Racing Performance Research Articles

Performance in Mixed-Sex and Single-Sex Tournaments: What We Can Learn from Speedboat Races in Japan

In speedboat racing in Japan, women racers participate and compete in races under the same conditions as men, and all individuals are randomly assigned to mixed-gender or single-gender groups for each race. In this paper we use a sample of over 140,000 observations of individual-level racing records provided by the Japanese Speedboat Racing Association to examine how male-dominated circumstances affect women's racing performance. We control for individual fixed-effects plus a host of other factors affecting performance (such as starting lane, fitness and weather conditions). Our estimates reveal that women's race-time is slower in mixed-gender races than in all-women races, whereas men racer's time is faster in mixed-gender races than men-only races. In mixed-gender races, male racers are found to be more - as proxied by lane-changing - in spite of the risk of being penalized if they contravene the rules, whereas women follow less aggressive strategies. We find no difference in disqualifications between genders. We suggest that gender-differences in risk-attitudes and over-confidence may result in different responses to the competitive environment and penalties for rule-breaking, and that gender-identity also plays a role.

MSTN, CKM, and DMRT3 Gene Variants in Different Lines of Quarter Horses

Single nucleotide polymorphisms (SNPs) in the equine myostatin (MSTN) (g.66493737C>T) and creatine kinase muscle (CKM) (g.22999655C>A) genes have been associated with optimum racing distance and muscle development and racing performance in Thoroughbred horses, respectively. Considering that, since its formation, the Quarter Horse breed has received important genetic influence from the English breed, the genes cited become important candidates for athletic performance in the racing line of the American breed. An SNP in the equine doublesex and mab-3-related transcription factor 3 (DMRT3) gene (g.22999655C>A) has been described, which is responsible for the gait phenotype in homozygous individuals. Using a sample of 296 Quarter Horses of the racing line and 68 animals of the cutting line, the objective of this study was to compare the frequencies of the three SNPs cited above between a random subsample of animals of the cutting line (n = 20) and animals with extreme phenotypes for racing performance (n = 20 per extreme phenotype). The MSTN SNP showed practically no variation, with the observation of only one heterozygous animal (CT) in the cutting line, suggesting that this gene has been under great selective pressure within the racing segment. The CKM gene variant studied was found to be polymorphic, but no significant associates were observed between its alleles and the different lines or groups. Two animals carrying the CA heterozygous DMRT3 genotype were identified in the group with poor racing performance and one in the cutting line, indicating that this variant can be a limiting factor for the development of greater speeds.

Different DMRT3 Genotypes Are Best Adapted for Harness Racing and Riding in Finnhorses.

Previous studies showed a positive effect of the DMRT3 "gait keeper" mutation on harness racing performance in Standardbreds, French-, and Nordic trotters. The mutation has also been shown to influence riding traits in multiple breeds. This study investigated the effect of the DMRT3 mutation on harness racing performance and riding traits in Finnhorses. Finnhorses used for harness racing (n = 180) and for riding (n = 59) were genotyped for the DMRT3 mutation. For the trotters the genotypes were evaluated for association with racing performance (number of starts, victories, placings, earnings, and race times). At 3-6 years of age the AA genotype was superior compared with the CA and CC genotypes. The AA horses had a significantly higher proportion of victories (P = 1.4×10(-6)) and placings (P = 4.1×10(-7)), better race times (P = 0.01), and earned more money (P = 0.009) compared with C-horses. For the Finnhorses used for riding the owners answered a questionnaire to score how well the horse performed the gaits walk, trot, and canter on a scale from 1 to 6. These scores were tested for association with the DMRT3 genotypes. Although AA horses were more successful as racehorses, the CC and CA horses appear more adapted for classical riding disciplines. The AA horses received significantly lower gait scores compared with C-horses for the majority of gaits. Except for rhythm in extended canter (P = 0.05), there were no significant differences between CA and CC horses. This study shows that there are different optimal genotypes for different disciplines and the DMRT3 mutation clearly influences gaits and performance in Finnhorses.

