Risk factors for equine fractures in Thoroughbred flat racing in North America

The aim of this paper is to identify risk factors associated with equine fractures in flat horse racing of Thoroughbreds in North America. Equine fractures were defined as any fracture sustained by a horse during a race. This was a cohort study that made use of all starts from the racecourses reporting injuries. The analysis was based on 2,201,152 racing starts that represent 91% of all official racing starts in the USA and Canada from 1 st January 2009–31 st December 2014. Approximately 3,990,000 workout starts made by the 171,523 Thoroughbreds that raced during that period were also included in the analysis. During this period the incidence of equine fractures was 2 per 1000 starts. The final multivariable logistic regression models identified risk factors significantly associated (p < 0.05) with equine fracture. For example, horses were found to have a 32% higher chance of sustaining a fracture when racing on a dirt surface compared to a synthetic surface; a 35% higher chance if they had sustained a previous injury during racing and a 47% higher chance was also found for stallions compared to mares and geldings. Furthermore, logistic regression models based on data available only from the period 2009–2013 were used to predict the probability of a Thoroughbred sustaining a fracture for 2014. The 5% of starts that had the highest score in our predictive models for 2014 were found to have 2.4 times (95% CI: 1.9–2.9) higher fracture prevalence than the mean fracture prevalence of 2014. The results of this study can be used to identify horses at higher risk on entering a race and could help inform the design and implementation of preventive measures aimed at minimising the number of Thoroughbreds sustaining fractures during racing in North America

Laminitis: risk factors and outcome in a group of Danish horses

Reasons for performing study: Recent systematic reviews have highlighted the lack of quality information with respect to the epidemiology of equine laminitis. Objectives: To identify in Denmark the risk factors for new (i.e. not believed to have suffered from laminitis previously) cases of laminitis (NL) and to look at the outcome and incidence of repeated episodes of laminitis in these animals as well as those which had previously suffered an episode of laminitis (i.e. chronic cases) over the following 12 months. Methods: Information was obtained from 110 veterinary diagnosed cases of laminitis (69 new and 41 chronic) and 80 control animals (the next non-laminitic horse/pony seen by that participating practice). All animals were followed for up to one year. Univariable and multivariable conditional logistic regression was conducted for the NL case control pairs. Variables were retained within the final multivariable models if the likelihood ratio p-value was < 0.05. Results: There was no association between sex or gender and laminitis. A recent change of grass, being on what was considered high quality grass and being a cold-blooded type, <149cm ( i.e. Shetland, Fell, Welsh, or Dartmoor pony, Icelandic horse, Norwegian fjords, or a mix of these breeds) were all significant risk factors for laminitis. Although cresty neck score (CNS), and body condition Score (BCS), were significantly associated with NL at the univariable screening stage, they were found to be confounders of breed and each other during the multivariable model building process. Other factors such as weight, and estimated starch intake were not found to be significant .Thirty three percent of all the laminitis cases had been humanely destroyed within 12 months of diagnosis, mainly for laminitis associated reasons, compared with only 7.5% of the controls (none for laminitis associated reasons). Conclusions: and potential Relevance: This study confirms the importance of grass turn out and breed on laminitis risk. Horses in work at the time of diagnosis as well as those diagnosed in the winter and spring were more likely to be humanely destroyed within the next 12 months than those not in work or diagnosed in the autumn and summer

The impact of the mandatory rest period in Fédération Equestre Internationale endurance events

Background: Endurance riding competitions are increasingly popular, with a corresponding awareness of the frequency of Failure to Qualify (FTQ) due to lameness or metabolic problems. Fédération Equestre Internationale (FEI) rules require a minimum number of days between competitions, known as a mandatory rest period (MRP). Objectives: To analyse the impact on FTQ outcomes of MRPs which applied between January 2014 and December 2016, and model potential changes to MRPs to establish which rule change could lead to the largest further reduction in the number of FTQ outcomes. Study design: Retrospective cohort study and predictive model using a subset of data collected by the FEI of every horse start worldwide in Concours de Raid d’Endurance Internationale (CEI) competitions between 2010 and 2017. Methods: Descriptive statistics followed by predictive/retrospective modelling of potential scenarios. Scenarios involved extended MRP for all horses and/or for only the fastest ridden horses. Results: There were clear direct benefits demonstrated from the introduction of MRPs. Among directly affected horses, current MRPs could have prevented 2.3% of FTQ outcomes. Further benefits could be gained by extending MRPs. The ‘best‐value’ impact could be found in a 1‐week extension for all horses plus a 1‐week extension for the fastest ridden horses – which could result in a reduction of up to 11.5% of FTQ outcomes among directly affected horses. Main limitations: The data set covers all FEI competitions but no National Federation events. The data set is geographically comprehensive but it does not include every competition started by every individual horse. Training data for each horse were not available. Conclusions: Mandatory rest periods for horses between endurance competitions have had the intended impact of reducing numbers of FTQ outcomes in CEI events. Further benefits could be gained by extending rest periods for all horses and/or for horses ridden at the highest average speeds

