Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in hurdle starts in the UK (2001-2009)

Prognostic value of power doppler ultrasonography for equine superficial digital flexor tendon injury in thoroughbred racehorses

The potential value of hypervascularity detected with power Doppler ultrasonography (PDU) within equine superficial digital flexor tendon (SDFT) as a prognostic factor of SDFT injury is not clear. The purpose of this study was to test the hypothesis that hypervascularity within SDFT is one of the risk factors for subsequent severe SDFT injury and to evaluate the prognostic value. A prospective cohort study of 97 Thoroughbred racehorses without any clinical signs of SDFT injury was conducted. Six variables of age, body weight, sex, the cross-sectional area of SDFT, PDU signal within SDFT and experience of steeplechase were assessed for the possibility of risk factors of subsequent SDFT injury in follow-up period of 1 year. Multivariable logistic regression analyses were used for assessment of the odds ratios (ORs) and 95 % confidence intervals (CIs) of SDFT injury. Multivariable logistic regression analysis revealed that the PDU signal within SDFT was a risk factor for the development of SDFT injury in follow-up period (P = 0.017). The adjusted OR of SDFT injury was significantly higher in PDU positive group than in PDU negative group (OR 3.17, 95 % CIs 1.20-8.35). Although further studies are required, these results would be useful for early detection and/or prevention of development for clinical severe SDFT injury.

Treatment of racehorse superficial digital flexor tendonitis: A comparison of stem cell treatments to controlled exercise rehabilitation in 213 cases

BACKGROUND

Overstrain of the superficial digital flexor tendon (SDFT) is a common Thoroughbred racehorse limb injury requiring treatment.

OBJECTIVES

To determine whether treatment of SDFT lesions in flat Thoroughbred racehorses with autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) or allogenic adipose-derived mesenchymal stem cells (A-MSCs) is associated with improved likelihood of returning to racing, when compared to racehorses managed with a controlled exercise rehabilitation program (CERP) alone.

STUDY DESIGN

Retrospective cohort study combining clinical treatment records with race records.

METHODS

A total of 213 Thoroughbred racehorses were identified. All were prescribed the same 12-month CERP and 66 also received intralesional BM-MSC and 17 A-MSC treatment. Follow-up was a minimum of 2 years after return to full race training. Multivariable logistic regression models were used to investigate associations between the treatments and the likelihood of returning to racing and completing five or more (C5+) races post-injury.

RESULTS

Compared to CERP alone, BM-MSC treatment was associated with increased odds of returning to racing (OR 3.19; 95% CI 1.55-6.81) and C5+ races post-injury (OR 2.64; 95% CI 1.32-5.33). Older age and increasing lesion length were associated with a reduced likelihood of returning to racing. Male sex and increased number of pre-injury starts were associated with increased odds of returning to racing. There was no observed increased likelihood of return to racing or C5+ races associated with treatment with A-MSCs compared to CERP alone.

MAIN LIMITATIONS

Due to the retrospective nature of the study it was not possible to ascertain how strictly the CERP was followed. Due to the novelty of the method, the A-MSC treatment group included a limited number of horses.

CONCLUSIONS

In the study population, intralesional BM-MSC treatment was significantly associated with an increased likelihood of returning to racing and C5+ races post-injury compared to CERP alone. Intralesional A-MSC showed no significant association between treatment and the two investigated outcomes.

Defining the Profile: Characterizing Cytokines in Tendon Injury to Improve Clinical Therapy

Cytokine manipulation has been widely used to bolster innate healing mechanisms in an array of modern therapeutics. While other anatomical locations have a more definitive analysis of cytokine data, the tendon presents unique challenges to detection that make a complete portrayal of cytokine involvement during injury unattainable thus far. Without this knowledge, the advancement of tendon healing modalities is limited. In this review, we discuss what is known of the cytokine profile within the injured tendinous environment and the unique obstacles facing cytokine detection in the tendon while proposing possible solutions to these challenges. IL-1β, TNF-α, and IL-6 in particular have been identified as key cytokines for initiating tendon healing, but their function and temporal expression are still not well understood. Methods used for cytokine evaluation in the tendon including cell culture, tissue biopsy, and microdialysis have their strengths and limitations, but new methods and approaches are needed to further this research. We conclude that future study design for cytokine detection in the injured tendon should meet set criteria to achieve definitive characterization of cytokine expression to guide future therapeutics.

Factors associated with completion of Fédération Équestre Internationale endurance rides (2012-2019): Modelling success to promote welfare-oriented decisions in the equestrian sport of endurance

