The risk of severity of limb injuries in racing thoroughbred horses.

A retrospective study was carried out to identify factors which predisposed Thoroughbred horses to severe injuries, as compared to less severe injuries, while racing on New York Racing Association (NYRA) tracks during the period of January 1986 to June 1988. A severe injury was defined as an injury which led to humane destruction of the horse. A less severe injury was defined as a horse which didn't race within 6 months following a muscular, ligament, tendon, or skeletal injury on the racetrack. The data were obtained from the Horse Identification Department records kept by the Chief Examining Veterinarian of NYRA and included 55 severely injured horses and 245 less severely injured horses. Multiple logistic regression analysis was used to identify factors associated with the risk of severe injuries compared to less severe injuries in those horses. There was a significant association between track and the risk of severe injury (horses raced on Belmont and Saratoga were more likely to develop a severe injury compared to horses raced on Aqueduct Main). The track surface was also associated with the risk of severe injury (horses raced on a firm turf had a significantly lower risk of severe injury associated with the track was significantly modified by the track condition (horses raced at Belmont when it was muddy had a significantly increased risk compared to Aqueduct dirt). Horses were more likely to experience severe injury in the early part of the race (less than or equal to 6 furlongs) than the latter part of the race (greater than 6 furlongs). The risk of severe injury decreased with the age of the horse.     

Identification of risk factors for traumatic injury in the general horse population of north-west England, Midlands and north Wales

Reasons for performing study: Traumatic injuries are a major cause of morbidity and mortality in the horse and consequently pose a serious threat to horses' wellbeing. To date, there have been no published studies assessing the frequency of injuries in the general horse population of the UK. Objectives: To obtain information regarding husbandry management strategies and injury prevalence in horses aged ≤15 years, with the aim of identifying predisposing risk factors for injury. Methods: A postal questionnaire was distributed to a randomly selected sample of horse owners across north‐west England, Midlands and north Wales. Factors associated with injury were assessed using univariable and multivariable logistic regression analysis performed with the binary outcome variable defined as whether or not the horse had sustained an injury within the previous 12 months. Results: A usable questionnaire response rate of 68% (652/953) was achieved. Forty percent of horses had sustained a traumatic injury within the past year, of which 62% occurred in the field and 13% during ridden exercise. Factors identified as being associated with an increased risk of traumatic injury included the following: breed other than cob or pony (P = 0.001), shorter duration of ownership (P = 0.002), being turned out with an increasing number of horses (P = 0.001), being used for competitive (P = 0.001) or Parelli (P = 0.006) purposes. Stabling at all times during the spring (P = 0.005), the use of wood fencing in paddocks (P = 0.05) and being prone to becoming distressed if left alone in a field (P = 0.04) were also found to be associated with an increased risk of injury. Stabling at all times during winter was associated with a decreased risk of injury (P = 0.006). Conclusions and potential relevance: Risk factors for sustaining injuries have been identified in association with management practices. This information may be used to educate owners regarding management of their horse(s) in order to prevent injury.     

Results of physical inspection before races and race-related characteristics and their association with musculoskeletal injuries in Thoroughbreds during races.

OBJECTIVE: To estimate the relative risk of injury among horses deemed to be at increased risk of injury on the basis of prerace physical inspection findings and to examine the association of injury during races with race-related characteristics. DESIGN: Cohort study. ANIMALS: 2,187 Thoroughbred horses that started 3,227 races in Kentucky. PROCEDURE: All race starts for which a horse was deemed to be at increased risk of injury on the basis of prerace physical inspection findings and a random sample of race starts for which horses were not deemed at increased risk of injury were included in the study. Findings of prerace physical inspection, race-related characteristics, and outcome of the race (race results and whether the horse incurred an injury) were recorded for each race start. Race starts in which a horse incurred an injury during a race were compared with race starts in which injuries were not incurred to identify factors associated with injury during races. RESULTS: Abnormality of the suspensory ligament of the forelimbs detected during prerace physical inspection, racetrack, class of race (claiming race < or = $25,000 vs other classes), and distance of race (< 7 furlongs vs other distances) were significantly associated with increased risk of injury. CONCLUSIONS AND CLINICAL RELEVANCE: Prerace physical inspection findings, particularly abnormalities of the suspensory ligament, may be used to identify horses at increased risk of injury during races. Rate of injury differed among racetracks, and horses in certain types of races (lower-priced claiming races and races of shorter distance) may be at increased risk of injury during races.     

