Frequency of diseases and injuries in the Swiss horse population

Through a written questionnaire, which was sent to a representatively distributed and randomly selected sample of Swiss horse owners, data of 2912 horses and ponies were acquired to extrapolate prevalence data of health disorders. General questions about the horse and associated factors of housing and use, as well as questions about the current health status and the occurrence of diseases and injuries had been asked. 718 horses (24.7% of the sample) had been examined by a veterinarian within the 12 months prior to the survey. Orthopaedic and traumatic disorders (41.5%) had the largest proportion, followed by gastrointestinal--(27.1%) and respiratory (14.0%) diseases. Half of the lameness cases occurred as a direct consequence of a injury. The injuries were associated with pasture/paddock (38.1%), kicking and biting (21.6%), boxstall (7.8%), terrain and hacking (13.4%), training (3.5%), competition (3.5%), transportation (3.0%) or other circumstances (9.1%). A change in feeding management up to 4 weeks before development of a colic episode occurred in 26.5% of all colic cases. In 13.8% of all respiratory cases the same disease was diagnosed in other horses in the same barn. 8.1% of all cases had to be treated surgically, 6.7% required hospitalization for several days. Information about diagnostic or therapeutic procedures was related to specific disease categories. In 25.6% of all cases diagnosed by a veterinarian alternative therapeutic methods were used either in addition to traditional medicine or exclusively.     

Risk factors associated with behavioural disorders of crib-biting,weaving and box-walking in Swiss horses

REASONS FOR PERFORMING STUDY: Studies on the prevalence of behavioural disorders in horses and on associated risk factors have revealed inconsistent results. There are many studies on the neuropharmacological, surgical or mechanical therapy of stereotypies, but little is known about their causation. OBJECTIVES: To explore risk factors associated with the occurrence of behavioural disorders in horses. METHODS: A sample of horse owners, selected randomly and representative for Switzerland, was contacted in a postal survey. Answers were provided for 622 stables (response rate 35.2%). Individual data of 2,341 horses were examined with path analysis (multivariable linear and logistic regression), and adjustment made for possible confounding effects due to age and breed. RESULTS: Out of 60 possible risk factors, 11 were associated with the outcome at the univariable level (null-hypothesis path model) and 3 factors remained after the backward logistic regression procedure. Mature Warmbloods and Thoroughbreds, assessed by the owners to be reactive, fed 4 times a day and without daily pasture, had increased odds of displaying crib-biting, weaving and box-walking. Furthermore, indirect associations of 5 factors with the outcome were identified. CONCLUSIONS: The final logistic regression model of risk factors leads to the hypotheses that causal prevention of stereotypic behaviours should be based upon housing and management conditions which allow tactile contact with other horses (e.g. mutual grooming), daily free movement (paddock or pasture), as well as the provision of high amounts of roughage but of little or no concentrates. POTENTIAL CLINICAL RELEVANCE: It is one of the aims of population medicine to prevent the development of behavioural disorders. Further research is needed to test the concluding hypotheses in experimental studies or to verify them in the context of similar observational studies.     

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.     

Kick injuries of veterinarians during examination and treatment of horses: a retrospective study in Switzerland

The risk of injury to veterinarians treating horses is high, particularly when performing painful procedures. The present retrospective study investigated this risk, including the frequency and severity of kick injuries, by submitting questionnaires to 700 veterinary practitioners in Switzerland. Evaluation of 216 completed questionnaires revealed that the frequency of kick injuries was affected by the professional experience of the veterinarian, veterinarians being an owner of a horse, the season, the type of procedure, the percentage of equine patients in the practice population, the treatment location (stall, pasture) and chemical restraint of the patient. Severe injuries incurred by veterinarians in recent years were few in number and the result of a number of unfortunate circumstances, which included hurried procedures due to time restraints and unforeseen events that frightened the patient. The risk factors derived from the full statistical model are the percentage of equine patients in the practice population, the treatment location, the type of procedure and chemical restraint of the patient. Using this information, it should be feasible to reduce the risk of injuries. Sedation of horses undergoing painful procedures, choosing a safe treatment location and caution on the part of the veterinarian are advised to reduce the number of injuries.     