Endurance riding is a popular equestrian sport organised at the international level by the Fédération Équestre Internationale (FEI). The sport involves prolonged exercise at speed over significant distances, which puts a substantial load on equine athletes' musculoskeletal systems and metabolism and contributes to the risk of injuries and other veterinary problems. The FEI employs a system of in-ride veterinary inspections aimed at early detection of such problems and elimination of horses unfit to continue in the ride. To date, risk factors for elimination due to irregular gait or metabolic problems have been the primary focus of scientific enquiry. The present study is the first large-scale multivariable study to report factors associated with the positive outcome of endurance rides - their successful completion. This retrospective observational cohort study used data from the FEI's Global Endurance Database. The study cohort included 74,629 starts made by 21,346 unique horses in one-day international-level competitions held worldwide between July 2012 and December 2019. Forty-one potential factors identified based on previous studies and a priori hypotheses were considered in the analysis. Univariable and multivariable logistic regression analyses were performed to investigate associations between ride completion and predictor variables and their interactions. The study identified 19 factors and four interactions associated with an increased or decreased likelihood of successful ride completion. High competition frequency (fewer days over mandatory out of competition period; Wald χ² 71.35, P-value <0.0001), fast riding speed (236.57, <0.0001), upward changes in competition level and riding speed between two successive rides (103.59, <0.0001 and 87.60, <0.0001) were associated with a decrease in the likelihood of ride completion. These factors can be effectively regulated by appropriate rules and considered by athletes when planning competition schedules, preparing ride strategies, or indeed during the ride itself. Other identified factors, including horse and rider age, sex, completions and eliminations history, contribute to an estimate of the likelihood that a particular combination completes a ride and thus can aid veterinarians at veterinary inspections as additional inputs supporting their decision-making when assessing horses' fitness to continue in the competition. The study's main limitation is an absence of data on national-level rides. Such data and data on training and veterinary histories remain difficult to access and were unavailable for the analysis. The present study's results demonstrate that shifting the focus to modelling the positive outcome is a valuable approach offering evidence-based recommendations for good horsemanship, better-informed veterinary inspections, and welfare-oriented rules.

Association between the administration of phenylbutazone prior to racing and musculoskeletal and fatal injuries in Thoroughbred racehorses in Argentina

OBJECTIVE

To examine the association between prerace administration of phenylbutazone and the risk of musculoskeletal injury (MSI) and fatal injury in Thoroughbred racehorses that raced between 2006 and 2015 at 2 of the 4 official racetracks in Argentina.

SAMPLE

Data from racetrack databases and veterinary reports on 283,193 race starts.

PROCEDURES

Data were collected relating to race performance and injury outcomes for starts at these tracks. The incidence of MSI and fatal injury was calculated for each year, stratified by the declared prerace administration of phenylbutazone. Univariable logistic regression, followed by multivariable logistic regression, was used to identify significant risk factors for both MSI and fatal injury.

RESULTS

Analyses identified associations between the declared prerace administration of phenylbutazone and the risk of MSI and fatal injury during racing. Horses with declared prerace phenylbutazone administration had greater odds of MSI (OR, 1.45 [95% CI, 1.03 to 2.04]) and fatal injury (OR, 1.59 [95% CI, 1.1 to 2.27]) than did horses racing without prerace phenylbutazone administration. These associations remained significant when other risk factors were accounted for in both multivariable models.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested an association between the prerace administration of phenylbutazone and the risk of MSI and fatal injury in Thoroughbred racehorses during racing. Although these results did not imply a direct causal relationship between prerace phenylbutazone administration and injury, they may be considered in the development of more conservative medication policies to optimize racehorse welfare in North and Latin America.

Appraising the Welfare of Thoroughbred Racehorses in Training in Queensland, Australia: The Incidence, Risk Factors and Outcomes for Horses after Retirement from Racing

There is international public concern regarding retirement of racehorses, including the reason for retirement and the outcome for horses after racing. However, there are currently no prospective studies investigating these factors. A recent independent inquiry in Queensland, Australia, highlighted that the true outcomes for horses after retirement from racing are largely unknown. Furthermore, there are currently no measures to monitor the outcome for racehorses and their welfare once they have left the care of the trainer. This study investigated these gaps in knowledge through a weekly survey conducted over a 13-month period. We aimed to evaluate: (1) the incidence of retirement, (2) the reasons and risk factors for retirement and (3) the medium-term (greater than 6 months) outcomes for horses after retirement. Data were collected through personal structured weekly interviews with participating trainers and analysed using negative binomial and logistic regression. There was a low incidence of retirements, namely 0.4% of horses in training per week. The season and training track did not affect the incidence of retirement. Musculoskeletal injuries were the most common reason for retirement (40/110 horses, 36%). Involuntary retirements accounted for 56/100 (51%) of retirements, whereby musculoskeletal injuries, respiratory or cardiac conditions and behavioural problems prevented the horse from racing The odds of voluntary retirement, whereby the horse was retired due to racing form or impending injury, increased with each additional race start (OR 1.05; p = 0.01) and start/year of racing (OR 1.21; p = 0.03) but decreased with increasing percentage of first, second and third places (OR 0.94; p < 0.001). Medium-term follow-up (median 14 months, IQR 11, 18, range 8-21) revealed that most horses (108/110; 98%) were repurposed after retirement, almost half as performance horses (50/110; 46%). Horses that voluntarily retired had 2.28 times the odds of being repurposed as performance horses than those retired involuntarily (p = 0.03). Whether retirement was voluntary or involuntary did not influence whether horses were used for breeding or pleasure. The primary limitation of this study is that our results reflect retirement in racehorses in South East Queensland, Australia, and may not be globally applicable. Furthermore, we were unable to monitor the long-term outcome and welfare of horses in their new careers. It is vital that the industry is focused on understanding the risks for voluntary rather than involuntary retirement and optimising the long-term repurposing of horses. There is a need for traceability and accountability for these horses to ensure that their welfare is maintained in their new careers.

