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The aim of the research was to monitor current trends in international show jumping and assess how the proportion of Thoroughbred blood in the pedigree of horses, age, breed, sex and sport season influenced the competition results of show-jumping horses at the world level. The research was based on the databases of jumping rankings for the years 2010, 2014 and 2018 published by the International Federation for Equestrian Sports (FEI). All horses from the FEI rankings were included in the database with the exception of ponies and also horses lacking basic data. This yielded a total of 14,980 horses. The rankings of horses were calculated according to FEI methodology on the basis of the best 30 results every year in international show-jumping competitions with a minimum fence height of 1.45 m. The most represented breed was the Dutch Warmblood (19.26%) and the most common sex was gelding (43.98%). Since 2010 the standard proportion of Thoroughbred blood in the pedigrees of show-jumping horses has decreased and in 2018 the average proportion of Thoroughbred in the pedigree was 41.61%. The analysis of the statistics in the whole database established a significant (P ˂ 0.01) influence of all observed factors. The horses achieved a statistically higher ranking in 2018 (117.57) than in 2010 (98.33) and 2014 (105.93). The groups with a proportion of Thoroughbred between 30.10 and 70.00% achieved a significantly higher ranking than horses with a zero proportion of Thoroughbred in the pedigree. Stallions achieved a significantly higher ranking (117.84 points) compared to geldings (105.76 points) and mares (104.66 points). The horses aged 10–13 years old achieved better results (124.71 points) than the younger group of horses (76.66 points) and older group of horses (109.29 points, P = 0.0033). Statistically conclusive differences were found between AES horses (162.81 points) and the group of non-sport horse breeds (68.26 points) and also between AES horses and horses of unknown pedigree (38.61 points). There were no significant differences between the principal warmblood sport breeds produced in Europe. [ABSTRACT FROM AUTHOR]

Objectives: To determine the incidence of, and risk factors for, race-day jockey falls occurring in Thoroughbred flat and jumps (hurdle and steeplechase) racing.Design: Retrospective cohort study.Methods: Incidence rates for race-day jockey falls over 14 racing seasons in New Zealand (n=421,596 race-day starts) were calculated per 1000 rides. Univariable and multivariable analyses of jockey, horse and race level risk factors were conducted with Poisson regression in a generalized linear mixed model.Results: Most races (97%, n=407,948 race starts) were flat racing with 10 races/race-day, whilst most jumps races were longer and had 2 races/race-day. The rate of jockey falls was higher in steeplechase racing (99.9/1000, 95% CI 92.2-108.4) than hurdle (53.2/1000, 95% CI 48.7-58.3) and flat racing (1.2/1000, 95% CI 1.1-1.3, p<0.001). Experienced athletes (both horse and jockey) had lower IRR. In flat racing, IRR increased linearly with the number of race-day rides by the jockey. In jumps races, IRR increased with a fall in a previous race (IRR 1.5/1000, 95% CI 1.3-1.7, p<0.001). A shorter jumps race distance reduced the IRR of a jockey fall.Conclusions: Athlete experience was associated with risk of jockey falls. The linearity of race ride number with IRR and longer distance in jumps racing, indicated that cognitive or physiological fatigue may play a role in the risk of a race-day fall. This data highlights the role sport-specific conditioning programmes may have on reducing risk. [ABSTRACT FROM AUTHOR]

• Risk factors for limb deformities (LD)were evaluated in a Thoroughbred birth cohort. • Twenty-one percent of foals required veterinary intervention for LD in the first 6 months of life. • Early-life LD were not observed in foals with gestation lengths >360 days. • Risk of early-life LD reduced by 4% per day increase in gestation length (GL). • At GL of 320 to 360 days the final model predicted a LD prevalence of 40% to 10%. Flexural and angular limb deformities (LD) are an important cause of early-life morbidity and mortality/euthanasia in Thoroughbred foals. The majority are congenital in origin but, to date, their precise aetiology is poorly understood. We hypothesized that maternal- and pregnancy-level factors, particularly those with potential to influence in-utero growth and development, could play an important role. The aim of this study was therefore to investigate associations between such factors and early-life LD in Thoroughbred foals. A birth cohort was established on seven farms across the United Kingdom and Ireland and details of veterinary interventions for LD in foals in the first six months of life prospectively recorded. Details of dams' signalment, breeding history and reproductive and veterinary history in the breeding season(s) of interest were retrieved retrospectively from stud farm and veterinary records. Associations between mare- and pregnancy-level factors and LD in offspring were assessed using multivariable logistic regression. Records were available for 275 pregnancies in 235 mares, over two breeding seasons. Pregnancies resulted in the birth of 272 live foals, 21% of which (n = 57/272, 95% CI, 16–26) required veterinary intervention for LD in the first six months of life. Odds of LD decreased by 4% per day increase in gestation length between 314 and 381 days (OR 0.96, 95% CI, 0.93–0.99, P =.01). Longer gestation length appears to reduce the odds of early-life LD, including within the normal range of gestation length for Thoroughbred foals. Further work is required to elucidate biological mechanisms behind this association. [ABSTRACT FROM AUTHOR]

Highlights • First detection of Equine Hepacivirus (EqHV) in horses on the African continent. • Anti-EqHV antibodies are frequently detected in South African Thoroughbred foals. • EqHV seroprevalence in the study population is the highest reported to date. • EqHV strains circulating worldwide are closely related. Abstract Since the discovery of equine hepacivirus (EqHV) in 2011, the virus has been detected in horse populations from more than twelve countries across five continents. EqHV seroprevalence has been reported to be as high as 61.8% and EqHV ribonucleic acid (RNA) prevalence to range between 0.9% and 34.1%. Molecular and serological indications of EqHV infection have never been reported in equids on the African continent. Therefore, investigation of EqHV prevalence in South African horses and subsequent viral genetic characterization contribute to a better understanding of the global epidemiology of this virus. In a cross-sectional study, serum samples from 454 Thoroughbred foals (aged 58–183 days) were analysed for anti-EqHV non-structural protein 3 (NS3)-specific antibodies (abs) with a luciferase immunoprecipitation system (LIPS) and for EqHV RNA by quantitative real-time polymerase chain reaction (qRT-PCR). Farms of origin (n = 26) were situated in South Africa’s Western Cape Province. The associations between EqHV infection state and farm of origin, foal gender and foal age were subsequently described. Furthermore, nested PCRs were performed on parts of the 5′UTR, NS3 and NS5B genes of 17 samples. Samples were sequenced and phylogenetic analyses were conducted. The population’s seroprevalence was 83.70% and RNA was detected in 7.93% of samples. Increasing foal age was associated with decreasing ab prevalence and increasing prevalence of EqHV RNA. Sequences from South African EqHV strains did not show in-depth clustering with published sequences of EqHV isolates from particular continents. In conclusion, EqHV is present in the South African Thoroughbred population and appears more prevalent than reported in other horse populations worldwide. [ABSTRACT FROM AUTHOR]

Among the consequences credited to locomotor stereotypies in horses is the reduction of sport performance; however, there is a lack of studies on this topic. The objective of this study was to determine if racing performance was negatively affected by weaving and stall walking in thoroughbred racehorses. Three hundred eighty-nine animals were randomly chosen from those residing at the Club Hípico de Santiago, all of which had a handicap and had run at least 5 races. The horses were divided into 2 groups according to their handicap criteria: the low performance group, with handicap from 1 to 29 (n = 333) and the high performance group, with handicap from 30 to 56 (n = 56). Handicap is an index that is assigned to all thoroughbreds that participate in turf events, according to their performance (1 = poor to 56 = excellent performance). The presence or absence of weaving and/or stall walking was observed by visual inspection of each horse. Results were expressed as percentages. Fisher's exact test was used to analyze the data, with a significance level of P < 0.05. The average prevalence of weaving was 0.77%. Weaving was 0.3% in the low-performance group and 3.57% in the high-performance group. The average prevalence of stall walking was 2.83%. Stall walking was 3.3% in the low-performance group, and there were no horses with stall walking in the high-performance group. No relationship was found between the presence of both of the locomotor stereotypies studied here and handicaps. As there is no prior scientific research on this topic, our results preliminarily suggest that weaving and/or stall walking may not have an effect on racing performance in thoroughbred racehorses and thus, no efforts should be made to avoid this display based on this reason. [ABSTRACT FROM AUTHOR]