Housing and use of horses in Switzerland: a representative analysis of the status quo

Out of a representative sample of 1861 Swiss horse yards, 622 horse keepers (35.2%) with 2536 horses, ponies and donkeys sent back a questionnaire about general farm characteristics, their horse-specific training, horse stock, housing conditions, intraspecific social contacts, feeding, ability to move freely, use of the horses and management. 83.5% of horses were kept individually (thereof 18.3% tethered, 32.3% in a loose box indoors, 28.4% in a loose box outdoors, and 4.5% in a loose box with permanent access to a paddock or an individual pasture), and 16.5% lived in group housing systems. 36% of the horses had daily access to a pasture, 62.8% depending on the weather, and 1.2% never at all. Individually housed horses pastured significantly less than horses kept in groups. The mean use per week was 4.5 hours, depending on breed, type of use and housing system. Only 50% of the horse keepers were trained with respect to horses or farm animals (e.g. professional training graduation, license, military service, veterinarian, farmer). In Switzerland, horses are still housed and fed in a traditional way, despite considerable recent changes in the amount and type of use (65.1% leisure horses, 34.9% sport and working horses); this may result in health and behavioural problems. Therefore, information and education of horsewomen and horsemen should be emphasized in the future. For the transfer of knowledge, veterinarians are of high importance.     

Crib‐biting in US horses: Breed predispositions and owner perceptions of aetiology

Reasons for performing study: Crib‐biting is an equine stereotypy that may result in diseases such as colic. Certain breeds and management factors have been associated. Objectives: To determine: breed prevalence of crib‐biting in US horses; the likelihood that one horse learns to crib‐bite from another; and owner perceptions of causal factors. Methods: An initial postal survey queried the number and breed of crib‐biting horses and if a horse began after being exposed to a horse with this habit. In a follow‐up survey, a volunteer subset of owners was asked the number of affected and nonaffected horses of each breed and the extent of conspecific contact. The likelihood of crib‐biting given breed and extent of contact was quantified using odds ratio (OR) and significance of the association was assessed using the Chi‐squared test. Results: Overall prevalence was 4.4%. Thoroughbreds were the breed most affected (13.3%). Approximately half of owners believed environmental factors predominantly cause the condition (54.4%) and crib‐biting is learned by observation (48.8%). However, only 1.0% of horses became affected after being exposed to a crib‐biter. The majority (86%) of horses was turned out in the same pasture with other horses and extent of contact with conspecifics was not statistically related to risk. Conclusion: This is the first study to report breed prevalence for crib‐biting in US horses. Thoroughbreds were the breed more likely to be affected. More owners believed either environmental conditions were a predominant cause or a combination of genetic and environmental factors contributes to the behaviour. Only a small number of horses reportedly began to crib‐bite after being exposed to an affected individual, but approximately half of owners considered it to be a learned behaviour; most owners did not isolate affected horses. Potential relevance: Genetic predisposition, not just intensive management conditions and surroundings, may be a factor in the high crib‐biting prevalence in some breeds, and warrants further investigation. Little evidence exists to suggest horses learn the behaviour from other horses, and isolation may cause unnecessary stress.     