Faults in international showjumping are not random

Performance analysis (PA) involves the systematic observation and analysis of factors identified to enhance performance to improve athlete decision-making in a specific sport. PA is commonplace in human sports, yet despite potential advantages, its application remains limited in equestrianism. This study aimed to evaluate if factors anecdotally associated with performance in elite showjumping influenced competitive success. 250 combinations attempting 3,052 jumping-efforts across 2nd round European Fédération Equestre Internationale Nations Cup 2017 competition were analysed. Types of fault (e.g. pole down, refusal, etc.) were recorded as well as characteristics of the jump (e.g. jump type, approach angle). Combinations jumped clear at the majority of attempts (93.6; n=2,857) with faults only occurring at 6.4% of jumps (n=195). The most common faults were knock-downs (5.5%), time penalties (0.8%), faults at water jumps (0.3%) and refusal (0.2%). Faults were distributed across all fence types, however, were more common at upright fences (49%) and within combination fences (41%). A linear relationship was found between jumping-effort number and number of fences knocked-down (r=0.7; P<0.001). There were 2.8 times more knock-downs for the second half of the course (efforts 9-15) compared with jumping-efforts 1-7 (P<0.05). Faults were 4 times more likely at jumping-efforts 3, 4, 5 and 8 in the first half of the course (P<0.03) which increased to being 9 times more likely in the 2nd half of the courses (jumping-efforts 9, 10, 11, 12, 13 and 14; P<0.006). A straight approach to a jumping-effort reduced the chance of faults by 48% (P<0.0001) compared to a non-straight approach. These preliminary results suggest faults are not randomly distributed in elite showjumping and that patterns exist within fault accumulation demonstrating that the application of PA techniques in equestrian sport could lead to a performance advantage.

Equine musculoskeletal development and performance: impact of the production system and early training

The welfare debate around horse racing appears to be focussed on musculoskeletal injury and the racing of 2-year-olds. Much of this debate appears contrary to the evolutionary history of the horse as a cursorial animal and the capability of the equine musculoskeletal system to respond to the demands of race training. Epidemiological studies have reported that 2-year-old racehorses have a longer time period from entering training to the first race and a greater number of lost training days than older horses. However, this is, in part, due to the time taken to learn to train and the impact of dorsal metacarpal disease, which is due to loading of naïve as opposed to immature tissue. Across several racing jurisdictions and codes, it has been demonstrated that horses that train and race as 2-year-olds have longer, more successful, careers than those that start racing later in life. This positive trend has also been observed with horses starting in equestrian sport at an early age. The literature on the growth and development of the horse indicates that the musculoskeletal system is primed for activity and loading from an early age. Additional exercise for the young horse has a positive rather the negative effect, with many tissues having a sensitive period for ‘priming’ when the horse is a juvenile. This implies that under many modern management systems, the challenge to horse welfare is not ‘too much exercise too soon’ but ‘too little too late’. The current limitation in our understanding is the lack of knowledge of what is the correct exercise dose to optimise the musculoskeletal system. Modern management systems invariably provide too little exercise, but is the exercise data from feral horses the ‘gold standard’, or more a reflection of what the horse is capable of if resources such as food and water are limited? Further research is required to refine our understanding of the optimal exercise levels required and development of greater precision in identifying the sensitive periods for priming the musculoskeletal system.

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racing horses in Japan

Thoroughbred racehorses are commonly affected with superficial digital flexor (SDF) tendinopathy. This study aimed to identify risk factors for SDF tendinopathy in racing horses. The authors selected racehorses (n=292) with SDF tendinopathy from the medical records of a racetrack. As a risk factor associated with track-related variables, the SDF tendinopathy odds ratio (OR) was significantly high for a sloppy track surface compared with a standard track surface. Regarding risk factors associated with race-related variables, the SDF tendinopathy OR was significantly high in the following cases: when the order of arrival was worse than or equal to the 10th place; when the racehorses started to run a short race and when the racehorses' favourites were worse than or equal to the 8th place. Regarding risk factors associated with racehorse-related variables, the body weight of racehorses with SDF tendinopathy was significantly heavier than that of control horses. When there was a decrease in body weight since previous racing, the SDF tendinopathy OR was significantly high. Regarding risk factors associated with race career-related variables, when the charge in the race distance was short, the SDF tendinopathy OR was significantly high. As a countermeasure to prevent SDF tendinopathy, a sloppy track surface should be avoided during the race by guiding the horse toward to more solid track surface. Selecting long-distance races with slow speed, if possible, could reduce the risk of SDF tendinopathy.

Ultrasonographic-based predictive factors influencing successful return to racing after superficial digital flexor tendon injuries in flat racehorses: A retrospective cohort study in 469 Thoroughbred racehorses in Hong Kong

BACKGROUND

Superficial digital flexor tendon (SDFT) injury is an important health and welfare concern in racehorses. It is generally diagnosed with ultrasonography, but predictive ultrasonographic features have not been reported.

OBJECTIVES

To determine ultrasonographic features of forelimb SDFT injury at initial presentation in Thoroughbred racehorses that could predict a successful return to racing (completing ≥5 races).

STUDY DESIGN

Retrospective cohort study.

METHODS

Digitised ultrasonographic images of 469 horses with forelimb SDFT injuries from the Hong Kong Jockey Club (2003-2014) were evaluated, using a previously validated ultrasonographic scoring system. Six ultrasonographic parameters were evaluated (type and extent of the injury, location, echogenicity, cross-sectional area and longitudinal fibre pattern of the maximal injury zone [MIZ]), as well as horse signalment, retirement date and number of races before and after injury. Data were analysed by generalised linear regression with significance at P<0.05.