The aim of the present study was to analyze the effects of stallion and mare, their ages, and maternal lineage on the gestation length (GL) in Thoroughbreds. In addition, additive genetic effects of the dam, stallion and fetus were analyzed. Data were taken from 1993 through 2009, and included 16,226 pregnancies from 5959 Th oroughbred mares mated with 290 different stallions. All analyses were performed using linear mixed models. The GL ranged from 306 to 390 days, with a mean length of 347.0 ± 14.4 days. Mating of mares with stallions aged 17 years and older resulted in a significantly longer GL compared to younger stallions. Furthermore, the GL significantly increased with the increasing age of the mares, and the GL was longer with male foals. The month and year of breeding, as well as the mare´s breeding history (parity and reproductive status) also affected GL. The mare and stallion themselves explained 18% and 4% of the variance in GL. Coefficients of inbreeding of mares and foals had no significant effect on GL. The heritability for the GL was 0.17 for the dam and 0.006 for the fetus, whereas an additive genetic paternal effect was not estimable. The relative proportions among the additive genetic and permanent environmental contributions of the dam were 76.5% and 23.5%. A maternal lineage effect was not obvious. [ABSTRACT FROM AUTHOR]

Previous work has demonstrated that 2-year-old horses in race training experience a decrease in inflammatory cytokine production as work at higher speeds progresses. The goal of this study was to determine whether training methods influence inflammatory gene production in 2-year-old horses; as such, two groups of horses trained using different high-speed training regimens (traditional, twice weekly, flat-track training on an all-weather surface vs. once weekly training on a grass track and regular work over undulating hills) were enrolled in this study. Peripheral blood samples were obtained on a weekly basis to measure the in vivo inflammatory mRNA expression of 10 different markers. Relationships between the markers were analyzed, and an Inflammation Score (IS) created from the average of all 10 markers for comparison between the two different training groups. Overall, while there were multiple marker relationships between the groups that were expected based on established inflammatory pathways, there were also relationships seen only in one group instead of the other, including a novel, positively correlated relationship between IL-17 and VEGFA in the traditional training group. Additionally, over time, the traditionally-trained group experienced a significantly increased IS compared with the grass-trained group, demonstrating that some training regimens may induce more inflammation in horses than others. [ABSTRACT FROM AUTHOR]

Monitoring racehorse fatality and associated jockey falls provides benchmarks for intervention strategies. The aims of this study were to describe the incidence of and reasons for fatalities in Thoroughbred horses during flat races in the Australian Capital Territory and New South Wales (NSW), Australia, and to describe reported jockey falls and injuries associated with racehorse fatalities. A cohort study identified all racehorse fatalities reported through Racing NSW for the 2009–2010 to 2013–2014 racing seasons. Risks of racehorse fatality, fatal musculoskeletal injury, spontaneous death (as distinct from euthanasia) and racehorse fatality associated jockey falls and injuries were calculated using Poisson regression. A total of 167 horse fatalities were reported, with an overall incidence of 0.59 deaths/1000 starts. Forty-nine reasons for horse fatality were reported, although post-mortem examinations were conducted on only 52/165 (31.5%) horses. Musculoskeletal injury accounted for 144/167 (86.2%) fatalities, with an incidence of 0.52/1000 starts. Fractures comprised 96/167 (57.5%) fatalities, with the fetlock or proximal sesamoid bones being the most common fracture location, comprising 36/96 (37.5%) fractures. Only 22/166 (13.3%) racehorse fatalities were due to spontaneous death, representing an incidence of 0.08/1000 starts. A total of 50 racehorse fatality associated jockey falls were reported (incidence of 0.18/1000 starts), with 32 reported jockey injuries (incidence of 0.12/1000 starts). Most racehorse fatality associated jockey injuries occurred to the limbs (17/32, 53.1%), particularly the upper limb. The estimates for both horse fatality and associated jockey injury were comparable with previous estimates from other jurisdictions internationally. [ABSTRACT FROM AUTHOR]

To determine associations between carpal and fetlock conformation and later performance, 292 two-year-old (2YO) Thoroughbred horses were examined at a public auction. Two observers graded carpal and fetlock conformation in the frontal view, and subject weights were estimated (weight tape), and height was measured. Subject age, gender, and workout distance and time were retrieved from sales data. Lifetime racing data was retrieved from the Jockey Club database. Mild to moderate deviations from straight forelimb conformation at the carpus or fetlock occurred in 85% of 2YO Thoroughbreds and had no substantive effect on lifetime racing performance. Carpal and fetlock conformation are associated. Greater age, female gender and faster workout were associated with better short and long-term racing outcomes. The ability to start a race at 2YO was associated with improvements in several measures of racing success. The lack of an association of forelimb conformation with most measures of racing performance will assist producers and consumers of young racing stock in the determination of the need for corrective procedures in young horses and the importance of deviations at purchase. Speed of workout and the ability to start at 2YO were associated with each other and with an improvement in several racing outcomes. [ABSTRACT FROM AUTHOR]

Racehorses in New Zealand predominantly train counter clockwise. This training pattern has been associated with between forelimb differences in bone mineral density profile and asymmetrical limb loading after training. At present, there is limited data on the hoof conformation of these racehorses. Distal forelimb and digital hoof conformation data were collected from 75 Thoroughbred racehorses (2–5 years old) from two training yards. Digital conformation was subjectively graded, and multiple hoof measurements were made with a modified tire gauge (sole and sulci depth) and from digital photographs. All the horses were shod by two registered master farriers within a median of 15 (interquartile range [IQR], 1–25) days before measurement. There were few distal limb conformation abnormalities scored. Most (62/75) horses presented with some deviation from normal hoof parameters, with 2 (IQR, 1–3) abnormalities reported per horse. The most common hoof abnormality was uneven sulci, which was identified in 43 horses and 59 affected hooves, followed by higher medial hoof wall height in 38 horses and 53 affected hooves. Many of the linear and hoof angle measurements and their ratios were within the bounds reported within the literature and indicative of a balanced foot. The length and width measurements increased with horse age. The dorsal hoof wall (DHW) length:heel length ratios were consistently less than 3:1, and the absolute difference between toe and heel angle was generally greater than 5°. Between limb hoof variation was identified for a number of the morphologic measurements including frog length and sole length and the ratio of sole width:sole length. Flat feet (lack of concave solar surface) were identified in 21/75 (28%) horses and in 28/150 (19%) forelimb hoofs. More horses had a flat left foot (10/75) than right foot (4/75), but seven horses had both feet classified as being flat. Flat feet had 2.4 (1.1–5.6, P = .036) greater odds of presenting with uneven sulci. These data indicate that uneven sulci depth and flatter hooves with may be a typical presentation of Thoroughbred feet. Asymmetry in measurements between limb may reflect the greater loading of the left forelimb when race training counter clockwise. [ABSTRACT FROM AUTHOR]

During the dissection and skeletal examination of 151 horses, a congenital malformation (CM) of the first sternal rib that influenced the aperture of the Thoracic inlet was noted in six horses. The presentation of this CM was variable between horses in gross anatomic appearance; notably, an absent first sternal rib, bifid tuberculum costae, bifid sternochondral articulation onto the sternum, flared shaft, normal first sternal rib inserting onto the cranial branch of a bifid sternochondral articulating second sternal rib, straight costal shaft, and an articulating rudimentary tuberculum costae with a ligamentous extension replacing the bony shaft and attaching to a rudimentary sternochondral articulation onto the sternum. Of the 151 horses examined, the CM of the first sternal rib was restricted to 6/60 Thoroughbred horses, and only in those that were affected by either the unilateral or bilateral transposition of the caudal ventral tubercle from C6 onto the ventral surface of C7. The normal anatomic presentation of the thoracic inlet was altered, along with associative musculature including neurological pathways. These CMs are likely to produce clinical and functional ramifications of the thoracic inlet, thoracic limb, and thoracic viscera, with the probability of altering postural and locomotive function as noted in four horses demonstrating the CM. [ABSTRACT FROM AUTHOR]

Thoroughbreds are best known for their careers as racehorses, a career that often concludes between the ages of 3 and 6. After racing, Thoroughbreds can perform successfully in other disciplines like eventing and dressage. However, the owner demand for off-the-track Thoroughbreds (OTTBs) as mounts for second careers is not well characterized. Therefore, the objective of this study is to quantify the buyer demand for OTTBs that have started second riding careers and are being marketed through a virtual auction. Horse and auction characteristics were collected on 170 Thoroughbred horses across 39 online sport horse auctions between 2012 and 2020. Data were analyzed using ANOVA (α = 0.05) and mean separations were assessed using Tukey's HSD when appropriate (STATA 16). Bids ranged from $100 to $20,000 and the average was $2,528.25 ± 3,011.37 (mean ± SD). Horse age impacted (P = 0.001) the bid price, where each additional year increased bid price by $430.50 ± 158.7. However, when the age was squared to model an aging horse, bid price decreased (P = 0.001) with age (-$22.91 ± 6.74). Additionally, geldings brought a premium of $924.08 ± 427.84 over mares, displaying buyer preference for geldings. Horse color, especially chestnuts ($1,071.07 ± 555.28; P = 0.05) and grays or roans ($1,054.05 ± 536.41; P = 0.05), brought premiums over bay or black horses. Horse height did not (P > 0.05) impact bid price, nor did Jockey Club registration (P > 0.05) or previous training in most English riding disciplines (P > 0.05). Horses listed as trail riding mounts, though, received discounts (-$1,599.46 ± 604.58; P = 0.001) compared with other disciplines. Of the auction logistics, only registration in USEF or USHJA or USEA affected (P = 0.01) bid price, where registration increased sale price by $1,967.33 ± 820.24. This interest shows that bidders value horse registration and could suggest a valuable tool for sellers to increase their horse's bid price. By characterizing the discounts and premiums for horse and auction characteristics, equine bidders can better expect what a horse may sell for, and which attributes could lend them more competition when actively bidding. Additionally, sellers can use this information to not only calculate what premiums or discounts their horse may sell with, but sellers can increase their horse's bid by enhancing their profile with registration. [ABSTRACT FROM AUTHOR]