Risk factors and prevalence of injuries in horses during various types of steeplechase races

OBJECTIVE: To identify the types of injuries sustained by horses that competed in steeplechase races and determine the prevalence of and risk factors for those injuries. DESIGN: Prospective study. ANIMALS: 2,680 horses that competed in various types of steeplechase races from 1996 through 2000. PROCEDURE: Data regarding races; environment; equipment problems; the number of horses that entered, started, and finished races; the number of riders that fell; and the number of horses that were slowed or stopped by the rider, ran off the course, fell, and sustained injuries or physical abnormalities during races were collected on a standard form by the official veterinarian who attended each meet. Data from all meets were not recorded; however, in recorded meets, data from every race were reported. RESULTS: Data for 197 hurdle, 65 timber, 76 flat, and 8 mixed races were recorded. Nine (3.4/1,000 horses that started in races) horses died or were euthanatized, and 7 of those were associated with catastrophic musculoskeletal injury. Seven fractures were recorded. Four fractures involved forelimbs, 1 involved a hind limb, and 2 involved the cervical portion of the vertebral column. All horses with fractures were euthanatized. Deep or hard course conditions were associated with an increased risk of breakdown injuries. CONCLUSIONS AND CLINICAL RELEVANCE: Successful development and implementation of strategies to prevent injuries and death in horses in steeplechase races depend on a clear understanding of the types and prevalence of injuries involved and risk factors associated with those injuries.     

Risk factors associated with hindlimb lameness and degenerative joint disease in the distal tarsus of Icelandic horses

The aim of this study was to evaluate potential risk factors associated with hindlimb lameness and radiographic signs of degenerative joint disease (DJD) in the distal tarsus in Icelandic horses. The material consisted of riding horses (n = 420) age 6-12 years sired by 17 selected sires representing all major breeding lines, and of riding horses (n = 194) in the same age range sired by other sires. The examination protocol included the following: interview with owners/trainers, assessment of conformation, motion evaluation and radiographic examination. At the interview, data related to factors outside the horse (environmental variables) and data associated directly with the horse (intrinsic variables) were obtained. Data analysis was performed in 2 steps: screening using bivariate analysis, followed by testing with a multivariate logistic regression model. In the multivariate analysis, the factors of sire, age when broken to saddle and stud show participation were strongly associated with the prevalence of lameness. Height at the croup and ability to perform different gaits were also associated with the prevalence of lameness, but to a lesser degree. The risk factors of age, tarsal angle and birthplace were significantly associated with radiographic signs of DJD in the distal tarsus. Neither the variation in applied training intensity, the use of a professional or amateur trainer nor the temperament or front limb action of the individual horse was significantly associated with the prevalence of hindlimb lameness and/or radiographic signs of DJD in the distal tarsus in the Icelandic horse.     

Fecal shedding of Salmonella spp by horses in the United States during 1998 and 1999 and detection of Salmonella spp in grain and concentrate sources on equine operations

OBJECTIVE: To estimate prevalence of fecal shedding of Salmonella spp among horses in the US horse population and prevalence of Salmonella spp in grain or other concentrate used as horse feed on equine operations in the United States. DESIGN: Cross-sectional survey. SAMPLE POPULATION: Horses on 972 operations in 28 states. PROCEDURE: Fecal samples were collected from horses resident at each operation. Only a single sample was collected from any individual horse; number of horses from which samples were collected on each operation was determined on the basis of number of horses on the operation. A single sample of grain or concentrate was also collected from each operation. All samples were tested for Salmonella spp by means of bacterial culture. RESULTS: Overall, 0.8% (SE, 0.5) of resident horses shed Salmonella spp in their feces. The overall prevalence of operations positive for fecal shedding of Salmonella spp (i.e., operations with > or = 1 horse shedding Salmonella spp in its feces) was 1.8% (SE, 0.7). Prevalence of grain or other concentrate samples positive for Salmonella spp was 0.4%. Serotypes of Salmonella spp that were identified in grain or other concentrate were not those typically associated with clinical disease in horses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the national prevalence of fecal shedding of Salmonella spp by horses in the United States was 0.8%, and that prevalence of Salmonella spp in grain or other concentrate used for horse feed was 0.4%.     

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.     