RESULTS

Cases were divided into two groups: 1) For cases of SDFT tendonitis with core lesions, cross-sectional area at the MIZ was the most significant factor determining a successful return to racing (P = 0.03). If the lesion was <50% of the total cross-sectional area, horses had 29-35% probability of successfully racing again, but if it was ≥50% this decreased to 11-16%. 2) For cases of SDFT tendonitis without a core lesion, longitudinal fibre pattern at the MIZ best predicted a successful return to racing (P = 0.002); if the affected longitudinal fibre pattern was <75% of the total, horses had 49-99% probability of successfully return to racing, but if it was ≥75% this decreased to 14%.

MAIN LIMITATIONS

Prognostic information may not be applicable to other breeds/disciplines.

CONCLUSIONS

This is the first study to describe ultrasonographic features of forelimb SDFT injuries at initial presentation that were predictive of successful return to racing. The outcomes will assist with early, evidence-based decisions on prognosis in Thoroughbred racehorses.

Ontario Racehorse Death Registry, 2003-2015: Descriptive analysis and rates of mortality

BACKGROUND

The Province of Ontario maintains a registry of racehorse deaths occurring within 60 days of a race or trial entry that provides insight into mortality rates and costs of competition.

OBJECTIVES

To characterise and quantify mortality and identify breed differences.

STUDY DESIGN

Retrospective annualised cohort study.

METHODS

The Ontario Death Registry for 2003-2015, containing 1713 cases, was audited and information on the relationship between death and official work added. Race and trial data from industry performance databases were used to determine mortality rates according to breed, year, age, sex and circumstances of death.

RESULTS

Breed differences in mortality rate and individual risk were found. Thoroughbreds (Tb) had the greatest exercise-associated mortality (EAM) rate and risk by all measures (2.27 deaths/1000 race starts, 0.95-1.0% annual individual risk), followed by Quarter horses (Qh, 1.49, 0.60-0.69%). Rate and risk were lowest for Standardbreds (Sb, 0.28, 0.23-0.24%). Nonexercise annual individual risk was highest for the Sb (0.45%, vs. Tb 0.33%, and Qh 0.32%). Pattern and type of EAM mirrored the characteristics of competitive activity in each industry, with high Tb and Qh mortality being associated with exercise and involving musculoskeletal injuries, dying suddenly and accidents. Low Sb EAM reflected the more extensive nature of training preparation and racing for this breed.

MAIN LIMITATIONS

Available data provided no information on morbidity, mortality beyond the 60-day horizon or for horses not racing. Numbers for the Qh were low.

CONCLUSIONS

Race-intensity exercise is clearly hazardous for horses, with hazards varying widely between breeds and showing parallels with industry cultural and management norms. Breed differences provide insights concerning strategies that could reduce mortality, while improving welfare and reducing costs of participation. For all breeds, musculoskeletal injury was the major contributing cause of mortality.

Risk factors for race-day fatality in flat racing Thoroughbreds in Great Britain (2000 to 2013)

A key focus of the racing industry is to reduce the number of race-day events where horses die suddenly or are euthanased due to catastrophic injury. The objective of this study was therefore to determine risk factors for race-day fatalities in Thoroughbred racehorses, using a cohort of all horses participating in flat racing in Great Britain between 2000 and 2013. Horse-, race- and course-level data were collected and combined with all race-day fatalities, recorded by racecourse veterinarians in a central database. Associations between exposure variables and fatality were assessed using logistic regression analyses for (1) all starts in the dataset and (2) starts made on turf surfaces only. There were 806,764 starts in total, of which 548,571 were on turf surfaces. A total of 610 fatalities were recorded; 377 (61.8%) on turf. In both regression models, increased firmness of the going, increasing racing distance, increasing average horse performance, first year of racing and wearing eye cover for the first time all increased the odds of fatality. Generally, the odds of fatality also increased with increasing horse age whereas increasing number of previous starts reduced fatality odds. In the 'all starts' model, horses racing in an auction race were at 1.46 (95% confidence interval (CI) 1.06-2.01) times the odds of fatality compared with horses not racing in this race type. In the turf starts model, horses racing in Group 1 races were at 3.19 (95% CI 1.71-5.93) times the odds of fatality compared with horses not racing in this race type. Identification of novel risk factors including wearing eye cover and race type will help to inform strategies to further reduce the rate of fatality in flat racing horses, enhancing horse and jockey welfare and safety.

Effect of track surface firmness on the development of musculoskeletal injuries in French Trotters during four months of harness race training

OBJECTIVE To evaluate the effect of track surface firmness on the development of musculoskeletal injuries in French Trotters during 4 months of race training. ANIMALS 12 healthy 3-year-old French Trotters. PROCEDURES Horses were paired on the basis of sex and body mass. Horses within each pair were randomly assigned to either a hard-track or soft-track group. The counterclockwise training protocol was the same for both groups. Surface firmness of each track was monitored throughout the training period. Radiography, ultrasonography, MRI, and scintigraphy were performed on all 4 limbs of each horse before and after 2 and 4 months of training. Lesions were described, and lesion severity was classified with a 5-point system, where 0 = no lesions and 4 = severe lesion. RESULTS 86 lesions were identified, of which 46 (53.5%) were classified as potentially clinically relevant (grade, ≥ 2). Of the 18 moderate and severe lesions, 15 were identified in horses of the hard-track group, and 10 of those were in forelimbs. Moderate to severe tendinopathy of the superficial digital flexor tendon of the forelimb developed in 3 of the 6 horses of the hard-track group but none of the horses of the soft-track group. Metatarsal condyle injuries were more frequent in horses of the hard-track group than horses of the soft-track group. Severe lesions were identified only in left limbs. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that track surface firmness is a risk factor for musculoskeletal injuries in horses trained for harness racing.

