exercise regimens used during sales preparation on stud farms in New Zealand. Exercise was a common practice during sales preparation. The type and amount of exercise was often tailored to individual horses. Overall, exercise varied by gender, the month of preparation, and between farms indicating that the exposure to exercise during sales preparation was not the same for all horses. Survival analysis identified different horse and exercise risk factors for voluntary, involuntary, and musculoskeletal interruptions during training. Specifically, there were strong associations between increased total hand walking time and reduced chance of voluntary interruptions, and more time walking on a mechanical walker increased the risk of involuntary interruptions. Other horse and training factors, such as trainer, gender, age at the start of training, and the distance accumulated at canter and high speed, were associated with the time to interruptions during training. Interruptions before the first trial were associated with an increased time to the first trial or race and a decreased chance of starting in a trial. Accumulating shorter distances and fewer events at high speed were both associated with a decreased chance of a trial or race start. Longer distances accumulated at high speed were associated with a decreased time to the first trial. No associations were found between the exercise accumulated during sales preparation and the time to the first trial during training. Overall, the exercise accumulated during sales preparation was associated with a measure of training performance, whilst the timing of interruptions and the accumulation of exercise during training have implications for reaching important training and racing milestones. The results of this thesis indicate that current exercise regimens could be modified to enhance the training and racing performance of Thoroughbred racehorses

Epidemiology of Musculoskeletal Injury during Racing on New Zealand Racetracks 2005–2011

The objective of the study was to determine the incidence of veterinary events that resulted in a horse failing to finish a race and identify risk factors for musculoskeletal injury (MSI) during a race. Data were obtained on Thoroughbred flat race starts in New Zealand between 1 August 2005 and 31 July 2011 (six racing seasons). Stipendiary Steward’s reports were key-word searched to identify veterinary events that prevented a horse from finishing a race. Race data were used calculate the incidence of veterinary events per 1000 horse starts and Poisson regression was used to investigate risk factors for MSI. There were 188,616 race starts and 177 reported veterinary events. The incidence of MSI on race day was 0.72 per 1000 starts, whilst the incidence of respiratory events was 0.21 per 1000 starts. The rate of MSI was significantly lower on ‘dead’ and ‘slow’ tracks compared with ‘good’ tracks and significantly greater in longer races (≥1671 m) compared with races of ≤1200 m. The rate of MSI during flat races in New Zealand appears lower than that reported worldwide, which may be due to the management and training of horses in New Zealand or differences in case definitions used in comparable studies

Proactive Management of the Equine Athlete

Across many equestrian disciplines the median competition career of a horse is relatively short. One of the major reasons for short career length is musculoskeletal injury and a consistent variable is the trainer effect. There are significant opportunities within equestrian sport for a holistic approach to horse health to attenuate musculoskeletal injury. Proactive integration of care by health professionals could provide a mechanism to attenuate injury risk and the trainer effect. However, the limited data available on current exercise regimens for sport horses restricts interpretation of how management and exercise volume could be modified to reduce injury risk. Early exercise in the juvenile horse (i.e., pre weaning) has a positive effect on stimulating the musculoskeletal system and primes the horse for an athletic career. The early introduction to sport competition has also been identified to have a positive effect on career length. These data indicate that management systems reflecting the cursorial evolution of the horse may aid in attenuating loss from sport due to musculoskeletal injury

Proactive Management of the Equine Athlete

Across many equestrian disciplines the median competition career of a horse is relatively short. One of the major reasons for short career length is musculoskeletal injury and a consistent variable is the trainer effect. There are significant opportunities within equestrian sport for a holistic approach to horse health to attenuate musculoskeletal injury. Proactive integration of care by health professionals could provide a mechanism to attenuate injury risk and the trainer effect. However, the limited data available on current exercise regimens for sport horses restricts interpretation of how management and exercise volume could be modified to reduce injury risk. Early exercise in the juvenile horse (i.e., pre weaning) has a positive effect on stimulating the musculoskeletal system and primes the horse for an athletic career. The early introduction to sport competition has also been identified to have a positive effect on career length. These data indicate that management systems reflecting the cursorial evolution of the horse may aid in attenuating loss from sport due to musculoskeletal injury

Veterinary and Equine Science Students’ Interpretation of Horse Behaviour

Many veterinary and undergraduate equine science students have little previous horse handling experience and a poor understanding of horse behaviour; yet horses are one of the most unsafe animals with which veterinary students must work. It is essential for veterinary and equine students to learn how to interpret horse behaviour in order to understand demeanour and levels of arousal, and to optimise their own safety and the horses’ welfare. The study utilised a qualitative research approach to investigate veterinary science and veterinary technology and undergraduate equine science students’ interpretation of expressive behaviours shown by horses. The students (N = 127) were shown six short video clips and asked to select the most applicable terms, from a pre-determined list, to describe the behavioural expression of each individual horse. A wide variation of terms were selected by students and in some situations of distress, or situations that may be dangerous or lead to compromised welfare, apparently contradictory terms were also selected (happy or playful) by students with less experience with horses. Future studies should consider the use of Qualitative Behavioural Analysis (QBA) and free-choice profiling to investigate the range of terms used by students to describe the expressive demeanour and arousal levels of horses