Clinical findings, diagnosis, prevalence and predisposing factors for lameness localised to the middle carpal joint in young Standardbred racehorses

REASONS FOR PERFORMING STUDY: Lameness related to the middle carpal joint (MCJ) occurs in up to 30% of young Standardbred horses in race training and the incidence increase with radiographic severity of third carpal bone (C3) sclerosis on DPr-DDIO (skyline) view of the carpus. Factors predisposing horses to carpal injury have not been well investigated. OBJECTIVES: To determine the importance of MCJ lameness as a cause of wastage in young Standardbred racehorses, stage of training at which it occurs and predisposing factors, and to describe clinical findings and diagnosis. METHODS: Standardbred horses (n = 114) entering their first year of race training were examined at approximately 3-month intervals over 12-18 months. For 87 of the horses, a training diary was available and these horses were trained at 3 different stables, each using a different exercise regime. At each examination, forelimb conformation, MCJ effusion, MCJ lameness and radiographic findings were graded, and training history and reasons for lost training days recorded. Nuclear scintigraphy and exploratory arthroscopy were performed on a limited selection of horses. Results for horses that developed MCJ lameness during the study period were compared statistically with results for horses that did not. RESULTS: Carpal lameness occurred in 28% of horses and was present in 56% with forelimb lameness. In most cases lameness was mild, bilateral and with little or no MCJ effusion and was attributed to subchondral bone pain associated with radiographic evidence of C3 sclerosis. Carpal lameness was the most common reason for >1 month's rest during the study period. It occurred at any stage of training but, in most cases, some speed training had begun. Of the variables studied, poor forelimb conformation and more intense speed training were predisposing factors. CONCLUSIONS AND POTENTIAL RELEVANCE: The information gained should assist in making recommendations regarding training young Standardbreds to reduce the incidence of MCJ lameness. However, further investigations to determine the optimal training regime are warranted.     

Bite and kick injuries in horses: prevalence, risk factors and prevention

REASON FOR PERFORMING STUDY: Studies on the prevalence and predisposing factors of bite and kick injuries in horses have not been reported in a population-based data sample. OBJECTIVES: To investigate the prevalence of bite and kick injuries in horses and associated risk factors in a representative sample of horses in Switzerland. METHODS: A questionnaire on the incidence of disease and injury, which included the frequency of bite and kick injuries and their association with breed, housing, use and feeding regime, was sent to 2559 horse owners randomly selected throughout Switzerland. RESULTS: The data of 2912 horses with 897 disorders diagnosed by a veterinarian were analysed. There were 231 injuries, 50 (21.6%) caused by a bite or kick from another horse; this number corresponded to 5.6% of all diseases and injuries and concerned only 1.7% of all the horses evaluated. Warmblood, Thoroughbred and Arabian horses had a 4.3 times higher risk of bite or kick injuries than horses of other breeds. Eighteen per cent of injuries were associated with a change in housing management and occurred regardless of whether horses were kept in groups permanently or sporadically. CONCLUSIONS AND POTENTIAL RELEVANCE: A stable group hierarchy and a housing system that provides adequate space and is adapted to horse-specific behaviour are important factors in prevention and kick and bite injuries.     

Risk factors for the hazard of lameness in Danish Standardbred trotters

A follow-up study focusing on health problems interfering with optimal training of Danish Standardbred trotters was conducted with the participation of seven professional trainers. Our aim was to estimate the incidence of health problems that cause interruptions of optimal training, and to identify associations between the hazard of lameness and selected risk factors.The study population was dynamic and contained data of 265 Standardbred trotters monitored during 5 months in 1997 and 1998. The horses were >or=2 years old. Optimal training was defined as when the horse followed scheduled training including fast-speed trotting. Interruption of optimal training could only be caused by health problems and castration.A total of 123 new events of interruption of optimal training caused by health problems were reported. Lameness (injury located to joints and tendons) was the most-frequent cause of interruption of optimal training: 84 events in 69 horses (0.09 events per horse-month). Respiratory diseases (16 events) and muscular problems (seven events) were the second and third most-frequent causes of interrupted training.The effects of trainer, gender, age-group, time with a trainer, participation in races and current month on the hazard of lameness were estimated in a multivariable Cox proportional-hazard model. The effects of trainer, gender and age-group were modelled as time-independent. The effects of time with a trainer, participation in races and the current month were modelled as time-dependent variables.Trainer affected the hazard of lameness. Geldings had higher hazard than mares, as did 3-year olds (compared to >4-year olds). Compared to the period where horses had been trained by the same trainer for >3 months, horses in the period 1.5-2.5 months after they had entered the training regime had higher risk of lameness (hazard ratio: 3.2; 95% CI: 1.1-9.9). Participation in races increased the hazard of lameness significantly in the 5 days after a races.     