• Speed, distance and time metrics tend to increase in accordance with level of play, also typically showing a concomitant reduction in variability • Women's Polo is comparable to 0– and 6–goal Polo, when comparing within-tournament measures and accompanying variability • Polo, irrespective of level, shows a high degree of between tournament variability. This is driven by within-subject variability which exceeded that of between-subject variability. • Z-scores are a convenient and useful method for capturing and displaying between tournament variability. This paper provides exemplar boundaries for practitioners considering this approach in Polo. The external work, as measured by global positioning systems, undertaken by Polo ponies during tournament play has been well-described across Polo of varying levels in both Open and Women's Polo. However, the variability within these data have not been thoroughly examined. Understanding the variability within these data between players (within-tournament variability) and between tournaments allows a deeper understanding of expected Polo performance and can inform coaching and tactical decisions, as well as aid in longitudinal horse development and comparison to other equestrian disciplines. The present paper captured data from 618 chukkas of Polo, in levels ranging from 0– to 16–goal and Women's Polo, across three New Zealand Polo seasons. Standard error and coefficient of variation were calculated to assess within-tournament variability; between-tournament variability was assessed via median percentage difference and Spearman's rho correlation coefficients. Playing duration, speeds (average and maximum) and distance metrics (total and standardized speed zones) typically increase with level of Polo play, with a concomitant reduction in within-tournament variability also seen. Nought (0–), 6–goal and Women's Polo show comparable within-tournament measures and associated variability. Polo, shows a high degree of between-tournament variability as within-player variability often exceeds that of between-player variability, affecting mathematical interpretations of reliability. Z-scores are a convenient alternative method for capturing and displaying between-tournament variability for the examined parameters, facilitating comparing across tournaments and seasons. Exemplar boundaries for this approach in Polo are provided. [ABSTRACT FROM AUTHOR]

The first aim of this study was to analyze the behavioral traits and heart rate (HR) parameters in Thoroughbreds soon after the horses had finished their racing careers. The second aim was to select those traits, from those previously analyzed, which that would indicate the horses' further suitability for equestrian sports. The study was performed on 25 two-year-old Thoroughbred mares and geldings that had finished their racing careers. An initial observation was made by a jockey on the racing track. The first test evaluation was carried out on the 10th day after their return from the track to their home studs and the next 2 evaluations took place 1 and 2 months after the first assessment. The last (verifying) evaluation was performed 12 months after the first test evaluation. Between the first and last assessments, the horses were systematically trained to prepare them for equestrian sports. The first 3 assessments were based on behavioral observations and HR parameters. The verifying examination of a horse's suitability for recreational purposes with regard to its behavior was performed by a test rider. The results showed that it was possible to initially assess the suitability of a Thoroughbred for recreational purposes according to 2 groups of attributes: behavioral and HR and heart rate variability parameters. The behavioral analysis focused on the behavior of a horse when a person enters the box and when a horse faces an unknown object. HR and heart rate variability parameters assessed included HR measurements when a person enters the box and during bridling and root mean square of successive differences measurements when a person enters the box and when a horse faces an unknown object. This second assessment occurred 1 month after a horse returned from the racing track to the mother stud. As indicated by the results, 1 month is the critical period needed to adjust to new circumstances after being on the racetrack. Earlier examination might not be accurate. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of aging on biochemical markers in serum obtained from Thoroughbred horses (n = 30) and ponies (n = 15). Aging was observed to have an effect on albumin, total bilirubin, thyroxine, and iron levels. The triglyceride concentration in ponies was found to be significantly higher than in Thoroughbreds. Furthermore, an age-related increase in triglycerides was only observed in ponies. There was no aging effect on diacron-reactive oxygen metabolites and biological antioxidant potential concentration. A significant negative correlation between age and bilirubin, known as a strong antioxidative substance, was obtained in both the Thoroughbred and pony groups. However, the distribution area of data was different due to higher bilirubin concentrations in Thoroughbreds. The serum iron levels were correlated with serum triglyceride levels in ponies. We propose that the metabolism of ponies differs from that of Thoroughbreds and that careful breeding and appropriate exercise are required for aging ponies. [ABSTRACT FROM AUTHOR]

Identification of risk factors which are associated with severe clinical signs can assist in the management of disease outbreaks and indicate future research areas. Pregnancy loss during late gestation in the mare compromises welfare, reduces fecundity and has financial implications for horse owners. This retrospective study focussed on the identification of risk factors associated with pregnancy loss among 46 Thoroughbred mares on a single British stud farm, with some but not all losses involving equid herpesvirus-1 (EHV-1) infection. In a sub-group of 30 mares, association between pregnancy loss and the presence of five common Thoroughbred horse haplotypes of the equine Major Histocompatibility Complex (MHC) was assessed. This involved development of sequence specific, reverse transcriptase polymerase chain reactions and in several mares, measurement of cytotoxic T lymphocyte activity. Of the 46 mares, 10 suffered late gestation pregnancy loss or neonatal foal death, five of which were EHV-1 positive. Maternal factors including age, parity, number of EHV-1 specific vaccinations and the number of days between final vaccination and foaling or abortion were not significantly associated with pregnancy loss. In contrast, a statistically significant association between the presence of the MHC class I B2 allele and pregnancy loss was identified, regardless of the fetus/foal’s EHV-1 status (p = 0.002). In conclusion, this study demonstrated a significantly positive association between pregnancy loss in Thoroughbred mares and a specific MHC class I allele in the mother. This association requires independent validation and further investigation of the mechanism by which the mare’s genetic background contributes to pregnancy outcome. [ABSTRACT FROM AUTHOR]

The observation of locomotor activity and resting behavior is used to determine time budgets, which may give some indication for the assessment of horses' welfare concerning management and housing. The aim of this study was to investigate total locomotor activity (TLA) daily rhythm in athletic horses (Thoroughbred, Standardbred, and Italian Saddle), with special attention to the intrasubject and intersubject variabilities. Ten subjects for each breed were divided into two subgroups, one housed in box and one housed in paddock. TLA was recorded for 10 consecutive days by mean of an activity data logger, Actiwatch Mini, applied at each horse by mean of a headstall. The obtained data were analyzed using the method of single cosinor. All horses, in all experimental conditions, showed a daily rhythm of TLA. On the obtained circadian parameters (mesor, amplitude, acrophase, and robustness), a multivariate analysis of variance was applied to investigate the effect of breed, housing conditions, and days of monitoring. It showed a statistically significant effect of breed on all circadian parameters; an effect of housing condition on mesor, amplitude, and robustness; and an effect of days of monitoring on acrophase and robustness. The analyses of intrasubject and intersubject variabilities indicate that organization of TLA daily rhythm in Standardbred and Jumper is characterized by greater accuracy of control within and between the individuals of a breed. In contrast, Thoroughbreds showed a high intrasubject and intersubject variability for all parameters studied, except for the intravariability of acrophase, denoting a different response to noxious stimuli that was observed not only among the subjects but also within the subject. [ABSTRACT FROM AUTHOR]

• Treatments were administered following three quarters of coverings • Two thirds of post-covering treatments included intrauterine antibiotics • Over a third of mares without visible intrauterine fluid still received post-covering treatment • A third of mares required veterinary care for disease or injury during gestation • Half of mares received at least one non-reproductive medication during gestation The study aimed to (1) describe the use of reproductive therapeutics; (2) estimate the incidence of disease and injury; and (3) describe non-reproductive medications administered during pregnancy in Thoroughbred broodmares. A prospective birth cohort was established on seven farms across the UK and Ireland. Details of dams' signalment, breeding history, reproductive management during the breeding season(s) and veterinary-attended episodes of illness or injury and medication usage during gestation were retrieved retrospectively for 275 pregnancies in 235 mares over two breeding seasons. Results are reported at pregnancy-level of mares with data available. Preoestrus medications, ovulatory agents and post-covering treatments were administered to 55% (n = 85/155, 95% Confidence interval (CI) 47–62), 64% (n = 101/157, 95% CI 57–71) and 73% (n = 109/150, 95% CI 65–79) of mares respectively. Antibiotics were utilized in 69% (n = 75/109, 95% CI 60–77) of post-covering treatments. Of mares with no visible fluid on post-covering ultrasound, 37% (n = 24/65, 95% CI 26–49) still received treatment. Thirty-four percent (n = 70/203, 95% CI 28–41) of mares suffered at least one veterinary-attended episode of disease or injury, with conditions affecting the musculoskeletal system (23%, n = 46/203, 95%CI 17–29) and placentitis (5%, n = 10/203, 95% CI 3–9) most prevalent. Forty-seven percent (n = 95/203, 95% CI 40–54) of mares received at least one non-reproductive medication during gestation, antibiotics (25%, n = 51/203, 95% CI 20–31) and non-steroidal anti-inflammatory drugs (23%, n = 47/203, 95% CI 18–29) being most frequently prescribed. Post-covering treatments often included antibiotics and were sometimes given in the absence of fluid, highlighting a need to further understand therapeutic rationale. Disease occurrence and medication usage during gestation were frequent and warrant additional investigation. [ABSTRACT FROM AUTHOR]