Comparison of Sequence Variants in the PDK4 and COX4I2 Genes Between Racing and Cutting Lines of Quarter Horses and Associations With the Speed Index

Different selection objectives within the Quarter Horse breed led to the formation of groups with distinct skills, including the racing and cutting lines. With a smaller population size in Brazil, but of great economic representativeness, the racing line is characterized by animals that can reach high speeds over short distances and within a short period of time. The cutting line is destined for functional tests, exploring skills such as agility and obedience. Although the athletic performance of horses is likely to be influenced by a large number of genes, few genetic variants have so far been related to this trait and this was done exclusively in Thoroughbreds, including the g.38973231G>A single-nucleotide polymorphism in the PDK4 gene and the g.22684390C>T single-nucleotide polymorphism in the COX4I2 gene. The results of the present study demonstrate the presence of polymorphic PDK4 and COX4I2 genes in Quarter Horses. The analysis of 296 racing animals and 68 cutting animals revealed significant differences in allele and genotype frequencies between the two lines. The same was not observed when these frequencies were compared between extreme racing performance phenotypes. There were also no significant associations between alleles of the two polymorphisms and the speed index. These results suggest that the alleles of the PDK4 and COX4I2 genes, which are related to better racecourse performance in Thoroughbreds, are probably associated with beneficial adaptations in aerobic metabolism and therefore play secondary roles in sprint racing performance in Quarter Horses, which is mainly anaerobic.

Determination of muscle mitochondrial respiratory capacity in Standardbred racehorses as an aid to predicting exertional rhabdomyolysis

This prospective cohort study evaluated the potential of high-resolution respirometry applied to permeabilized muscle fibers for fitness evaluation in French Standardbred racehorses.Fitness evaluation by means of respirometric parameters did not correlate with racing performance registered over the following racing season. However, altered mitochondrial energy metabolism was associated with higher risk of developing exertional rhabdomyolysis, a common cause of exercise intolerance in racehorses. These data represent a first step towards establishing reference values for muscle OXPHOS capacity in this breed.

Polymorphism in dopamine receptor D4 gene is associated with pigeon racing performance.

Sequencing and genotyping: Sequencing of PCR products (Table S1) covering the complete exon 3 and parts of introns 2 and 3 from the DRD4 gene revealed four SNPs: the intronic g.129954C>T (ss1751581452), two missense mutations g.129562A>C (p.Arg139Ser; ss1751581453) and g.129456C>T (p.Leu175Phe; ss1751581455) and the synonymous g.129484T>C (ss1751581454). The last one was not further considered. The study involved 123 racing pigeons derived from two unrelated pigeon flocks. SNP g.129562A>C and SNP g.129456C>T were in complete linkage disequilibrium, and only the latter was considered in association analyses. The frequencies of SNPs and of combined genotypes of the DRD4 gene are presented in Table S2.

Potential role of maternal lineage in the thoroughbred breeding strategy.

Many studies have focused on identifying the genes or single nucleotide polymorphisms associated with the athletic ability of thoroughbreds, but few have considered differences in maternal and paternal heritability of athletic ability. Herein, we report on our association study of career race performances of 675 Australian thoroughbreds with their pedigrees. Racing performance data (prize money per start) were collected from the Bloodhound database. The performance of all horses was categorised as either poor or elite athletic achievement. Then, 675 foals were divided by their parents' performance (elite or poor) into four groups: (1) elite dams and elite sires; (2) elite dams and poor sires; (3) poor dams and elite sires; and (4) poor dams and poor sires. The performance of foals was then compared between the four groups. The results show that the heritability of race performance between dams and foals (r = 0.141, P < 0.001) is much higher than that between sires and foals (r = 0.035, P = 0.366), and that this difference is statistically significant (P < 0.05). We also examined the effect of the child-bearing age of dams and sires on the ratio of elite foals. We found a strong correlation between the number of elite foals and dams' child-bearing age (r = -0.105, P < 0.001), with the ratio of elite offspring reaching a high level between a child-bearing age of 8 and 11 years (χ2 = 14.31, d.f. = 1, P < 0.001). These findings suggest that the maternal line may play an important role in the selective breeding of athletic performance in thoroughbreds.