Risk factors for race-day fatality, distal limb fracture and epistaxis in Thoroughbreds racing on all-weather surfaces in Great Britain (2000 to 2013)

The incidence of race-day injuries in Great Britain (GB) is higher on all-weather (AW) surfaces than on turf. However, to date no studies have focused on identifying risk factors for injury specific to AW racing. Therefore, the objective of the current study was to determine risk factors for fatality, distal limb fracture (DLF) and episodes of epistaxis in flat racing Thoroughbreds racing on AW surfaces in GB. Data included all flat racing starts on AW surfaces (n=258,193) and race-day veterinary events recorded between 2000 and 2013. Information on additional course-level variables was gathered during face-to-face interviews with racecourse clerks. Horse-, race- and course-level risk factors for each outcome were assessed using mixed-effects multivariable logistic regression including horse as a random effect. A classification tree method was used to identify potential interaction terms for inclusion in the models. During the study period, there were 233 fatalities resulting in a fatality incidence of 0.90 per 1000 starts; 245 DLF with a resultant DLF incidence of 0.95 per 1000 starts and 410 episodes of epistaxis resulting in an epistaxis incidence of 1.59 per 1000 starts. Risk factors varied for each outcome, although some factors were similar across models including the going, racing intensity, horse age, age at first race start, horse and trainer performance variables. Generally, older horses and those that had started racing at an older age were at higher risk of an adverse outcome, albeit with an interaction between the two variables in the fatality model. Faster going increased the odds of epistaxis and DLF but not fatality. Increasing race distance increased the odds of fatality but reduced the odds of epistaxis. Epistaxis was associated with type of AW surface (Fibresand versus Polytrack^®), but DLF and fatality were not. This study provides further evidence of the association between the risk of race-day injuries and fatalities and current age, age at first start, race distance, going and horse performance. These findings provide the racing industry with information to develop strategies to reduce the occurrence of race-day events on AW surfaces.

Description of veterinary events and risk factors for fatality in National Hunt flat racing Thoroughbreds in Great Britain (2000-2013)

BACKGROUND

No large-scale studies have described veterinary events occurring in National Hunt (NH) flat racing or investigated risk factors for fatality in this race type.

OBJECTIVES

To describe injuries and conditions requiring veterinary attendance on race day and to determine risk factors for racehorse fatality in NH flat racing in Great Britain.

STUDY DESIGN

Retrospective cohort study (2000-2013).

METHODS

Information from all NH flat races held over the study period, including horse, race and veterinary event report details, was combined. Veterinary events were described by type and anatomical structure(s) affected. Incidence per 1000 starts were calculated for all veterinary events and by event group, and stratified by certain horse- and race-level variables. Risk factors for fatality were determined using multivariable logistic regression modelling.

RESULTS

Over the 14-year study period, 544 veterinary events were recorded, providing an overall incidence of 13.0 events per 1000 starts. The most common events were bone injuries (23.5%) and tendon or ligament injuries (16.4%). A fatal outcome was recorded for 117 horses (21.5% of all events), resulting in an incidence of 2.9 deaths per 1000 starts. Odds of fatality were 4.33 (95% confidence interval [CI] 1.59-11.82; P = 0.02) times higher in races restricted to conditional jockeys compared to those that were not. Horses starting in their first race experienced 1.44 (95% CI 1.00-2.08; P = 0.05) times the odds of death compared to those that had raced before.

MAIN LIMITATIONS

Classification of veterinary events frequently relied upon presumptive diagnosis.

CONCLUSIONS

This study provides a benchmark for the ongoing surveillance of veterinary events in NH flat racing. These results support the phasing out of NH flat races restricted to conditional jockeys and highlight the need for further work to establish why NH flat racing Thoroughbreds competing in their first race are at increased risk for death.

Comparison of treatment outcomes for superficial digital flexor tendonitis in National Hunt racehorses

Superficial digital flexor (SDF) tendonitis is a common injury in Thoroughbred racehorses. Injuries require prolonged rehabilitation, with unpredictable outcomes and a high incidence of re-injury. This observational case-control study aimed to compare race outcomes after commonly advocated treatments for tendon healing. Clinical and racing records were evaluated for 127 National Hunt racehorses treated between 2007 and 2011 for an SDF tendon injury. Two age- and sex-matched control horses were selected for each case horse to analyse the effect on post-injury racing outcomes of pre-injury data, lesion severity and treatment group [controlled exercise alone, bar firing, intralesional platelet-rich plasma (PRP), tendon splitting, tendon splitting combined with bar firing]. Control horses raced more often than case horses, with higher maximum racing post rating (RPRmax) and longer racing distances. Pre-injury racing performance was not associated with treatment group. Rate of return to racing was not associated with lesion severity or treatment group. Number of races, total distance raced post-injury and RPRmax were not associated with lesion severity or treatment group. Controlled exercise alone offered similar post-injury racing outcomes in National Hunt racehorses with SDF tendonitis to the other treatment options examined. Bar firing, either alone or in conjunction with tendon splitting, provided no additional benefit in rate of return to racing and race performance.