• Levels of phosphorylated neurofilament heavy chain in clinically healthy and injured Thoroughbred racing horses were compared in a case-control study. • There was no significant association between the levels of phosphorylated neurofilament and the risk of catastrophic injury. • Association between Phosphorylated neurofilament heavy subunit in serum and putative risk factors for catastrophic injuries in Thoroughbred racing horses Neurofilaments are structural proteins that are concentrated in the body and axons of neurons. Damage to the neurons or axons as a result of trauma or infectious diseases leads to the release of neurofilaments into blood and cerebrospinal fluid (CSF). This case-control study was carried out to compare serum levels of phosphorylated neurofilament heavy chain (pNF-H) between clinically healthy Thoroughbred (TB) horses and TB horses that suffered catastrophic musculoskeletal injuries (cMSI), and to investigate the correlation between putative risk factors and serum concentrations of pNF-H in injured horses. Blood samples were collected from clinically healthy horses and from horses that suffered cMSI. The concentration of pNF-H in serum samples was determined using the Phosphorylated Neurofilament H Sandwich enzyme-linked immunosorbent assay kit. A total of 343 horses were enrolled in the study (148 cases and 195 controls). The median serum concentration of pNF-H for controls was 0.0 ng/ml and for cases was 0.07 ng/ml. No significant difference was observed between the 2 groups in racing. The number of lifetime starts was correlated with serum pNF-H concentration in case horses. The serum concentration of pNF-H was higher in case horses that experienced cMSI while training than while racing. The number of lifetime starts is a proxy measure for several risk factors related to cumulative exercise load during the career of racehorses. Measurement of serum concentrations of pNF-H in TB racehorses does not support the hypothesis that subclinical neurologic injury or conditions are associated with catastrophic injury of TB racehorses. [ABSTRACT FROM AUTHOR]

During the dissection of seven Thoroughbred (Tb) and two Thoroughbred derivative (TbD) horses (9) displaying the congenital malformation of C6 and/or C6 and C7; variations in the gross morphology of the Longus colli muscle were noted. In the absence of the caudal ventral tubercle (CVT) on C6 only, the insertion of the medial and ventral layers and thoracic portion of the L. colli muscle attached to the cranial ventral tubercle (CrVT) on C6. However, on transposition of the CVT from C6 to the ventral surface of C7, the medial and ventral layers, a single deep bundle, and thoracic portion of the L. colli muscle attached to the CrVT on C6 and the transposed CVT on C7. In the unilateral malformation, this placed a distinct asymmetry in the paired left-to-right longitudinal presentation and cross-sectional samples of the L. colli muscle. In the bilateral malformation, the CrVTs were longitudinally malaligned and the L. colli replicated the unilateral presentation to a lesser extent. In this presentation, asymmetry was noted in entheses patterns and articular process joints, implying abnormal mechanical load, as was confirmed in the cross sections. As the L. colli muscle has specific cybernetic roles linked to posture and locomotion, these anatomic variations imply dysfunction. Premortem examinations confirmed eight of the nine horses exhibited proprioceptive and neurologic dysfunction (stillborn not included). This raises questions as to the equilibrium of affected horses and therefore the safety in handling and riding such horses, as was found in this study. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the correlation between front limb conformation and the development of superficial digital flexor tendon (SDFT) lesions in flat racing Thoroughbred horses. Ninety-three 4-year-old flat racing Thoroughbreds trained in the same training facility were included in the study; 66 horses were orthopedically sound, and 27 had a history of an SDFT injury. Four different radiographic images of the distal parts of both front limbs were taken from each horse. After testing the repeatability of 18 digitally measured parameters, these measurements were taken for all the animals. The possible effect of conformation on SDFT lesion development was assessed by analyzing the association between each measured variable and the sound and/or lesion status of the horses. Differences between the two groups for each parameter were analyzed using t statistics. Sound horses showed a greater proximal interphalangeal dorsal joint angle than horses with an SDFT lesion. A smaller distal width of the middle phalanx was also associated with fewer tendon lesions. However, none of the measured conformational parameters showed a strong association with the development of SDFT lesions. It appears that conformational traits of the distal parts of the forelimb of flat racing Thoroughbreds are not a major contributing factor to the development of SDFT injury if analyzed separately. [ABSTRACT FROM AUTHOR]

Radiographic abnormalities (RAs) in the proximal interphalangeal (pastern) joint have several manifestations and can cause concern in young horses intended for racing. Our objective in this retrospective study was to describe the appearance and prevalence of pastern RAs in young Thoroughbreds and compare the racing outcomes of cases with sibling controls. All radiographic reports of young Thoroughbred racehorses born in 2003–2007 read by veterinarians in one Lexington, Kentucky, practice were searched for pastern RAs. Pastern RAs are described, and the 2- and 3-year-old racing records of affected horses are compared with siblings. Pastern RAs were detected in 1.3% of weanling and yearling Thoroughbred horses examined. Radiographic abnormalities detected included shallow (≤3 mm) indentations in joint contour, dorsal osteophytes or axial palmar and/or plantar enthesophytes (≥3 mm), osseous fragments, and subchondral lucencies (≥4 mm). Horses with fragments in the pastern joint tended to be less likely to start a race at 2 years of age. Horses with fragments and subchondral bone cysts in the distal first phalanx tended to be less likely to start a race at 2 or 3 years of age than control siblings. The importance of some pastern joint RAs to performance can be overemphasized; however, some RAs have a tendency to be associated with poorer racing outcomes than sibling controls and may be considered when reviewing the radiographs of young Thoroughbred racehorses. [ABSTRACT FROM AUTHOR]

The purpose of this short report is to describe the influences on the pricing of Thoroughbred (TB) horses for the adult recreational riding market. Research into the association between horse breed and specific behaviors supports the view that some breeds are more reactive than others. There is anecdotal evidence that TBs may be more likely than other breeds to show traits that compromise rider safety. Having been bred for speed and reactivity, TBs may have reduced habituation tendencies. In addition, those that have raced may have had more training to accelerate than to decelerate and as such may be predisposed to uncontrollable flight responses. We examined data from advertisements to determine which descriptors influence the price of TBs (n = 220) entering the adult riding horse market. Linear regression analysis of log(price) revealed that variates such as a larger total sum of performance experience and bigger advertisements ( P < 0.001), all significantly increased the price set by vendors. The inclusion of trail riding in the advertisement had a detrimental influence on price ( P < 0.001). Dressage experience was associated with increased pricing ( P = 0.002). The inclusion of positive descriptive terms associated with safety had a rather smaller and less significant effect ( P = 0.012) on price. The average advertised price of $3,286 for a TB was significantly cheaper than the average advertised price of a non-TB horse ($7,384; P < 0.001). In contrast to the findings for the ponies and non-TBs previously reported using the same method, reassuring descriptors had a significant positive influence on price of TBs. These data confirm that TBs are valued differently to other breeds in the Australian adult riding horse market. [ABSTRACT FROM AUTHOR]