36 The DMRT3 “Gait keeper” mutation affects harness racing performance and riding traits in Finnhorses

s / Journal of Equine Veterinary Science 35 (2015) 398e399 399 36 The DMRT3 “Gait keeper” mutation affects harness racing performance and riding traits in Finnhorses K. J€aderkvist*, L. Johansson , A. Mykk€ anen , M. M€aenp€ a€ a , L.S. Andersson , L. Andersson , T. Arnason , and G. Lindgren 1 1 Swedish University of Agricultural Sciences, Uppsala, Sweden; University of Helsinki, Helsinki, Finland; 3 Suomen Hippos ry, Espoo, Finland; Uppsala University, Uppsala, Sweden; 5 IHBC AB, Knubbo, Morgongava, Sweden The DMRT3 “Gait keeper”mutation is well known for its effects on gaits and locomotion patterns in horses. Previous studies have shown the mutation to have a strong favorable effect on harness racing performance in Standardbreds, French and Nordic trotters. The mutation also affects riding traits in Icelandic horses and in Standardbreds. The aim of this study was to investigate the effect of the DMRT3mutation on harness racing performance and riding traits in Finnhorses. We genotyped for the DMRT3 mutation 180 Finnhorses of trotting type and 59 Finnhorses used for riding. For the trotters the genotypes were evaluated for association with racing performance traits (number of starts, victories, placings, earnings and race times) at different ages. For the Finnhorses used for riding the owners answered a 12 question survey about their horse and had to score how well the horse performed the gaits walk, trot and canter on a scale from 1 to 6. T€ olt and pace ability was also reported. These scores were then tested for an association with the DMRT3 genotypes. Racing performance analyses were performed usingWald tests in PLINK. Fisher's exact tests in R were used for analyses on t€ olt and pace ability, while pairwise t-tests were used for gait score analyses. The results showed that the DMRT3 mutation strongly influenced racing performance in Finnhorses. Between 3 and 6 years of age AA horses had a significantly higher proportion of victories (P1⁄4 1.4 10 6) and placings (P 1⁄4 4.1 10 7) compared with Chorses. Additionally, they also had better race times (P 1⁄4 0.01) and earned more money (P 1⁄4 0.009). Despite CA horses not performing as well as AA horses, they still performed better than CC horses. Thus supporting an additive genetic effect of the DMRT3 mutation on racing performance. Similar results were found when comparing performance at different ages (4, 5, 6 and 10 years), except for 3 years of age where no significant differences were present. Although AA horses were more successful as racehorses, the Chorses appear more adapted for classical riding disciplines. This is supported by significantly lower gait scores for AA horses compared with Chorses for the majority of gaits. With the exception of rhythm in extended canter (P 1⁄4 0.05), no significant differences were present between CA and CC horses for gait scores. A significant association (P 1⁄4 0.006) between DMRT3 genotype and the ability to show t€ olt was present; however, no significant association was present for pace (P 1⁄4 0.21). This study shows that different genotypes are optimal for different disciplines and the DMRT3 mutation clearly influences the pattern of locomotion in Finnhorses.

Exercise induced pulmonary hemorrhage in horses: American College of Veterinary Internal Medicine consensus statement.

BackgroundPublished studies of exercise‐induced pulmonary hemorrhage (EIPH), when assessed individually, often provide equivocal or conflicting results. Systematic reviews aggregate evidence from individual studies to provide a global assessment of the quality of evidence and to inform recommendations.ObjectivesEvaluate evidence to determine: if EIPH adversely affects the health, welfare or both of horses; if EIPH affects the athletic capacity of horses; the efficacy of prophylactic interventions for EIPH; and if furosemide affects the athletic capacity of horses.AnimalsNone.Materials and Methods Systematic review. A panel of 7 experts was formed to assess evidence in the peer reviewed literature addressing each of the 4 objectives. Methodology followed that of the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). Publications were assessed for quality of evidence by working groups of the panel, and a summary of findings was presented in tables. Recommendations were based on quality of evidence and were determined by a vote of the panel.ResultsMuch of the evidence was of low to very low quality. Experimental studies frequently lacked adequate statistical power. There was moderate to high quality evidence that EIPH is progressive, is associated with lung lesions, that it adversely affects racing performance, that severe EIPH (Grade 4) is associated with a shorter career duration, that furosemide is efficacious in decreasing the incidence and severity of EIPH, and that administration of furosemide is associated with superior race performance.Conclusions and clinical significanceStrong recommendation that EIPH be considered a disease and a weak recommendation for use of furosemide in management of racehorses with EIPH.

Is there a place for thermocautery of the soft palate?

Is there a place for thermocautery of the soft palate?

Multiple Genes Related to Muscle Identified through a Joint Analysis of a Two-stage Genome-wide Association Study for Racing Performance of 1,156 Thoroughbreds.