Descriptive epidemiology of veterinary events in flat racing Thoroughbreds in Great Britain (2000 to 2013)

BACKGROUND

To date, no large scale studies have reported race-day events requiring veterinary attention in British Thoroughbreds racing on the flat. Quantifying and describing common injuries and health conditions affecting racehorses will enable targeted risk factor analysis aimed at reducing their occurrence.

OBJECTIVE

To describe the type and incidence of race-day veterinary events experienced by Thoroughbred racehorses participating in flat racing in the UK.

STUDY DESIGN

Retrospective cohort study (2000 to 2013).

METHODS

Veterinary events recorded by race-day veterinarians were retrieved and linked to race start data. Race-day veterinary events were described by type, location and anatomical structure(s) affected and whether the outcome was fatal or not. Incidence per 1000 starts was calculated, both overall and by year. Stratified incidence rates were calculated for selected event categories by specific course- and horse-level variables.

RESULTS

There were 7993 events experienced by 6727 horses, with an incidence of 9.37 events per 1000 starts. Soft tissue injuries other than tendon and ligament injuries were the most commonly occurring veterinary events (24.1%), followed by gait observations (21.2%) and respiratory conditions (21.2%). In total, 13.8% of events were bone injuries. The incidence of fatality (n = 628) was 0.76 per 1000 starts. Most (485/628, 77.2%) fatal events were bone injuries, 64 were due to cardiac conditions and 54 due to tendon and ligament injuries. All-weather tracks had a higher incidence of veterinary events and fatalities than turf tracks. Firmer (turf) or faster (all-weather) going were associated with a higher incidence of all veterinary events.

MAIN LIMITATIONS

Events were based on presumptive, rather than definitive, veterinary diagnosis.

CONCLUSION

The most common events experienced by racehorses on race-day were relatively minor and not career-ending. Although more severe bone, joint, tendon and ligament injuries were less common, they had a greater impact on whether the outcome of the event was fatal.

Descriptive statistics and the pattern of horse racing in New Zealand. 2. Harness racing

The aim of the present study was to describe the pattern of pacing and trotting races and starts, including temporal trends, in Harness racing in New Zealand. Data on all race starts between 1 August 2005 and 31 July 2010 were supplied by Harness Racing New Zealand. Descriptive statistics were used to describe the data at both race and starts level, stratified by pacing and trotting races. In total, 78% of races run were pacing races and most races occurred in the Southern region. The start type varied by race, with most pacing races run with mobile starts and trotting races with standing starts. Regardless of race type most races were run on all-weather tracks and were run in the summer or autumn. There was little change in the median number of starts per horse over time and the median number of starters per trainer per year was 16 (interquartile range 7–35, max. 612) and 12 (interquartile range 5–24, max. 235) for pacing and trotting races, respectively. Differences in track surfaces, gait, region and drivers between the Standardbred and the Thoroughbred industry suggests a need for data specific to the Harness racing industry in New Zealand. This study provided baseline data on the pattern of Standardbred racing and highlighted factors unique to the Harness racing industry in New Zealand.

The role of personality in equestrian sports: an investigation

Personality has been shown to affect the way individuals think, feel and act, and could impact on the way people behave and perform in a wide variety of activities. Anecdotal evidence suggests that differences in personality exist between equestrians participating in different disciplines and at different levels, but empirical evidence is limited. This study aimed to investigate dispositional tendencies of rider cohorts, in relation to age, nationality, discipline, competitive level, breadth of involvement in different disciplines, and level of risk-seeking behaviour. An online survey was developed, collecting rider demographics relating to nationality, sex, age, competitive level and discipline. A risk scores was assigned to each discipline and an average risk rating was calculated per participant. Personality traits of extroversion, agreeableness, conscientiousness, neuroticism and intellect were measured using the Mini-International Personality Item Pool. Kruskal-Wallis analyses determined differences for personality traits between different survey categories. Univariable analysis of all factors considered informed multivariable logistic regression models to establish how factors including personality traits differed between dichotomous variables: high to low risk discipline, age groups, unaffiliated to affiliated riders and amateur to professional riders. Results showed that riders in their late teens and early twenties considered themselves less agreeable, less conscientious, but more neurotic compared to older generations (P<0.001). Competitive riders considered themselves more conscientious and extroverted than non-competitors (P<0.005). Riders participating in higher risk disciplines considered themselves less agreeable and conscientious (P<0.05). Increases in agreeableness, conscientious and decreases in neuroticism in older riders might predispose them towards a role in coaching and providing support for younger riders. Personality differences between riders of different disciplines and at different competitive levels might be used to help individuals in their choice of equestrian sport and level of involvement. In conclusion, the present study demonstrates the value of identifying personality traits across different rider cohorts.

The foot-surface interaction and its impact on musculoskeletal adaptation and injury risk in the horse

The equine limb has evolved for efficient locomotion and high-speed performance, with adaptations of bone, tendon and muscle. However, the system lacks the ability seen in some species to dynamically adapt to different circumstances. The mechanical interaction of the limb and the ground is influenced by internal and external factors including fore-hind mass distribution, lead limb, moving on a curve, shoeing and surface properties. It is unclear which of the components of limb loading have the largest effect on injury and performance but peak load, impact and vibration all play a role. Factors related to the foot-ground interface that limit performance are poorly understood. Peak performance varies vastly between disciplines but at high speeds such as racing and polo, force and grip are key limits to performance.