Descriptive epidemiology of fracture,tendon and suspensory ligament injuries in National Hunt racehorses in training

Reasons for performing study: While fractures and tendon injuries are known to be important diseases in National Hunt (NH) racehorses during racing, there are no accurate estimates of their incidence in NH training yards. Objectives: To estimate the incidence of fractures and tendon and suspensory ligament injuries (TLIs) in NH racehorses in training; to describe the injuries incurred and to compare injury incidence rates by horse age, trainer, gender and background (ex‐flat vs. ex‐store horses). Methods: Cohort data were collected from 14 UK NH training yards for 2 racing seasons. Daily exercise regimens and details of fractures and TLIs occurring in study horses were recorded. Results: Data were gathered from 1223 horses that spent 9466 months at risk of injury. The fracture incidence rate was 1.1/100 horse months and varied significantly by trainer (P<0.001) but not by gender, age or background. The pelvis and third metacarpal bone (MCIII) were the most common fracture sites, although this varied between racing and training. The TLI incidence rate was 1.9/100 horse months and varied significantly by trainer (P = 0.05) and age (P<0.001) but not by gender or background. However, exstore horses were significantly more likely to have a TLI on the racecourse than ex‐flat horses (P = 0.01). Superficial digital flexor injuries accounted for 89% of all TLIs, the remainder being suspensory ligament injuries. Conclusions and potential relevance: Fractures and TLIs are important causes of morbidity and mortality in NH racehorses in training in England. This study provides accurate estimates of their incidence in this population and provides a baseline against which to monitor the effect of future interventions.     

Evaluation of Surgical Removal of Fractured Distal Splint Bones in the Horse

Between January 1977 and June 1980, 38 Standardbred and 23 Thoroughbred horses had fractured distal splint bones removed surgically. Standardbred horses were treated significantly more frequently compared with the hospital population. The incidence of distal splint bone fractures in the front legs was significantly greater (p 0.05) than in the rear legs in both breeds. Associated suspensory desmitis was present in 81% of Standardbred and 67% of Thoroughbred horses at the time of surgery.
The most common radiographic sign was fracture with associated callus. It was not possible to correlate preoperative radiographic signs with presence of associated suspensory desmitis. One Thoroughbred horse developed a large mass of amorphous bone at the surgical site which required a second surgical procedure.
Follow-up information was available on 21 of 38 Standardbred and 17 of 23 Thoroughbred horses. There was no correlation found between preoperative radiographic signs or the location and number of distal splint bone fractures with postoperative results. Twenty-five percent of Standardbreds that had preoperative suspensory desmitis eventually reached at least their previous level of performance. None of the Thoroughbred racehorses with preoperative suspensory desmitis returned to their previous level of performance. Five of 17 Thoroughbred horses were pleasure horses, and all were reported "sound for intended use" following surgery; however, only four of five were used at their previous level of performance.
The significant feature in the prognosis of distal splint bone fractures in this series was the presence of associated suspensory desmitis. Postsurgical performance was limited by the recurrence of suspensory desmitis.     

Descriptive epidemiology of fractures occurring in British Thoroughbred racehorses in training

REASONS FOR PERFORMING STUDY: Musculoskeletal injury is the major cause of days lost from training and wastage in Thoroughbred racehorses. Little scientific information is available on the majority of injuries occurring in training. OBJECTIVES: To estimate the incidence of fractures in British racehorses in training and describe the occurrence of different fracture types and bones involved. METHODS: Thirteen UK racehorse trainers participated in a prospective study, providing data on horses in their care for 2 years. Details on horses, their daily exercise and fracture occurrence were recorded. RESULTS: A total of 1178 horses provided 12,893 months at risk. Nontraumatic fracture incidence was 1.15/100 horse months (95% CI = 0.98, 1.35) and 78% of fractures occurred during training. A wide variety of fracture types and bones were involved, although at least 57% were stress fractures. Pelvic and tibial stress injuries accounted for 28% of fractures diagnosed. CONCLUSIONS: It is important to study injuries in training as well as in racing. The number of stress fractures suggests that training regimes for young Thoroughbreds could often be improved to create a more robust skeleton, able to withstand injury. POTENTIAL RELEVANCE: Studying injuries in racehorses in training can provide a scientific basis for the design of safer training regimes.     