Thoroughbred, a relatively recent horse breed, is best known for its use in horse racing. Although myostatin (MSTN) variants have been reported to be highly associated with horse racing performance, the trait is more likely to be polygenic in nature. The purpose of this study was to identify genetic variants strongly associated with racing performance by using estimated breeding value (EBV) for race time as a phenotype. We conducted a two-stage genome-wide association study to search for genetic variants associated with the EBV. In the first stage of genome-wide association study, a relatively large number of markers (~54,000 single-nucleotide polymorphisms, SNPs) were evaluated in a small number of samples (240 horses). In the second stage, a relatively small number of markers identified to have large effects (170 SNPs) were evaluated in a much larger number of samples (1,156 horses). We also validated the SNPs related to MSTN known to have large effects on racing performance and found significant associations in the stage two analysis, but not in stage one. We identified 28 significant SNPs related to 17 genes. Among these, six genes have a function related to myogenesis and five genes are involved in muscle maintenance. To our knowledge, these genes are newly reported for the genetic association with racing performance of Thoroughbreds. It complements a recent horse genome-wide association studies of racing performance that identified other SNPs and genes as the most significant variants. These results will help to expand our knowledge of the polygenic nature of racing performance in Thoroughbreds.

Prevalence of Radiographic Abnormalities of the Proximal Interphalangeal Joint of Young Thoroughbreds and Associations With Early Racing Performance

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.

Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses.

Exercise-induced pulmonary haemorrhage (EIPH) occurs commonly in Thoroughbred racehorses worldwide. While EIPH is believed to be an important cause of impaired performance in these horses, there is limited evidence from sufficiently powered studies to evaluate this association. To evaluate whether EIPH is associated with finishing position, distance finished behind race winners and differences in race earning among Thoroughbred horses racing in South Africa. Prospective cross-sectional study. One thousand Thoroughbred horses racing in South Africa were enrolled prior to a single race and underwent tracheobronchoscopic examination within 2 h of racing. Three observers, blinded to the horses' identity and race performance, independently evaluated EIPH occurrence and severity using video recordings of the examination. Data were analysed using multivariable logistic and linear regression while controlling for important horse and race factors as potential confounding variables. Overall, 68% of horses had evidence of EIPH (grade ≥1). Horses without evidence of EIPH (severity grade 0), when compared with horses with any evidence of EIPH (grade ≥1), were >2 times more likely to win races (odds ratio = 2.3; 95% confidence interval 1.4-3.7; P = 0.001), finished an average of one length ahead of horses with EIPH (P = 0.03), and were 2.5 times more likely to be in the highest decile in race earnings (odds ratio = 2.5, 95% CI 1.5-4.1, P<0.001). However, no association was identified regarding finishing in the top 3 positions or earning money when analysed as a continuous variable or analysed as any winnings vs. none. Exercise-induced pulmonary haemorrhage was associated with impaired performance in Thoroughbred racehorses not medicated with furosemide and not using nasal dilator strips. These findings provide strong corroboration of previous research indicating that the occurrence of EIPH has a major impact on the ability of Thoroughbred racehorses to compete successfully as elite athletes.

Musculoskeletal Injuries in Auto Racing: A Retrospective Study of 137 Drivers

Background and Purpose: The effect of continuous exposure of a driver's bones and muscles to vibration and G forces to years of automobile racing and the effect on overall health have not yet been examined in detail. The goal of this study was to investigate via questionnaire the musculoskeletal injuries and influencing parameters in 130 amateur and 7 professional race car drivers. Materials and Methods: A questionnaire, translated in English and German, was used to investigate the parameters that influence the racing performance and the character of resulting injuries. Results: This investigation involved 137 drivers (133 men and 4 women) with a mean age of 42 years (standard deviation = 15). Approximately half of the drivers had < 10 years of experience in auto racing (49%). The drivers mainly complained about pains in the lumbar (n = 36; 26%), shoulder (n = 27; 20%), and neck regions (n = 25; 18%). The driver's posture and the comfort of the seat were statistically significant for causing lower back and upper legs pains. The race duration was relevant to neck and shoulder discomfort. Conclusion: The high incidence of musculoskeletal injuries in race car driving indicates the need for further improvements. Elimination of driver complaints about pain in the spine and upper extremities can be achieved through technical development, as already accomplished in Formula One racing.