A survey of horse owners in Great Britain regarding horses in their care. Part 2: Risk factors for recurrent airway obstruction

REASONS FOR PERFORMING STUDY: Recurrent airway obstruction (RAO) is a commonly encountered respiratory condition of horses. Despite this, the epidemiology of this predominately manageable and reversible disease in Great Britain has been largely ignored. OBJECTIVES: To estimate the prevalence of RAO in the general horse population of Great Britain and to investigate possible risk factors for RAO associated with management or early life. METHODS: Horse owners were surveyed using a self-administered postal questionnaire that contained a risk-screening questionnaire (RSQ) designed to identify horses with RAO. These owners were randomly selected, following geographical stratification, using 2-stage cluster sampling of veterinary practices and their clients. Multilevel, multivariable logistic regression models were used to investigate risk factors for RAO in the selected horse population. RESULTS: The estimated true prevalence of RAO in the selected horse population was 14.0% (95%CI 10.7-17.4%). Risk factors for RAO identified in a general horse management logistic regression model included increasing age and exposure to an urbanised environment. Recurrent airway obstruction has long been associated with mature horses while the association with an urbanised environment could be related to different management practices in these areas or possibly air pollution could be involved. The second model associated exposure to hay and respiratory infection in early life with a horse having RAO in later life. Challenges to the respiratory system in early life may be involved in the development of this disease. CONCLUSIONS AND POTENTIAL RELEVANCE: Recurrent airway obstruction is a significant health problem in the horse population of Great Britain. This form of epidemiological investigation highlights potential risk factors for the disease.     

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.     

Dietary and other management factors associated with colic in horses.

OBJECTIVE: To determine whether dietary and other management factors were associated with development of colic in horses. DESIGN: Prospective matched case-control study. POPULATION: 2,060 horses examined by veterinarians in private practice in Texas for colic and noncolic emergencies. PROCEDURE: Each month for 12 months, participating veterinarians were sent forms to collect information on 1 horse with colic and 1 horse that received emergency treatment for a condition other than colic, information collected included signalment, farm management and characteristics, diet, medical and preventive medical factors, transport, and activity or use. Case and control horses were compared by means of conditional logistic regression to identify factors associated with colic. RESULTS: Recent change in diet, recent change in type of hay, history of previous episode of colic, history of abdominal surgery for colic, recent change in weather conditions, recent change in housing, Arabian breed, administration of an anthelmintic during the 7-day period prior to examination, failure to receive regular deworming, age > 10 years, and regular exercise (vs pastured at all times) were associated with increased risk of colic. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that changes in diet (particularly in type of hay fed) contribute to increased risk of colic. A regular program for administration of anthelmintics may reduce the overall frequency at which colic develops, but recent administration of anthelmintics may predispose some horses to colic. Arabian horses may have an increased risk of colic, and horses at pasture may have a decreased risk of colic.     

Post anaesthetic colic in horses: a preventable complication?

REASONS FOR PERFORMING STUDY: There is little information on the prevalence of, and risk factors associated with, post anaesthetic colic (PAC) in horses undergoing nonabdominal operations. OBJECTIVES: To undertake the first prospective study of prevalence of PAC and identify risk factors in its development in nonabdominal procedures. METHODS: A multicentre prospective case-control study was conducted, on every horse undergoing anaesthesia for a nonabdominal procedure between April 2004 and June 2005. Colic cases were defined as any horse with recognised signs of abdominal pain within 72 h of general anaesthesia that could not be attributed to any concurrent disease. Five control horses per case were selected randomly from the study population at all hospitals. Multivariable logistic regression analysis was used to examine the relationship between predictor variables and the risk of developing PAC. RESULTS: The estimated mean prevalence of PAC in the study population was 5.2% (95% CI, 2.8, 8.0). However, the prevalence of colic varied between each centre. The most commonly diagnosed cause of colic was impaction. Multivariable analyses showed that the centre involved and the type of surgery performed were associated with an increased risk of PAC. Preoperative food deprivation and the use of opioid drugs were confounding factors. CONCLUSIONS: Prevalence of PAC varied significantly between the 4 hospitals studied; there may be hospital-related covariates that account for this. The type of surgery performed influenced the risk of PAC. POTENTIAL RELEVANCE: Identifying the risk factors for PAC is a prerequisite for its prevention. This study indicates horses at increased risk of PAC that might benefit from a more critical evaluation of post anaesthetic gastrointestinal function and/or the provision of preventative measures. Further investigation is required to explain the variation in prevalence of PAC between centres.     