Comparison of grass haylage digestibility and metabolic plasma profile in Icelandic and Standardbred horses

The aim of the present study was to compare digestibility and metabolic response in Icelandic and Standardbred horses fed two grass haylages harvested at different stages of maturity. Six horses of each breed were used in a 24‐day change‐over design. A total collection of faeces was made on days 15–17 and 22–24. Blood samples were collected on day 24 of each period and analysed for total plasma protein (TPP), plasma urea, non‐esterified fatty acids, cortisol and insulin concentration. There were no differences in digestibility coefficients of crude protein, neutral detergent fibre or energy between breeds but organic matter digestibility was higher in the Standardbred horses. On both haylages, the Icelandic horses gained weight whereas the Standardbred horses lost weight. The Icelandic horses had higher TPP, plasma insulin and lower plasma urea concentrations. Our results indicate that the Icelandic horse may be more prone to maintain positive energy balance in relation to the Standardbred horse, but there were no indication of a better digestive capacity in the Icelandic horses.     

Gastric ulcers in standardbred racehorses: prevalence,lesion description,and risk factors

This study was performed to estimate the prevalence of gastric ulcers in Standardbred racehorses, to describe the lesion score and location, and to identify potential risk factors. Two hundred seventy-five (275) Standardbred horses from 5 training centers and 2 racetracks in Quebec, Canada, were studied. Historical data for the 2 months before examination were recorded for each horse, and the presence of gastric ulcers was determined by gastroscopy. A previously reported scoring system that used grades 0-3 for gastric lesions was used. Overall, 121 horses (44.0%; 95% CI, 38.1-50.1%) had gastric ulcers. The prevalence of gastric ulcers was significantly higher (P < .0001) in actively racing horses (63.3%; 95% CI, 54.7-71.2%) than in horses at rest. Multivariate analysis defined that horses in racing (OR = 9.29; 95% CI, 3.55-24.3) were significantly more likely to have gastric ulcers than horses at rest and that trotters (OR = 2.23; 95% CI, 1.28-3.86) were more likely to have gastric ulcers than pacers. The number of lesion sites (P < .0001) and poor body condition (P < .0001) were significantly associated with lesion scores. Gastric ulcers are highly prevalent in Standardbred racehorses. Furthermore, actively racing horses and trotters are more likely to have gastric ulcers. Also, poor body condition in Standardbred racehorses may be an indication that gastric ulcers are present and that lesion scores are high. The cause-and-effect relationship between poor body condition and the presence of gastric ulcers is unclear.     

A case-crossover study of intensive racing and training schedules and risk of catastrophic musculoskeletal injury and lay-up in California Thoroughbred racehorses

The objective of this study was to investigate the relationship between intensive racing and training schedules and risk of either catastrophic musculoskeletal injury (CMI) or lay-up from racing in California Thoroughbreds. Thoroughbred racehorses that sustained a CMI during racing or training and either were subsequently euthanized or died on a California racetrack during 1991 and 1992 were studied using a case-crossover study design. Each study subject (case) provided its own self-matched control information in the form of ‘typical’ exposure frequency, determined or estimated from historic information. Periods of rapid average daily accumulation of high-speed exercise distance were identified for each horse from official race and training histories with a sliding 60-day window. Those window frames containing an average daily rate of distance accumulation exceeding 75th percentile cutoff values were classified as exposed frames followed by 30 days of increased risk, or hazard periods. All remaining days (excluding periods of layoff from racing) were considered non-hazard time at risk. The relative risk (RR) of CMI within 30 days following a period of rapid accumulation of high-speed exercise distance (during a hazard period) was 4.2 (95% confidence interval [CI]= 3.0, 5.8). Of these 214 cases, 84 (39%) were injured during a hazard period whereas on average only 22% of total career time at risk was hazard time for these horses. A second analysis was performed for horses with at least 1 lay-up period from racing of ≥ 60 days. RR for a lay-up beginning during a hazard period was estimated for the last lay-up experienced by each horse. The RR for lay-up beginning during a hazard period was 4.8 (95% CI = 2.9, 8.1). Of these 98 cases, 32 (33%) of the lay-ups began during a hazard period whereas on average, only 22% of at-risk time up to last lay-up was hazard time for these horses.     