저가 입문용 1인승 레이스카 Tubular Space Frame의 비틀림 강성 최적설계

일반적으로 고성능의 레이스카나 스포츠카 시장에서 차량의 프레임 설계는 매우 중요한 기술적 요소로 작용하고 있다. 차량의 비틀림 강성은 차량의 코너링 성능에 많은 영향을 주기 때문에 레이스 차량에 있어 우수한 성능의 프레임이라는 것은 높은 비틀림 강성을 가진다는 것을 뜻한다. 본 연구에서는 입문용 포뮬러 레이스카 프레임의 최적 비틀림 강성 설계를 위하여 다구찌 직교배열표를 가진 실험계획법과 유한요소 해석 기술을 이용하였다. 이러한 기법을 통해서 얻은 결과가 초기설계단계에서 보다 14.5%의 무게를 감량함과 동시에 무게 대비 비틀림 강성 10.7%의 개선 효과를 볼 수가 있었다. 따라서 본 연구에서는 직교배열표를 가지는 실험계획법을 이용한 구조해석이 설계 초기단계에서 저가형 레이스 차량에 사용되는 Tubular space frame 설계에 매우 유용함을 나타내고 있다. 【Generally, the frame design of a vehicle is a critical technology that plays an important role in the racing and high performance sports car market. The high performance of race car frame means that it requires high torsional stiffness because it directly affects the cornering behavior of the race car. The optimal design for the frame of a low-cost single seat race car was carried out using the DOE (Design Of Experiments) with Taguchi's orthogonal array and FEM (Finite Element Method) analysis to secure sufficient torsional stiffness in this paper. According to the results by DOE and FEM analysis, the optimal design case produced improved 10.7% and 14.5% improvement in each stiffness-to-weight ratio and frame weight than in the early design step. Therefore, this paper shows that the optimal design with Taguchi's orthogonal array is very useful and effective for designing a tubular space frame of a low-cost single seat race car in the early design step.】

Analysis of Economic Loss Due to Equine Herpes Viral Infection

Equine herpes virus 1 and 4 is considered to be cause of rhinopneumonitis abortion in horses which can cause severe economic loss to the equine industry. Outbreaks of EHV-1 and 4 result in poor racing performance, cancellation of race entries, decreased revenue to the race tracks, mortality, closure or quarantine of stud farms and restrictions on the movement of horses. In the present study an attempt has been made to quantify the loss due to loss of work function among the equids in Tamilnadu. The models used in evaluation of economic impact of animal disease on production can be grouped under two headings namely statistical/epidemiological models and economic models. Out of the data collected from 184 respondents, 67.50 per cent (27 out of 40) and 32.50 percent (13 out of 40) of horses were utilized for anti-snake venom production and patrol respectively. 95.45 per cent (84 out of 88) and 4.45 per cent (4 out of 88) of ponies were utilized for transport and riding respectively. 100 per cent (17 out of 17) of mules were utilized for anti-snake venom production, 100 per cent (30 out of 30) of donkeys were kept as pack animals. One donkey and eight foals were kept without any work. It has been found that income loss due to loss of work function was 95.45 per cent (Rs. 1,47,000) in case of equids utilised for anti-snake venom production, 74.13 per cent (Rs. 1,200) in case of equids used for riding, 62.50 per cent (Rs. 200) in pack animals and 50.80 per cent (Rs. 1,200) in case of equids used for transport purpose (Table 3). The economic loss on account of equine herpes viral infection among the equids was quite high. The loss due to the loss of work function ranged from Rs. 200 to Rs. 1,47,000.

Treatment of osteochondrosis dissecans in the stifle and tarsus of juvenile thoroughbred horses.

To determine if arthroscopic surgery performed on weanlings/yearlings with trochlear ridge OCD of the femur (stifle OCD), or intermediate ridge of the tibia (tarsal OCD) detected on routine presale radiographs affects future racing performance. Retrospective case control study. Thoroughbred weanlings and yearlings. Stifle (N = 37; 22 male, 15 female) and tarsal (N = 35; 22 male, 13 female) OCD cases were identified. Outcome measures relating to racing performance (number of race starts, wins, places, and prize money earned, from races in their 2- and 3-year-old racing careers and in total from the period studied) were defined and then cases were compared to 2 age and sex matched controls using multilevel linear regression models. The effect of horse age at surgery and surgeon experience on the outcomes for cases with stifle OCD were also examined. Stifle OCD cases (N = 37; age 190-563 days at surgery) had significantly lower total earnings (P = .043), fewer total starts (P = .001) and fewer total 1st place finishes (P = .003) than their matched controls. For tarsal OCD cases (N = 35, age 127-470 days at surgery), fewer starts made by cases than controls (P = .018). Younger horse age at time of surgery and reduced surgeon experience were significantly associated with worse outcomes for stifle OCD cases. Stifle OCD cases appear to perform less successfully as racehorses than matched controls. Horse age at time of surgery has an effect on subsequent racing performance.

Racing performance in Standardbred trotting horses with proximal palmar/plantar first phalangeal fragments relative to the timing of surgery.