It is in the horse racing industry's interest to understand all factors that impact performance to maintain the integrity of the sport. There is some evidence that the start of flat races can affect racehorse performance. However, limited research exists on the explicit effect that waiting at the start and inside starting stalls (also known as starting gates or barriers) has on racehorse finishing position. This study investigated how temporal, behavior and loading related factors associated with the period before the start of the race influences racehorse performance. A cross-sectional design evaluated performance of 546 horses across eight flat race days at Chelmsford City Racecourse in November and December 2020, using televised racing coverage. Time horses spent inside starting stalls, the use of loading aids and jockey behaviors were recorded. Notational analysis was used to determine how much horses sweat and their behavior before, during and after loading. Behavior was categorized using an ethogram adapted from previous published research recording conflict behavior in horses. Horses that spent under 50 s inside starting stalls were more likely to win (p < 0.05) or finish in the top three (p < 0.01). Those showing moderate adverse behavior before loading (p < 0.01) and no adverse behavior inside stalls (p < 0.05) were more likely to win and place first to third, respectively, although behavior during loading had no significant effect. Horses sweating to the point of foaming (p < 0.01) and requiring specialist loaders (p < 0.05) were more likely to win, although the use of other loading aids did not significantly affect performance. Jockeys that pushed their bodyweight forwards in the saddle during loading were significantly more likely to place first to fourth (p < 0.05). A horse's chance of placing first to third was reduced by 15% for every increase in drawn order (p < 0.01; CI:0.77–0.96) and by 59% when the horse spent over 50 s inside stalls (p < 0.05; CI:0.19–0.92). A horse's likelihood of placing decreased by 13% for every year of age (p < 0.05; CI:0.78–0.97) and by a further 17% for each additional horse in the field (p < 0.001; CI:0.00–0.83). Racehorses showing adverse behavior inside stalls were 52% less likely to place (p < 0.05; CI:0.00–0.48). This research demonstrates that the start of flat races can influence performance, highlighting the importance of warm-up protocols and starting gate training to optimise performance. With further longitudinal research, these findings could support adjustments to the rules of racing regarding the start to improve and maintain the integrity of horseracing in the UK. • Racehorse behavior at the start and in starting stalls affects race performance. • Horses inside starting stalls for a shorter time are more likely to win and place. • Willingness to load and loading aids do not seem to affect racehorse performance. • The amount horses sweat prior to racing affects subsequent finishing position. [ABSTRACT FROM AUTHOR]

An 8-year-old Thoroughbred mare presented with acute bilateral epistaxis. The mare showed no clinical signs other than cough and profuse bilateral epistaxis. Antibiotic therapy was instituted and a transtracheal wash was collected. Large numbers of inflammatory neutrophils and gram-positive cocci were reported in the tracheal wash. The antibiotic therapy was continued for 7 days at which time the mare appeared clinically normal. The mare was successfully bred and was confirmed pregnant. She was referred to a hospital when the epistaxis recurred. She was treated with another antibiotic, and thoracic radiographs were also taken which revealed a space occupying lesion. The mare foaled a live foal. She developed bilateral thickening of her limbs. The swellings were of boney consistency and affected all four legs, particularly the forelimbs. A diagnosis of pulmonary hypertrophic osteopathy was made. The mare was again sent for further investigation. The thoracic mass had increased in size from the first examination. A biopsy was collected by endoscopy which confirmed a neoplastic process. After deterioration in her condition, the mare was euthanized on humane grounds. An autopsy report revealed that the mare had approximately 80% of the left lung replaced by neoplastic tissue. The right lung contained many small nodular masses. There was an associated cardiomegaly. In this case, the development of periosteal proliferation in multiple metaphyses was secondary to an intrathoracic neoplastic mass. [ABSTRACT FROM AUTHOR]

During the dissection and skeletal examination of 123 horses, it was observed that a significant number had a gross skeletal congenital malformation of the sixth and seventh cervical vertebrae. In the sixth cervical vertebra (C6), either a unilateral or bilateral absence of the caudal ventral tubercle (CVT) was noted. In the presence of the C6 malformation, the seventh cervical vertebra (C7) presented either as normal or with a unilateral or bilateral transposition of the CVT from C6 onto the ventral surface of C7 with an arterial foramen. This transposition onto C7 was noted to be present on the corresponding side as the absent CVT on C6. Of the 123 horses examined, the congenital malformation of C6 was noted in 19 of 50 Thoroughbred horses; three of three Thoroughbred derivative horses; one of 15 nondescript bred horses; and none of 55 purpose bred horses of mixed breeds. In total, 23 horses expressed a C6 congenital malformation of which 22 were Thoroughbreds or Thoroughbred derivatives. Of these 22 Thoroughbred and Thoroughbred derivative horses, 11 of 22 expressed either a unilateral or bilateral transposition of the CVT from C6 onto the ventral surface of C7 with an arterial foramen on the corresponding side. This malformation could have functional and clinical ramifications in the postural and locomotive properties of the equine neck and cervicothoracic junction as reported in other species. [ABSTRACT FROM AUTHOR]

A retrospective cohort study of distal limb fracture and superficial digital flexor tendon (SDFT) injury in Thoroughbred racehorses was conducted using health records generated by the British Horseracing Authority (BHA) between 2000 and 2010. After excluding records of horses that had both flat and jump racing starts, repeated records were reduced to a single binary record per horse (n = 66,507, 2982 sires), and the heritability of each condition was estimated using residual maximum likelihood (REML) with animal logistic regression models. Similarly, the heritability of each condition was estimated for the flat racing and jump racing populations separately. Bivariate mixed models were used to generate estimates of genetic correlations between SDFT injury and distal limb fracture. The heritability of distal limb fracture ranged from 0.21 to 0.37. The heritability of SDFT injury ranged from 0.31 to 0.34. SDFT injury and distal limb fracture were positively genetically correlated. These findings suggest that reductions in the risk of the conditions studied could be attempted using targeted breeding strategies. [ABSTRACT FROM AUTHOR]

A retrospective cohort study of important musculoskeletal conditions of Thoroughbred racehorses was conducted using health records generated over a 15 year period (n = 5062, 1296 sires). The prevalence of each condition in the study population was: fracture, 13%; osteoarthritis, 10%; suspensory ligament injury, 10%; and tendon injury, 19%. Linear and logistic sire and animal regression models were built to describe the binary occurrence of these musculoskeletal conditions, and to evaluate the significance of possible environmental risk factors. The heritability of each condition was estimated using residual maximum likelihood (REML). Bivariate mixed models were used to generate estimates of genetic corre-lations between each pair of conditions. Heritability estimates of fracture, osteoarthritis, suspensory ligament and tendon injury were small to moderate (range: 0.01-0.20). Fracture was found to be positively genetically correlated with both osteo-arthritis and suspensory ligament injury. These results suggest that there is a significant genetic compo-nent involved in the risk of the studied conditions. Due to positive genetic correlations, a reduction in prevalence of one of the correlated conditions may effect a reduction in risk of the other condition. [ABSTRACT FROM AUTHOR]

Enhanced understanding of reasons for, and timings of, mortality in Thoroughbreds prior to entering race training is warranted to provide insight into this population's health status. The aims of this study were to describe pathologies diagnosed at post-mortem (PM) examination in Thoroughbreds aged from birth to 18 months and investigate associations between age and pathology. Reports from a pathology laboratory in Newmarket, UK, were used to identify eligible cases examined between January 2006 and December 2020. Reported pathologies were extracted and categorised where appropriate. Comorbidities and pathogens identified were reported where available. Associations between age and selected pathologies were assessed using logistic regression. Of 144 eligible Thoroughbreds presented for PM, 137 had an available report and pathologist's diagnosis. Congenital defects were most commonly reported (20%; n = 28/137; 95%CI 15–29), 69% of which (n = 19/28; 95%CI 49–82) were conformational manifestations of developmental orthopedic disease (DOD). Pneumonia was an important pathology (14%; n = 20/137; 95%CI 36–53) during the pre-weaning period, where Rhodococcus equi was identified in 50% (n = 10/20; 95% CI 29–70) of cases. Odds of congenital defects (OR 56.6; 95%CI 7.0–460.0; P < 0.001) were significantly greater in horses aged 0–2 days compared to 4–18 months at PM. Odds of pneumonia (OR 4.3; 95%CI 1.1–1.7; P = 0.04) were significantly greater in horses ages 1–4 months compared to 0–2 days at PM. This study shows that conformational manifestations of DOD are an important contributor to perinatal mortality, and that pathologies reported at PM vary with age in young Thoroughbreds. • Post-mortem findings from young Thoroughbreds are described. • The majority of cases presented in the neonatal period. • Congenital limb defects were an important contributor to perinatal mortality. • Rhodococcus equi was an important pathogen, particularly in pre-weaning pneumonia. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dual adjuvanted inactivated vaccine elicited superior humoral response. [•] 39% of weanlings failed to seroconvert following V1. [•] Increase in IFN-γ gene expression peaked at 7 days post V1. [•] No significant difference in IFN-γ gene expression elicited by different vaccines. [•] IL-4 gene expression greatest in weanlings vaccinated with ISCOM subunit vaccine. [Copyright &y& Elsevier]

It has been observed that microbubbles may pass through the pulmonary circulation of dogs and humans during exercise. In humans, this phenomenon has been associated with lower pulmonary artery pressures, enhanced right ventricular function and greater exercise capacity. In the exercising Thoroughbred horse, extraordinarily high cardiac outputs exert significant pulmonary vascular stresses. The aim of this study was to determine, using contrast echocardiography, whether Thoroughbred horses performing strenuous exercise developed pulmonary transit of agitated contrast microbubbles (PTAC). At rest, agitated contrast was observed in the right ventricle, but not in the left ventricle. However, post-exercise microbubbles were observed in the left ventricle, confirming the occurrence of PTAC with exercise but not at rest. Further investigation is warranted to investigate whether this phenomenon may be associated with superior physiology and performance measures as has been implicated in other species. [ABSTRACT FROM AUTHOR]