A comparison between omeprazole and a dietary supplement for the management of squamous gastric ulceration in horses

Although several studies have assessed the short-term effect of dietary supplements on the treatment and prevention of gastric ulceration in horses, few have assessed the response over a duration of more than 30 days. A blinded randomized noninferiority clinical trial was conducted using 42 Thoroughbred horses in race training with squamous ulceration of ≥ grade 2/4, randomly assigned to one of two treatment groups for a period of 90 days: omeprazole at the full label dose of 4 mg/kg or the Succeed digestive conditioning supplement. Noninferiority analyses and Wilcoxon sign rank tests were used to analyze the data. At day 90, Succeed was noninferior to 4 mg/kg omeprazole administered daily in terms of the proportion of horses with complete resolution of squamous ulceration. At day 30, Succeed was found to be inferior to omeprazole in terms of the proportion of horses with grade ≤1/4 squamous ulceration. The proportion of horses with reducing squamous ulcer score (compared with day 0) was statistically significant for both treatments at days 30 and 60. At day 90 of the 17 horses on Succeed, nine had a reducing squamous ulcer score (P value = .049), and of the 19 horses on omeprazole, 10 had a reducing squamous ulcer score at day 90 (P value = .091). The noninferiority of Succeed compared to omeprazole at 90 days for the complete resolution of squamous ulceration and the reduced efficacy of omeprazole following 90 days of treatment are likely to be of interest to practitioners managing gastric ulceration in performance horses

Fédération Equestre Internationale (FEI) eventing: risk factors for horse falls and unseated riders during the cross‐country phase (2008‐2018)

Background: Eventing is an equestrian sport that tests athletes’ and horses’ skill over three phases: dressage, jumping, and cross-country. Falls during the cross-country phase can have very serious outcomes up to and including death for both horse and athlete. Therefore, understanding risk factors associated with falls is essential for improving equine and human welfare. Objectives: To provide descriptive statistics and identify risk factors at the horse-, athlete-, and course-level affecting horses competing in Fédération Equestre Internationale (FEI) events worldwide. Study design: Retrospective cohort study. Methods: Data collected by the FEI of every horse start worldwide in all international (CI), championship (CH), Olympics (OG), and World Equestrian Games (WEG) competitions between January 2008 and December 2018 were analysed. Descriptive statistics followed by univariable logistic regression to identify risk factor candidates for inclusion in the final multivariable logistic regression model. Models were constructed stepwise using a bi-directional process and assessed using the Akaike information criterion. Results: Factors associated with increased risk of falls and or unseated rider included: higher event levels, longer course distances, more starters at cross-country phase, and less experienced horses and athletes. Main limitations The data set is geographically comprehensive but covers only FEI competitions, not National Federation events i.e. not every competition started by every individual horse. Nor does the data set include any prior veterinary information or data on training or schooling. Conclusions: This is the first large-scale epidemiological study of cross-country falls in FEI eventing. Results suggest that a potential risk profile can be constructed for each horse-athlete combination prior to entering a given competition, based on individual histories and course-level factors. This could lead to interventions that can reduce the number of falls, thus protecting equine and human welfare

A genome-wide association study demonstrates significant genetic variation for fracture risk in Thoroughbred racehorses

Background: Thoroughbred racehorses are subject to non-traumatic distal limb bone fractures that occur during racing and exercise. Susceptibility to fracture may be due to underlying disturbances in bone metabolism which have a genetic cause. Fracture risk has been shown to be heritable in several species but this study is the first genetic analysis of fracture risk in the horse. Results: Fracture cases (n = 269) were horses that sustained catastrophic distal limb fractures while racing on UK racecourses, necessitating euthanasia. Control horses (n = 253) were over 4 years of age, were racing during the same time period as the cases, and had no history of fracture at the time the study was carried out. The horses sampled were bred for both flat and National Hunt (NH) jump racing. 43,417 SNPs were employed to perform a genome-wide association analysis and to estimate the proportion of genetic variance attributable to the SNPs on each chromosome using restricted maximum likelihood (REML). Significant genetic variation associated with fracture risk was found on chromosomes 9, 18, 22 and 31. Three SNPs on chromosome 18 (62.05 Mb – 62.15 Mb) and one SNP on chromosome 1 (14.17 Mb) reached genome-wide significance (p <0.05) in a genome-wide association study (GWAS). Two of the SNPs on ECA 18 were located in a haplotype block containing the gene zinc finger protein 804A (ZNF804A). One haplotype within this block has a protective effect (controls at 1.95 times less risk of fracture than cases, p = 1 × 10-4), while a second haplotype increases fracture risk (cases at 3.39 times higher risk of fracture than controls, p = 0.042). Conclusions: Fracture risk in the Thoroughbred horse is a complex condition with an underlying genetic basis. Multiple genomic regions contribute to susceptibility to fracture risk. This suggests there is the potential to develop SNP-based estimators for genetic risk of fracture in the Thoroughbred racehorse, using methods pioneered in livestock genetics such as genomic selection. This information would be useful to racehorse breeders and owners, enabling them to reduce the risk of injury in their horses