Polo pony injuries: player-owner reported risk, perception, mitigation and risk factors

REASONS FOR PERFORMING STUDY

Polo, one of the world's oldest sports, is unique in merging human skill and balance with animal agility and performance in a contact sport. These modern-day 'centaurs' offer medical, dental and veterinary scientists an unrivalled, if quirky, opportunity to collaborate. Collection of epidemiological data on injuries to UK polo riders and ponies is the first step.

OBJECTIVES

To measure the reported risk and risk factors for injuries to UK polo ponies, their perception and mitigation by player-owners.

STUDY DESIGN

A retrospective cohort design and telephone interviews were used.

METHODS

Data on equine injuries, preseason training and risk perception were collected from a random sample of player-owners using a structured questionnaire. Injuries were defined as requiring veterinary treatment. Frequencies were represented as percentages and 95% confidence intervals (CIs). Risk factors for injuries were identified by univariable and multivariable analyses.

RESULTS

The cumulative incidence of player-owner-reported injury was 10.6% (95% CI 8.4-12.7). Tendon injuries were most common (4.3%; 95% CI 2.9-5.7), followed by wounds and splints. The only risk factor was stabling all season (odds ratio 4.79; 95% CI 1.46-15.73). Tendon injuries were perceived as the major risk and hard ground the most important risk factor. Risk mitigation practices were bandaging before exercise (45.7%; 95% CI 34.8-56.5), checking tendons (84.0%; 95% CI 76.0-91.9), cold hosing (40.7%; 95% CI 30.0-51.4), bandaging (38.3%; 95% CI 27.7-48.9) and using clays and coolants after exercise (24.7%; 15.3-34.1). Cuts and wounds were considered most frequent by only 2.5% (95% CI 0.0-3.6) of players but were the second most common injury, accounting for 21.6% of veterinary treatments. Splints accounted for 12.5% of injuries.

CONCLUSIONS

The risk of injury to polo ponies is similar to that in the general horse population; musculoskeletal injuries, particularly tendon injuries, are most common, followed by wounds and splints. The association between stabling and injury, risk factors for wounds and splints and efficacy of cooling tendons post exercise warrant further study.

Epidemiology of musculoskeletal injuries in a population of harness Standardbred racehorses in training

Background

There is a substantial paucity of studies concerning musculoskeletal injuries in harness Standardbred racehorses. Specifically, little is known about the epidemiology of exercise-related musculoskeletal injuries. Most studies on this subject involve Thoroughbred racehorses, whose biomechanics and racing speed differ from Standardbred, making comparisons difficult. Here, a population of Standardbred racehorses trained at the same racecourse was studied over four years and a classification system for exercise-related musculoskeletal injuries was designed. The incidence rates of musculoskeletal injuries causing horses’ withdrawal from training for 15 days or longer were investigated. A mixed-effects Poisson regression model was used to estimate musculoskeletal injury rates and to describe significance of selected risk factors for exercise-related injuries in this population.

Results

A total of 356 trotter racehorses from 10 different stables contributed 8961 months at risk of musculoskeletal injuries. Four-hundred-and-twenty-nine injuries were reported and classified into 16 categories, based on their aetiology and anatomical localisation. The overall exercise-related injury rate was 4.79 per 100 horse months. When considering risk factors one by one in separate univariable analyses, we obtained the following results: rates did not differ significantly between genders and classes of age, whereas one driver seemed to cause fewer injuries than the others. Racing speed and racing intensity, as well as recent medical history, seemed to be significant risk factors (p < 0.001), while being shod or unshod during racing was not. On the other hand, when pooling several risk factors in a multivariable approach, only racing intensity turned out to be significant (p < 0.001), since racing speed and the racing intensity were partially confounded, being strongly correlated to one another.

Conclusion

Characterizing epidemiology of exercise-related musculoskeletal injuries in trotter racehorses provides baseline incidence rate values. Incidence rates of stress fracture are lower in Standardbreds compared to Thoroughbreds, whereas the opposite is true for tendon and suspensory ligament injuries. In addition to identification of risk factors for musculoskeletal injuries among Standardbred racehorses, results suggest that racing intensity seems to be a protective predictor of risk and recent medical history could be used to identify horses at risk of injury.

Deep digital flexor tendon injury within the hoof capsule; does lesion type or location predict prognosis?

The type and location of deep digital flexor tendon (DDFT) lesions may be important in predicting outcome. The objectives of this study were to determine the frequency of different types of DDFT lesions within the hoof capsule and to determine whether lesion type predicts return to athletic activity. Lesions of the DDFT were divided into: core lesions, dorsal border lesions and parasagittal splits. Lesion location was documented, and follow-up information was obtained by telephone survey at least 18 months after diagnosis. Of 168 horses with primary DDFT injury, 54 horses had dorsal border lesions, 59 had parasagittal splits and 55 had core lesions. Twenty-five per cent of all horses returned to previous levels of athletic activity within 18 months of MRI evaluation. Horses with complete splits or core lesions of the DDFT were significantly less likely to return to some level of athletic activity than horses with dorsal border lesions P<0.001. Dorsal border lesions of the DDFT appear to have a better prognosis than core lesions or parasagittal splits. This study provides additional information that may help clinicians predict the prognosis for different types of DDFT injury.