Catastrophic biaxial proximal sesamoid bone fractures in UK Thoroughbred races (1999–2004): Horse characteristics and racing history

Reason for performing study: Catastrophic biaxial proximal sesamoid bone fractures (PSBF) have not yet been described in detail in the UK racing population. Objectives: To determine the incidence and relative risk (RR) of PSBF in different types of racing in the UK; and to describe horse‐level characteristics and racing histories of horses sustaining these injuries. Methods: Distal limbs were collected from all racehorses suffering catastrophic fractures during racing at all 59 racecourses in the UK, in a prospective study from February 1999 to December 2004. Post mortem investigation identified the anatomical location and type of fracture. Horse, racing history, race and racecourse details were obtained. Characteristics of the horses that sustained PSBF were described. The incidence and RR of PSBF in the different types of racing in the UK were calculated. Results: Thirty‐one horses suffered PSBF during the study period. The incidence of PSBF in all types of race was 0.63 per 10,000 starts (31/494,744). The incidence was highest in flat races on all weather surfaces (1.63 per 10,000 starts: 12/73,467; RR = 4.4 when compared to turf flat racing). Affected horses had an average age of 5.6 years and had started a mean of 28 races at the time of fracture. Conclusion and potential relevance: There is a strong association between type of racing surface and PSBF. Horses competing in flat races on all weather surfaces have an increased risk of PSBF. These fractures appear to happen in experienced horses with several starts, with few fractures occurring within the first season of racing. Further research should focus on identification of underlying pathology of these fractures. Epidemiological studies aimed at the identification of risk factors for PSBF in the UK racing population would require a large number of cases acquired over many years given the relatively low incidence of PSBF.     

Risk factors for equine acute abdominal disease (colic): Results from a multi-center case-control study

Many causal hypotheses for acute equine abdominal disease (colic) have been proposed. However, few epidemiologic studies have been undertaken to identify risk factors for the syndrome. Risk factors for equine colic were identified using a hospital-based, multi-center, case-control study. Horses admitted with abdominal pain to Cornell, Guelph, Ohio State, Pennsylvania or Tufts university veterinary hospitals between March and December 1991 were selected. Control horses were randomly selected from a list of all other non-colic admissions. The person(s) responsible for the day-to-day care of the horse completed a telephone questionnaire. Risk factors were identified using multivariable logistic regression analysis.

A total of 406 colic and 406 control horses were used in the final analysis. Age, breed, outdoor access (pasture or drylot), outdoor water supply, use of a daily worming product, amount of concentrates and whole-grain corn consumed, type of person responsible for the day-to-day care of the horse and previous colic history were all significantly associated with colic risk. Arabian horses were more than twice as likely to be colic cases (OR = 2.0, 95% CI = 1.0–3.9), whereas Standardbred horses were nearly half as likely (OR = 0.6, 95% CI = 0.4–1.0) to be colic cases compared with the comparison Thoroughbred group. Horses that had access to outdoor enclosures without a continuous supply of water were more than twice as likely (OR = 2.2, 95% CI = 1.2–4.3) to be colic cases compared with horses that had an adequate supply of water on outside enclosures. The use of a daily worming product for at least 60 days during the 12-month period prior to presentation was associated with a significantly lower colic risk (OR = 0.11, 95% CI = 0.02–0.55). Colic risk increased with greater consumption of whole-grain corn; however, when all non-roughage concentrate feeds were combined, colic risk decreased with increased intake of concentrates. Significant interactions were identified between age and drylot use and between the type of care-person responsible for the day-to-day care of the horse (owner or non-owner) and previous colic history.

The findings of this study illustrate the complex multi-factorial nature of equine colic and point towards the importance of the overall quality of stable management and care, as well as the type of outdoor enclosure (pasture or drylot), water access, carbohydrate intake, parasite control and intrinsic (breed-related) factors.     