Proximal palmar/plantar osteochondral fragmentation of the first phalanx is a frequent radiographic finding in Standardbred horses. These lesions are routinely removed prior to the onset of a racing career with no evidence to support the timing of this surgical intervention. To determine whether horses racing before surgery slowed as they approached surgery date and whether they speeded up after surgery. To investigate the factors affecting whether a horse raced after surgery and compare the performance of horses that did and did not race before surgery. A retrospective study using 193 Swedish Standardbred trotters. Medical records and radiographs of each horse were examined. Racing data were retrieved from official online records. Generalising estimating equations were used to examine presurgery racing performance and determine whether this differed between horses that raced before surgery and those that had not. Multivariable regression was used to examine career earnings and number of career races. Horses racing before surgery neither slowed as they approached surgery, nor speeded up after surgery. Race speed of horses raced before surgery was not different from those that only raced after surgery. Racing before surgery was not associated with whether horses raced following surgery. Only horses with 3 affected legs had slower race speeds than other horses. No other horse level variables affected race speed, number of career races, career earnings or top speed. There was no significant difference in race speed between horses that raced before surgery and those that did not. Horses did not slow down prior to surgery. Horses with 3 affected legs ran slower than those with only a single or 2 affected limbs. There was no association between timing of surgery and race speed or career longevity. The potential benefits of surgical intervention should be critically examined.

Short- and long-term racing performance of Standardbred pacers and trotters after early surgical intervention for tarsal osteochondrosis.

Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature. To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC. Retrospective clinical study. The study population consisted of related, age-matched Standardbred racehorses (n = 278; 151 pacers, 127 trotters) with (n = 133) or without (n = 145) one or more tarsal OC lesions. All OC-affected horses were treated surgically prior to being sold as yearlings. Data obtained from publicly available race records for each horse included starts, wins, finishes in the top 3 (win, place or show), earnings and fastest time. Comparisons between OC-affected and unaffected horses were made for the entire population and within gaits. A smaller related population (n = 94) had these performance measures evaluated for their 2-5-year-old racing seasons. Osteochondrosis status was associated with few performance measures. Trotters were at higher risk for lesions of the medial malleolus but lower risk for lesions of the distal intermediate ridge of the tibia than were pacers. Horses with bilateral OC lesions and lateral trochlear ridge (LTR) lesions started fewer races at 2 years of age than those with unilateral lesions or without LTR lesions. Osteochondrosis seemed to have minimal effect on racing performance in this cohort, although horses with bilateral and LTR lesions started fewer races at 2 years. There was evidence for different distribution of OC lesions among pacers and trotters, which should be explored further. Standardbreds undergoing early removal of tarsal OC lesions can be expected to perform equivalently to their unaffected counterparts.

Sacroiliac Joint Morphology: Influence of Age, Bodyweight and Previous Back Pain

IntroductionDegenerative changes in sacroiliac joints (SIJ) are reported to cause poor performance in horses. The aim of this study was to document the frequency and nature of changes in SIJ surfaces of Thoroughbred (TB) racehorses and to correlate gross morphology and marginal new bone formation to age, body weight and history of back pain.MethodsSIJ surfaces from 37 deceased TBs retired from the Hong Kong Jockey Club were photographed and measurements taken to facilitate subjective and objective analysis of gross changes. SIJ surfaces were described, and the surface area of the joint surfaces determined from the photographs, using Image J. Area and shape of the joint surfaces were recorded and SIJs were graded and allocated a type according to pre‐determined criteria. Changes were compared for horses with and without clinical records of back pain.ResultsMean age was 6.6 ± 2.3 years; weight 494 ± 35 kg; with no differences between horses with (n = 14) and without (n = 23) a history of back pain. There was no relationship between bodyweight (r = 0.08) or age (r = 0.13) and SIJ surface area. SIJs of the back pain group were affected by obvious gross pathology that showed certain characteristics. There was a relationship between surface area of joint and degree of marginal bone formation (P&lt;0.001). SIJs from the group of TBs with no back pain had fewer and less obvious gross findings.ConclusionsClinical evidence of back pain, which may reasonably be expected to have affected the horse's racing performance, was associated with characteristic gross pathology of the SIJ.Ethical Animal ResearchEthical approval for animal use was obtained by the institutional animal ethics committee (University of Queensland) and Hong Kong ethics committee. The study was performed on material collected during post‐mortem examination. Explicit owner informed consent for participation in this study is not stated. Sources of funding: Rural Industries Research and Development Council, Australia. Competing interests: none.