The relationship between osteoarticular status and future athletic capacity is commonly accepted in equine practice, but there is little to support this belief in Thoroughbreds. The objective of this study was to assess the prevalence of juvenile osteochondral conditions (JOCC) in Thoroughbred yearlings and to investigate the significance of these with regard to subsequent racing performance. The radiographic files from 328 Thoroughbred yearlings born in Normandy were assessed in a consistent manner and entered into a database together with racing records. Logistic regression models were used to quantify the association between each radiographic parameter and racing performance (raced/not raced, placed/not placed, performer/not performer) at 2, 3, 4 and 5years of age. The front fetlock (30.2% of horses), the dorsal aspect of the hind fetlock (18%), the carpus (15.9%) and the distal part of the hock (15.5%) were the most commonly affected joints. Most horses (87.5%) raced either in turf flat races or in hurdle races. Starting a race at 2years old was more frequent for yearlings without radiographic findings (RF) on the carpus or with less than one RF of moderate severity. The proportions of horses placed at 3years old decreased with increasing number or severity of RF. In racing horses, there was no association between the presence of RF and earnings. The radiographic score, calculated as the sum of all the severity indices found on the radiographic file of the horse appeared well correlated with performance. Using this synthetic index might help veterinarians to evaluate radiographs of Thoroughbred yearlings for potential buyers. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify exercise-related risk factors for carpal and metacarpo- and metatarso-phalangeal (MCPJMTP) joint injury occurrence in young Thoroughbreds in fiat race training. In a 2-year prospective cohort study, daily exercise and joint injury data were collected from horses in 13 training yards in England. Four injury categories were defined: (1) localised to a carpal or MCP/MTP joint based on clinical examination and/or use of diagnostic analgesia with no diagnostic imaging performed; (2) localised to a carpal or MCP/MTP joint with no abnormalities detected on diagnostic images; (3) abnormality of subchondral bone and/or articular margin(s) identified using diagnostic imaging; (4) fracture or fragmentation identified by diagnostic imaging. Multivariable Cox regression analysis was con- ducted to determine risk factors for injury occurrence, by type (carpal or MCP/MTP) and category. Exercise distances at canter and high speed in different time periods were modelled as continuous time-varying variables. A total of 647 horses spent 7785 months at risk of joint injury and 184 injuries were recorded. Increasing daily canter distance reduced the risk of Category 1 and Category 3 injuries whereas greater 30-day canter distances increased Category 4 injury risk. More weekly high-speed exercise increased Category 1 injury risk. MCP/MTP injury risk reduced with increasing daily canter distance but increased with accumulation of canter or high-speed exercise since entering training, whereas accumulation of canter exercise was marginally associated with reduced carpal injury risk. Risk of all injury types varied significantly between trainers. The results of this study suggest that regular canter exercise is generally beneficial for joint health, while accumulation of high-speed exercise detrimentally affects MCPJMTP joints. [ABSTRACT FROM AUTHOR]

Abstract: Abrupt dietary transitions and feeding of rapidly fermentable diets are common practices in the horse industry and have been associated with digestive and metabolic disorders that can impair the performance of horses. The present study investigated the effect of dietary transition from pasture grazing to confinement with concentrate feeding, and back, on fecal pH and bacterial populations of Streptococcus spp and Lactobacillus spp. Six Thoroughbred fillies, previously grazing perennial ryegrass and white clover-based pasture, were housed in individual stalls and fed an increasing ratio of concentrate to conserved forages for 13 days (days 1-13), followed by an abrupt transition back to only pasture-grazing for 3 days (days 14-16). The concentrate was initially offered at 0.83 kg dry matter (DM)/d and increased to 5 kg DM/d, whereas ensiled alfalfa was initially offered at 0.61 kg DM/d, increasing to 1.22 kg DM/d. Meadow hay was initially offered at 6.73 kg DM/d, decreasing to 1.6 kg DM/d. Fecal specimens were collected daily for determination of pH, and every 2 days for quantitative analysis of Streptococcus spp and Lactobacillus spp. Mean fecal pH increased significantly from pasture baseline values (pH 6.18) during the initial confinement and supplementation on day 1 (6.37), day 2 (6.52), day 3 (6.58), and day 4 (6.43) (standard error of mean [SEM]: 0.056; P < .001). By day 5, mean fecal pH values had decreased to, and remained at, baseline values until the horses returned to pasture, when another increase occurred at day 15 (6.45). Fecal colony forming units (cfu) of Streptococcus spp and Lactobacillus spp increased linearly (r = 0.94; P < .001) from 6.0 and 6.1 log10 cfu/g on day -4, to 7.8 log10 cfu/g on day 14 (SEM: 0.2 P < .001), respectively. Fecal cfu decreased on return to a pasture-only diet (P < .001). In this study, the increment of bacterial populations was associated with a relatively stable fecal pH and highlights the difficulty in identifying the effects of dietary transition on the equine hindgut health, without microbial culture. [Copyright &y& Elsevier]

Abstract: Stereotypies are considered a cause and symptom of impaired welfare, and have been associated with suboptimal husbandry systems. The aim of this study was to estimate the prevalence of stereotypic and other abnormal behaviors in Chilean thoroughbreds by direct observation, and examine their associations with biological characteristics and management practices. Seven hundred forty-three racehorses were observed directly, every 5 minutes during 1 hour before and after feeding, to identify behavioral disorders. A questionnaire was administered to handlers to obtain information about the animal and husbandry practices. The total observed prevalence rate of horses with one or more abnormal behavior was 11.03%. The total observed prevalence rates of stereotypies and abnormal behaviors were 6.32% and 5.52%, respectively. Horses at racetrack B presented more abnormal behaviors than those at racetrack A (P = .0092), and specifically, the prevalence of the oral group was higher (P = .0013). Mares presented a higher percentage of stereotypies (P = .0014), and the use of wood shaving bedding was positively associated with abnormal oral behaviors (P = .0027). Visual contact with conspecifics was possible for 86% of horses; the remaining had no social contact. Their diet consisted of a mixture of 71% of oats and 29% of roughage in average, presented between one and three times daily. No significant associations were found between the presence of visual contact, number of daily rations, yard, and percentage of roughage delivered, and stereotypy presentation (P > .05). In 43% of the cases with stereotypy, horses were impeded from performing the behavior by physical methods, avoiding the real problem and acting as a risk for animal welfare. [Copyright &y& Elsevier]

Abstract: The aim of the study was to analyse the pedigree information of Thoroughbred horses which were participating in gallop races between 1998 and 2010 in Hungary. Among the 3043 individuals of the reference population there were imported animals from foreign countries (e.g. Germany, England or Ireland) and horses that were born in Hungary. The number of complete generations was 15.64 (varied between 0 for the founders and 25.20), the mean number of full generations was 6.69, and the mean maximum generations were 28.96. The number of founders was 1062, and the effective number of founders was 42. Two hundred and thirty-two founders were born before 1793 (when the stud book of the Thoroughbred breed was closed), therefore these founders are considered as true founders of the breed. These 232 founders were responsible for 88.58% of the gene pool in the reference genome. The significant difference between the number of founders and effective number of founders indicate that the genetic diversity decreased greatly from the founders to the reference population. The number of ancestors was 908 and only 6 of them were responsible for 50% of the genetic diversity in the examined population. The effective number of ancestors was 15.32. From the ratio of the effective number of founders and effective number of ancestors we concluded to a bottleneck effect that characterizes the pedigree under study. Generation interval was more than a year longer for stallions (12.17) than it was for mares (10.64). More than 94% of the individuals in the pedigree were inbred, and the average inbreeding of the population was 9.58%. Considering the changes of the inbreeding status of the examined population 4 large time periods were appointed. The first lasted until 1780, the second period was from 1780 until 1952, the third period was between 1946 and 1998 and the last one was from 1998 until 2008. Rate of inbreeding in the last generation was 0.3%, which forecasts further increase in inbreeding. The effective population size was above 100 in the last 30 generations, proving the genetic diversity did not decrease by a level that would make long-term selection impossible. [Copyright &y& Elsevier]

Abstract: Controversial results on lipid utilization as an energy source during training in horses are found in the literature. The objective of this study was to assess blood lipid profile during different training programs in horses. Seventeen Standardbred horses (400 ± 50 kg) and 17 Thoroughbred horses (380 ± 15 kg) followed different training programs. Blood lipid profile, including triglycerides (TGs), total cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL), was analyzed, and very-low-density lipoprotein (VLDL) concentration was calculated. Data were analyzed using Student t test, and linear regressions were done. Cholesterol and LDL decreased during training programs in Standardbred trotters (P = .0001 and P = .0053, respectively), and VLDL was found to be close to the significance level (P = .053). Blood lipid profile, including TGs (P = .0014), cholesterol (P = .0057), HDL (P = .0128), LDL (P = .0091), and VLDL (P = .0014), varied throughout the training program in Thoroughbred horses. Negative slope of blood lipids and positive slope of TG linear regression in Standardbred trotters were significant for all parameters (P ≤ .05), whereas cholesterol and LDL regression showed poor P and r 2 values and HDL P value was slightly above the significance level (P = .069) in Thoroughbred horses. TGs and VLDL showed a positive linear trend in Thoroughbred horses (P = .002). Exercise and different training programs lead to significant variations of lipid profile and lipid utilization in horses. Lipid utilization as an energy source improved with training in Standardbred trotters, whereas this was not the case in Thoroughbred horses. Further studies on the effect of training programs using different conditions and horse breeds would be necessary to understand lipid utilization as an energy source in athletic horses. [Copyright &y& Elsevier]