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

Reasons for performing study: Superficial digital flexor (SDF) tendinopathy is a common injury in Thoroughbred horses racing over hurdles. Identification of risk factors may allow the introduction of measures to minimise the incidence of this injury. Objective: To identify risk factors for SDF tendinopathy in Thoroughbred horses in hurdle races in the UK. Methods: Potential risk factors for SDF tendinopathy were studied between 1 January 2001 and 31 December 2009 using a retrospective cohort study design with 1031 case starts and 168,637 control starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. Results: In the final multivariable model, 20 statistically significant risk factors were identified. Variables found to be associated with increased odds of SDF tendinopathy included: firmer going; increased horse age at first race; having had a previous SDFT injury; and racing in the summer compared to other seasons. Variables found to be associated with decreased odds included: being trained by a more successful trainer; and having raced more frequently in the preceding 9–12 months. Conclusions: This study identified multiple risk factors associated with SDF tendinopathy, some of which are difficult to explain with the current data source. Factors resulting in increased cumulative horse and tendon fatigue (increased years in racing; carrying increased weight; and racing over longer distances), firm ground, and the presence of previous tendon injury should be considered when attempting to reduce the likelihood of sustaining SDF tendinopathy. Potential relevance: The results will facilitate the development of strategies to improve the overall safety of horses in hurdle racing in the UK.     

Musculoskeletal injuries in Thoroughbred racehorses: A study of three large training yards in Newmarket, UK (2005–2007)

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.     

Evaluation of horseshoe characteristics and high-speed exercise history as possible risk factors for catastrophic musculoskeletal injury in thoroughbred racehorses

OBJECTIVE: To evaluate horseshoe characteristics and high-speed exercise history as risk factors for catastrophic musculoskeletal injury in Thoroughbred racehorses. ANIMALS: 377 horses (37,529 race starts). PROCEDURES: Shoe characteristics included material, toe grab height, heel traction device, pads, and rim shoes. Racing variables were obtained from a computerized database. Forty-three horses that had a musculoskeletal injury and then failed to race or train for 6 months (cases) and 334 noninjured horses from the same race in which a horse was injured (controls) were compared regarding risk factors. RESULTS: Overall, 98% of race starts were associated with aluminum shoes, 85% with toe grabs, 32% with pads, and 12% with rims on forelimb horseshoes. Among 43 horses with musculoskeletal injury, sex (geldings), an extended interval since last race, and reduced exercise during the 30 or 60 days preceding injury were risk factors for catastrophic injury. Odds of injury in racehorses with toe grabs on front shoes were 1.5 times the odds of injury in horses without toe grabs, but this association was not significant (95% confidence interval, 0.5 to 4.1). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that horses that return to racing after an extended period of reduced exercise are at high risk of catastrophic musculoskeletal injury. Results regarding the use of toe grabs as a possible risk factor for catastrophic injury were inconclusive because the probability of declaring (in error) that use of toe grabs was associated with an increased risk of musculoskeletal injury (eg, odds ratio > 1.0) was 38%.     

Prognostic Indicators after Musculoskeletal Injuries in Standardbred Racehorses in Italy

The objective of this study was to report recovery time, retirement rate, racing performance, and presence of compensation pattern after musculoskeletal injuries (MSIs) in Standardbred racehorses (STBRs). This is a retrospective single open-cohort study, enrolling 356 STBRs in training in a single racetrack. Musculoskeletal injury was defined as any training-related injury after which the horse did not train for at least 15 days. The first and second MSIs encountered during the horse’s racing career were considered. Medical records, training logbooks, and racing data were reviewed to determine recovery time, retirement rate, racing performance, and compensation pattern after MSIs. Kaplan–Meier estimators considered the return to activity as primary endpoint. The hazard ratio (HR) for return to activity was determined using Cox proportional hazard models, after classifying horses based on the injury type. A total of 543 MSIs were considered. The 33.6% (95% confidence limits [CL]: 29.5, 37.8) of STBRs suffering from MSI had to be retired as consequence of that. The median recovery time after MSI was 119 days (95% CL: 47, 179). Horses with traumatic osteoarthritis had a greater likelihood of returning to athletic activity compared with horses with stress fractures (HR = 4.8, 95% CL: 3.5, 6.7) and tendon/ligament strains (HR = 4.1, 95% CL: 3.1, 5.4). Increased racing speed was recorded after injuries. The second MSI was more often localized to the contralateral limb compared with the first injury (odds ratio (OR) 6.35, 95% CL: 4.29, 8.51), diagonal (OR 4.59, 95% CL: 3.05, 6.27) and to the same limb (OR 3.17, 95% CL: 2.03, 4.47) than to the ipsilateral limb.