The association between clinical parameters recorded at vet gates during Fédération Equestre International endurance rides and the imminent risk of elimination

Background: Endurance competitions over distances of 80 to 160 km are required by Fédération Equestre Internationale (FEI) rules to be divided into between three and six stages, known as “loops”. Veterinary inspections, designed to ensure horse welfare, are conducted at the end of each loop, with details recorded on a separate “vet card” for each horse. Objectives: To identify risk factors recorded on vet cards that were associated with elimination at subsequent loops. Study design: Retrospective cohort study. Methods: Data relating to 3,213 horse starts worldwide in international (CEI) events during 2014 were analysed. Descriptive statistics and univariable logistic regression to identify risk factors for potential inclusion in the final multivariable logistic regression models. Models were constructed stepwise using backwards‐removal and assessed using the Bayesian information criterion. Results: Risk factors were identified, which would allow an “in‐ride” risk profile to be constructed for each horse which evolves as the horse progresses through the ride. Some risk factors such as abnormal gait and high heart rate were found to be repeatedly associated with imminent failure to qualify. Main limitations: This is a relatively small study in terms of cohort size, based on the data that were available at the time of the study. Although comprehensive ride history data were also available for each horse via the main FEI database, training data was not. Conclusions: By identifying risk factors observed during the veterinary inspections at the end of a loop that are strongly associated with elimination at the end of the next or subsequent loops, these results provide an evidence‐base for educational initiatives and regulatory changes that will inform the way veterinary delegates use veterinary inspections to help identify horses at risk of imminent FTQ

Effect of osteoarthritis on the repeatability of patella tendon angle measurement in dogs

Objective: To evaluate the influence of osteoarthritis on the measurement of patella tendon angle (PTA) and determine intraobserver and interobserver variability. Study design: Retrospective clinical study. Sample population: Eighty‐seven mediolateral radiographs that were obtained prior to tibial tuberosity advancement. Methods: Radiographic osteoarthritis was scored by 2 observers using guidelines derived from the International Elbow Working Group Protocol. Patella tendon angle was measured by 3 observers on 3 occasions, with at least 7 days between measurements. The data were statistically analyzed via weighted κ and Kruskal‐Wallis testing. Results: A fair strength of agreement was found among observers scoring osteoarthritis, with the same grades in 48% of radiographs. The intraobserver average bias between PTA measurements 1 and 3 ranged from −0.38° to −0.94°. Interobserver bias in angle measurement ranged from −0.92° to −2.00°. Observer 1 had the narrowest range of PTA differences (12.1°), and observer 3 had the highest range of PTA differences (23.5°). Observer 2 had the lowest mean bias (−0.38°). The mean bias was lowest between observers 1 and 2 (−0.92°) and highest between observers 1 and 3 (−2.0°). The mean intraobserver standard deviation of the PTA measurement differences was 2.90°, and interobserver standard deviation of the PTA measurement differences was 2.26°. The degree of osteoarthritis did not influence PTA measurements or their variability. Conclusion: The current study did not find evidence of an influence of osteoarthritis on PTA or on the repeatability of measurements. Clinical significance: Our findings suggest that osteoarthritis should not affect the radiographic planning for tibial tuberosity advancement surgery. The high variances in PTA measurement in less experienced observers may influence the clinical outcome of surgery

Risk factors associated with fatal injuries in Thoroughbred racehorses competing in flat racing in the United States and Canada

Objective: To identify risk factors associated with fatal injuries in Thoroughbred racehorses in the United States and Canada. Design: Retrospective study. Animals: 1,891,483 race starts by 154,527 Thoroughbred racehorses at 89 racetracks in the United States and Canada from 2009 to 2013. Procedures: Data were extracted from the Equine Injury Database, which contained information for 93.9% of all official flat racing events in the United States and Canada during the 5-year observation period. Forty-four possible risk factors were evaluated by univariate then multivariable logistic regression to identify those that were significantly associated with fatal injury (death or euthanasia of a horse within 3 days after sustaining an injury during a race). Results: 3,572 race starts ended with a fatal injury, resulting in a period incidence rate of 1.9 fatal injuries/1,000 race starts. Twenty-two risk factors were significantly associated with fatal injury. Risk of fatal injury was greater for stallions than for mares and geldings and increased as the number of previous nonfatal injuries and race withdrawals and level of competitiveness (eg, horse's winning percentage and race purse) of the horse or race increased. Conclusions and clinical relevance: Results identified several risk factors associated with fatal injuries in Thoroughbred racehorses. This information can be used as a guideline for the identification of racehorses at high risk of sustaining a fatal injury and in the design and implementation of preventative measures to minimize the number of fatal injuries sustained by horses competing in flat racing in the United States and Canada