The objective of this study was to detect and characterize latent equine herpes virus (EHV)-l and -4 from the submandibular (SMLN) and bronchial lymph (BLN) nodes, as well as from the trigeminal ganglia (TG) of 70 racing Thoroughbred horses submitted for necropsy following sustaining serious musculoskeletal injuries while racing. A combination of nucleic acid precipitation and pre-amplification steps was used to increase analytical sensitivity. Tissues were deemed positive for latent EHV-1 and/or -4 infection when found PCR positive for the corresponding glycoprotein B (gB) gene in the absence of detectable late structural protein gene (gB gene) mRNA. The EHV-1 genotype was also determined using a discriminatory real-time PCR assay targeting the DNA polymerase gene (ORF 30). Eighteen (25.7%) and 58 (82.8%) horses were PCR positive for the gB gene of EHV-1 and -4, respectively, in at least one of the three tissues sampled. Twelve horses were dually infected with EHV-1 and -4, two carried a latent neurotropic strain of EHV-1, six carried a non-neurotropic genotype of EHV-1 and 10 were dually infected with neurotropic and non-neurotropic EHV-1. The distribution of latent EHV-1 and -4 infection varied in the samples, with the TG found to be most commonly infected. Overall, non-neurotropic strains were more frequently detected than neurotropic strains, supporting the general consensus that non-neurotropic strains are more prevalent in horse populations, and hence the uncommon occurrence of equine herpes myeloencephalopathy. [ABSTRACT FROM AUTHOR]

Abstract: Records (years 2005–2007) were analyzed from a Thoroughbred stud farm in central Kentucky. Data from all breeding cycles of foaling mares were tabulated (3184 cycles of 2003 foaling mares bred between 7 and 163 days postpartum). A multiple logistic regression model employing Bayesian statistics was used to adjust for factors that significantly affected outcome; odds ratios (ORs) for pregnancy rate, pregnancy loss rate, and foaling rate were determined to examine the influence of day of postpartum breeding on these parameters. Mares bred before Day 22 (Day 0 = day of foaling) postpartum had a decreased OR for becoming pregnant (P < 0.05); the median OR for becoming pregnant (1.00) was not reached until Day 46 postpartum. Mares bred before Day 13 postpartum had an increased OR for pregnancy loss (P < 0.05). The median OR for pregnancy loss did not decline below 1.00 until Day 78 postpartum. Mares bred before Day 20 postpartum had a decreased OR for producing a foal (P < 0.05). The median OR for producing a foal (1.00) was not reached until Day 75 postpartum. We concluded that fertility (in terms of a higher OR for becoming pregnant and a lower OR for pregnancy loss, resulting in a higher OR for producing a foal) continued to improve in Thoroughbred mares for approximately 2.5 mo postpartum. These findings are of importance to management strategies directed at early postpartum breeding, and explain some of the reported drift in subsequent foaling dates of Thoroughbred mares, despite management practices that employ early postpartum breeding. [Copyright &y& Elsevier]

Abstract: Many racing authorities, sales companies and equestrian bodies have mandatory vaccination policies for equine influenza (EI). The consequences of lack of vaccine efficacy include clinical disease, disruption to training programmes, the cancellation of equestrian events and the introduction of virus to susceptible populations. The correlation between antibody against the virus haemagglutinin and protection against influenza has been well established. The objective of this study was to compare the antibody responses of 66 unvaccinated Thoroughbred weanlings on four different stud farms, following primary vaccination (V1, V2 and V3) with the five EI vaccines commercially available in Ireland (Duvaxyn IET Plus, Equilis Resequin, Equip FT, Equilis Prequenza Te, ProteqFlu Te). Antibody responses were monitored for 6 months post V3 by single radial haemolysis. The pattern of antibody response was similar for all vaccines and for all antigens tested. A rapid decline of antibody level was observed by 3 months post V2 for all vaccines. The antibody response of the horses vaccinated with the whole virus vaccine Duvaxyn IET Plus was significantly higher than that of the horses vaccinated with the other four products. Five weanlings had maternally derived antibodies (MDA) at the time of V1. The canary pox recombinant vaccine, subunit vaccine and whole virus inactivated vaccines administered to these weanlings did not induce a detectable antibody response against the background of MDA but effectively primed the animals as revaccination resulted in a strong antibody response. In this study 43% of the weanlings failed to seroconvert after V1. This high incidence of poor responders has not been reported in previous experimental studies relating to these products. The poor responders were observed in all vaccine groups except those vaccinated with Duvaxyn IET Plus. Post V2 the incidence of poor responders was reduced to 7% and all horses responded to V3. The study demonstrates that independent evaluation of influenza vaccine performance in the field is critical to add to the body of knowledge gained from experimental challenge experiments carried out for regulatory or marketing purposes. [Copyright &y& Elsevier]

Abstract: This study was conducted to estimate the annual genetic and environmental trends of Thoroughbred racehorses. A total of 208,043 records collected from horses that raced at Gwacheon racecourse were analyzed. The average generation intervals of the sires of offspring and the dams of offspring were 10.82 and 10.31years, respectively. The effects of the contemporary groups accounted for more than approximately 44% of the total variation in finish time and were the most important environmental effects in the genetic evaluation model. The range of estimated heritabilities and repeatabilities were from 0.06 to 0.30 and from 0.31 to 0.59, respectively. The estimate of heritability was highest at the racing distance of 1000m (0.30), and decreased as the racing distance increased. Of the total variance components, the proportion of variance due to the jockey was from 0.02 to 0.06, and it was larger in longer distance races than in shorter ones. According to the results, racehorses accounted for 94.8%, and the jockey for only 5.2%, of finish time. As the racing distance increased, the percent contribution of the jockey also tended to increase. The phenotypic and environmental improvements were −2.140 and −1.492s over 16years studied, respectively. On the other hand, genetic gains in racing performance of home-produced and imported racehorses in the same period were −0.459 and −0.369s, respectively. The genetic improvement of racehorses in racing performance was very consistent, resulting in average gains of −0.029 and −0.031s per year in home-produced and imported racehorses, respectively. [Copyright &y& Elsevier]

Musculoskeletal injury is the most common cause of lost training days in the young Thoroughbred horse in flat race training. To date, there has been little investigation of the regional patterns of injury frequently observed by clinicians in racehorse practice. The present study was conducted to determine incidence of musculoskeletal injuries in Thoroughbreds in training in Newmarket, United Kingdom. Veterinary records for all horses resident in three large (>100 horse) training yards were assessed for occurrence of significant musculoskeletal injury. A total of 248 injuries were recorded in 217 individual horses, from a total population of 616 individual horses; fractures of the tibia (20.7%) and proximal phalanx (14.5%) were the most common. Overall injury rates were similar between yards (23-26%/year), with seasonal patterns noted for some injury types. Incidence of certain injuries (P1, metacarpal/metatarsal condylar, pelvic fractures, and superficial digital flexor tendonitis) varied between yards. The majority of carpal, P1 fracture and SDF tendonitis cases were right-sided. [ABSTRACT FROM AUTHOR]

Abstract: Selection of proper phenotypic trait among various traits related with interesting performance plays an important role in genetic evaluation. In this study, principal components analysis (PCA) was adapted to generate a new index as a measure of racing performance of 12,279 horses. This method allows us to reduce the number of variables considered in the evaluation of the horses'' racing performance, which may facilitate modeling genetic programs. The resulted racing time, earning prize and rank were selected for generating new indices as the representation of racing performance of the horses. Three indices used in this study were: 1) PCA1 generated from the modified values of racing time, earning prize and rank, 2) PCA2 generated from the modified racing time and rank, and 3) the adjusted racing time. The first principal components (PCs), elements in the eigenvector corresponding to the largest eigenvalue of PCA, of PCA1 and PCA2 explained the variance of the selected variables about 75.6% and 75.4% respectively. Linear combinations of the first PCs and adjusted variables were used as new performance indices. Those animal models were composed of significant explanatory variables selected by Akaike information criterion (AIC). Heritability and repeatability were 0.324 (±0.026) and 0.334 (±0.034) for adjusted racing time, 0.319 (±0.014) and 0.326 (±0.018) for PCA1, and 0.324 (±0.010) and 0.332 (±0.012) for PCA2 respectively. Estimated heritabilities and repeatabilities for three indices showed similar values for domestic racing records. However, models using PCA showed better fitting for data than model using racing time as a performance index. The proposed methodology is efficient to evaluate the total variance in this group of correlated traits, allowing reduction in the number of variables for genetic evaluation and construction of better fitting model. [Copyright &y& Elsevier]