Investigating the efficacy of amnion-derived compared with bone marrow-derived mesenchymal stromal cells in equine tendon and ligament injuries

BACKGROUND AIMS

This is the first study to compare the treatment of horse tendon and ligament injuries with the use of mesenchymal stromal cells (MSCs) obtained from two different sources: amniotic membrane (AMSCs) and bone marrow (BM-MSCs). The objective was to prove the ability of AMSCs to exert beneficial effects in vivo.

METHODS

Five million allogeneic frozen-thawed AMSCs or autologous fresh BM-MSCs were injected intralesionally in horses belonging to group A (51 horses) and group B (44 horses). The interval lesion/implantation was of 6-15 days for the AMSCs and 16-35 days for the BM-MSCs. Healing was assessed clinically and ultrasonographically. Follow-up was monitored for 2 further years from return to full work.

RESULTS

No significant adverse effects after MSCs treatment were seen in any of the horses studied, independent of the type of stromal cell implanted. All animals belonging to group A resumed their activities between 4-5 months after treatment, whereas animals of group B resumed their activities after 4-12 months. The rate of re-injury in horses treated with AMSCs is lower (4.00%) compared with the average observed when horses were treated with BM-MSCs (23.08%).

CONCLUSIONS

The possibility to inject allogeneic AMSCs in real time, before any ultrasonographic change occurs within the injured tendon and ligament, together with the higher plasticity and proliferative capacity of these cells compared with BM-MSCs, represents the main features of interest for this novel approach for the treatment of equine tendon diseases. An obvious active proliferative healing in the area injected with AMSCs makes these cells more effective than BM-MSCs.

A case control study to investigate risk factors associated with horse falls in steeplechase races at Cheltenham racetrack

To date epidemiological reviews of fall risk in horse racing have applied a general approach to analysis integrating different grades, type of race and various racetracks. This study aimed to investigate if increasing specificity in analysis (one course and type of race) would expose the same risk factors for horse falls. The purpose of the study was to apply the principles of epidemiology to predict factors that increase the risk of a horse falling in steeplechase races at Cheltenham racecourse. Relevant factors related to horse falls were identified and collated from the Racing Post website for all steeplechase races run at Cheltenham between 1990 and 2010. Subsequent uni- and multivariable single-level and mixed effects logistic regression models were developed using ‘fall’ or ‘no fall’ as the dependent variables. The chance of a steeplechase race containing a minimum of one horse fall at Cheltenham racecourse is increased by 22% for each additional runner in the field and reduced by 86% for every horse that is pulled up during the race. Going and speed were not significantly associated with horse falls. Retrospective analysis of fall risk for a specific race type and course has exposed different risk factors than those previously found in generalised studies. Analysing specific racetracks has the potential to more effectively underpin the development and assessment of racecourse strategies to reduce fall risk to promote equine welfare.

The Grand National: a review of factors associated with non-completion and horse-falls, 1990 to 2012

The Grand National (GN) attracts high profile press and subsequent public attention. This study aimed to establish if factors influential to non-completion, horse-falls and specific fence risk in the GN supported the measures implemented by the British Horseracing Authority (BHA) to improve equine welfare in the GN. Horse, jockey, trainer and race related factors associated with non-completion, horse-falls and horse-falls at specific fences of the GN were collated over a 22 year period from 1990 to 2012. Descriptive analysis calculated non-completion rates per year, according to age and reason for non-completion. The distribution of fallers during the race in relation to fence number, design and key feature fences were also determined. Univariable analysis informed multivariable model building to identify factors associated with non-completion (n=840) and horse-falls (n=514) in the GN. Two final logistic regression models were refined through a backward stepwise process with variables retained if likelihood ratio test P-values were <0.05. Chi-square goodness of fit analyses evaluated fall risk at fence level. During the period investigated 347 horses completed the GN; the probability of a horse falling in the race was 0.24. The first fence, Becher's brook and drop fences increased the risk of falling compared to plain fences. Good-soft going increased the number of horses that completed the race and reduced the number of fallers suggesting this is the optimal ground condition for the race. GNs run at a faster than average speed increased the risk of horses not completing and falling. Inexperienced horses and jockeys show a greater risk of not completing and falling. Our work supports BHA measures implemented to improve safety in the GN; controlling speed, modifying fence design, promoting race experience and ground maintenance to produce good-soft going can increase completions and reduce falls, therefore enhancing equine welfare.

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in steeplechase starts in the United Kingdom (2001-2009)

The objective of this study was to identify risk factors for superficial digital flexor (SDF) tendinopathy in Thoroughbred horses in steeplechase races in the United Kingdom. Potential risk factors for SDF tendinopathy were studied between 1st January 2001 and 31st December 2009 using a cohort study design with 648 injuries sustained in 102,894 starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. In the final multivariable model, 12 statistically significant risk factors were identified. Variables that increased the odds of SDF tendinopathy included firmer going, increased horse age, and racing in the summer compared to other seasons. Variables that decreased the odds included having a higher official rating and the number of starts in the preceding days. Fewer and different risk factors were identified than in an equivalent model of SDF tendinopathy in hurdle racing, highlighting potential differences between these disciplines. Further collection of training and racecourse information would be beneficial and may help to explain further some of the associations identified in this study. The results will facilitate the development of strategies to improve overall safety of horses in UK steeplechase racing.