The purpose of this study was to gain evidence on the prevalence of dental abnormalities in stable-kept horses in comparison with free-living horses. It is expected that free-living horses that graze for as much as 16 h/day will have fewer dental abnormalities than stable-kept horses. In this study, the latter group was fed a diet that was based on a relatively high-energy, cereal-based feed. This was thought to be a representative of common practice in domesticated, stable-kept horses. Compound diets such as this have previously been shown to increase the frequency of chewing cycles and decrease mediolateral excursion. The occurrence of 10 named dental abnormalities present in the dentition of 60 Thoroughbred-type horses was recorded. Half of the population was at grass all year round in New South Wales, Australia. The remainder were stabled for 24 h/day in Gloucestershire, UK. All horses were between 5 and 15 years of age. The same, experienced, equine dental technician examined all horses using a full-mouth speculum and produced a routine dental chart. Stable-kept horses had a significantly higher total occurrence of abnormalities (P < 0.001) than free-living horses. The stable-kept group had a significantly higher prevalence of exaggerated transverse ridging across the occlusal surface of the cheek teeth, focal or ramped overgrowths of the cheek teeth and periodontal disease (P < 0.01 in all cases). All horses in both groups had some occurrence of sharp edges of the buccal and lingual edges of the cheek teeth. The results are in agreement with anecdotal evidence that a fibre-based, grazed diet results in fewer dental abnormalities. However, sharp edges may occur even with what is perceived as a 'natural' diet. [ABSTRACT FROM AUTHOR]

Abstract: The results of 3 years (2005–2007) of observations and mating (5,646 estrous cycles of 3,788 mares bred to 1 of 15 stallions) at one Thoroughbred breeding farm in central Kentucky were analyzed by a multiple logistic regression model using Bayesian statistics to evaluate the relationship between data entries (factors) and pregnancy outcomes. Factors found to be significantly (P < .05) associated with pregnancy outcome included stallion (one stallion had lower OR for pregnancy higher odds ratio [OR] for pregnancy, and one had, than other stallions), date of mating (OR for pregnancy declined slightly in May – July), mare age (OR for pregnancy were higher for mares <13 years old, and lower for mares >18 years old), mare beginning status (foaling mares had a higher OR for pregnancy), mating on foal heat (lowered OR for pregnancy), mating of the day for the stallion (OR for pregnancy was 4.16 times lower for fifth compared with first mating of day), reinforcement breeding (increased OR for pregnancy), dismount semen neutrophil score (lowered OR for pregnancy when neutrophils were present in dismount semen samples), and tranquilization before breeding (lowered OR for pregnancy in foaling and barren mares). The influence of dismount sample sperm motility scores on OR for pregnancy was weak, so motility scores were not included in the final logistic regression model. The majority of variation in pregnancy outcome was because of mare factors, with only approximately one-third of the variation in fertility explained by stallion. [Copyright &y& Elsevier]

Abstract: Sixty-seven million pounds of horsemeat derived from American horses were sent abroad for human consumption last year. Horses are not raised as food animals in the United States and, mechanisms to ensure the removal of horses treated with banned substances from the food chain are inadequate at best. Phenylbutazone (PBZ) is the most commonly used non-steroidal anti-inflammatory drug (NSAID) in equine practice. Thoroughbred (TB) race horses like other horse breeds are slaughtered for human consumption. Phenylbutazone is banned for use in any animal intended for human consumption because it causes serious and lethal idiosyncratic adverse effects in humans. The number of horses that have received phenylbutazone prior to being sent to slaughter for human consumption is unknown but its presence in some is highly likely. We identified eighteen TB race horses that were given PBZ on race day and sent for intended slaughter by matching their registered name to their race track drug record over a five year period. Sixteen rescued TB race horses were given PBZ on race day. Thus, PBZ residues may be present in some horsemeat derived from American horses. The permissive allowance of such horsemeat used for human consumption poses a serious public health risk. [Copyright &y& Elsevier]

Abstract: In Thoroughbred breeding, it is sometimes necessary to tranquilize a maiden mare to accomplish safe breeding by natural service. To determine whether tranquilization adversely affected fertility of maiden mares, pregnancy rates achieved in 792 matings of 531 maiden Thoroughbred mares were evaluated. One hundred sixty-three matings were accomplished after administration of a tranquilizer cocktail (20 mg acepromazine, 100 mg xylazine, and 10 mg butorphanol tartrate, injected intravenously), whereas 598 matings were accomplished without tranquilization. Pregnancy rate/cycle did not differ between maiden mares tranquilized before (64%; 105/163) and mares not tranquilized before mating (69%; 434/629) (χ2 = 1.048; P > .05). We concluded that tranquilization of maiden Thoroughbred mares immediately before mating did not adversely affect fertility. [Copyright &y& Elsevier]

This study aimed to determine the effects of exercise on racecourse performance in horses racing on the flat. Daily exercise and race records were obtained over a 2-year period for a cohort of racehorses in training for which injury data were also available. Multivariable regression techniques were used to investigate associations between canter, training gallop and race distances accumulated in the 30 days prior to each race and the odds of winning the race, earning prize money and the amount of prize money won. Higher cumulative high-speed (gallop + race) distances were associated with increased likelihood of winning a race and earning prize money. Having raced in the previous 30 days increased the odds of winning. There was an interactive effect of distance cantered and galloped during training on amount of prize money won, which was also associated with distance raced in the previous 30 days. Taken together with findings from previous injury studies in the same study population, these results indicate that training regimens designed to reduce skeletal injuries are unlikely to adversely affect race performance. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to compare racing performance before and after prosthetic laryngoplasty for treatment of laryngeal hemiplegia in inexperienced (horses without at least one start before surgery) and experienced (horses with at least one start before surgery) Thoroughbred and Quarter Horse racehorses. Medical records of 54 Thoroughbred and 18 Quarter Horse racehorses or horses intended for racing treated with prosthetic laryngoplasty and unilateral ventriculectomy for laryngeal hemiplegia were reviewed. Signalment, age at the time of surgery, resting endoscopic grade of laryngeal function, surgical procedure, and type of suture were recorded. Median performance index (PI), earnings, distance, and Beyer speed figure (BSF) per start for three races before and after surgery were compared, and factors associated with improved postsurgical performance were evaluated. Seventy-three percent of horses that had not raced before surgery and 84% of horses that competed in at least one race before surgery were able to return to racing after surgery. Fifty-nine percent and 27% of Thoroughbreds and Quarter Horses, respectively, were able to improve their PI after surgery. Sixty-two percent and 20% of Thoroughbreds and Quarter Horses, respectively, significantly increased their distance after surgery. Additionally, 61% and 66% of racehorses were able to increase their earnings and BSF after surgery, respectively. Horses treated with laryngoplasty and unilateral ventriculectomy have a good prognosis for return to racing. Inexperienced racehorses have a better prognosis for improvement after surgery than do experienced racehorses. Thoroughbred racehorses have a better success rate than Quarter Horse racehorses. [Copyright &y& Elsevier]

Abstract: Horse racing is a contest between horses, usually held for the purpose of betting. Thoroughbred horse racing is the most diffused form of horse racing throughout the world. Thoroughbred is one of the most versatile of horse breeds and has influenced the development of many other breeds. Thoroughbred horses served as a foundation stock for the development of the light horse breeds. The two types of horse racing are flat racing and jumping races/steeplechases. The measures of racing performance are broadly classified into three categories. They are time and its several variations, handicap or similar performance ratings and earnings. One common measure of the performance of racehorses evaluated genetically is racing time or final time. The heritability estimates differed according to method of estimation, age, sex, track and distance. Time measure generally had a heritability in the range of 0.1 to 0.2 with the higher values for shorter races. For handicap and earning measures the heritabilities reported were generally higher in the range of 0.3 to 0.4; hence these may be considered in genetic evaluation of racing performance of Thoroughbred horses. The average generation interval of Thoroughbred horses was 11.2±4.5 and 9.7±3.8 years for males and females respectively, which limits the genetic progress in racing horses. However, the major advantage is that the racing performance may be evaluated in both males and females and repeated observations can be obtained on the same animal in relatively short periods. These factors coupled with the reasonable heritability of some measures of racing performance, suggest that mass selection based on performance tests would be the selection procedure of choice to improve the racing performance of Thoroughbred horses. In general, the inbreeding at the rate that is usually practised in Thoroughbred population does not enable much gene fixing. However, practice of close inbreeding may be avoided, even though it still fascinates breeders at subconscious level. [Copyright &y& Elsevier]