Prevalence of behavioral disorders in the Swiss horse population

In the Swiss horse population, the prevalence of conspicuous behaviours (behavioural disorders and stable vices) was recorded with a written questionnaire in a representative survey among 1861 horse yards, and the occurrence of the stereotypic behavioural disorders crib-biting, weaving and boxwalking was analysed with emphasis on their association with horse specific (breed, age, sex) and environmental factors (e.g. housing system, nutrition, management and utilisation). 622 horse yards with a total number of 2536 horses answered to the questionnaire, and conspicuous behaviours were described for 418 horses (16.5%). Thereof, the most common stereotypic behavioural disorders with a potential negative impact on animal welfare, crib-biting, weaving, and/or boxwalking were named for 89 horses (3.5%). Stable vices (e.g. shying, bucking, aggressivity against humans) were noted for 47 horses (1.9%). For 281 horses (11.1%) conspicuous behaviours such as pawing, lip-liking, head shacking, kicking stall were given; these can be categorised as behavioural disorders or as stable vices depending on their intensity and causation. Data analysis data revealed a number of statistically significant associations between genetic factors (breed), housing, management practices, utilisation and the three stereotypies. The strongest influence on the degree of behavioural disorders had the breed as well as the extent of direct social contact with other horses, free movement on pasture, feeding pattern and regular utilisation.     

A retrospective case-control study of horse falls in the sport of horse trials and three-day eventing

REASONS FOR PERFORMING STUDY: Serious injuries to horses and riders in horse trials (HT) and three-day events (3DE) are usually associated with falls of horses, which invariably involve falls of the riders. Many potential causes for these falls have been discussed. OBJECTIVES: The aim of this case-control study was to investigate the risk factors for horse falls on the cross-country phase of horse trials and three-day events. METHODS: Using retrospective data, significant risk factors identified with unvariable analysis (P value <0.2) were entered into a multivariable logistic regression model. Significant risk factors (P value <0.05) were included in the final model. RESULTS: It was revealed that a number of course, obstacle and rider variables were significantly and independently associated with the risk of falling. Falling was associated with obstacles sited downhill (Odds ratio [OR] 8.41) and with obstacles with ditches in front (OR = 5.77). CONCLUSIONS: The relationship between course variables and the risk of falling was characterised and showed a significantly increased risk with increasing numbers of jumps on the course and for jumping efforts later in the course. In contrast, after allowing for the total number of obstacles on the course, an increase in the total number of jumping efforts appeared to have a protective effect. A later cross-country start time was associated with a decreased risk of a horse fall. Amateur event riders were approximately 20 times more likely to fall than professional riders. POTENTIAL CLINICAL RELEVANCE: This study has identified a number of risk factors associated with horse falls and highlights areas that can be altered to improve safety in cross-country competitions.     

Prevalence of severe welfare problems in horses that arrive at slaughter plants.

OBJECTIVE: To assess the prevalence of severe welfare problems in horses that arrive at slaughter plants and to identify horses that were unfit for travel. DESIGN: Prevalence survey. ANIMALS: 1,008 horses. PROCEDURE: Horses arriving at 2 slaughter plants were observed. The following were rated severe welfare problems in horses: body condition scores of 1 or 2 (emaciated) of 9; recumbency (down) or the inability to walk; fractured limbs or other foot or limb problems that extremely impaired mobility; severe wounds, such as deep cuts, extensive lacerations, abrasions on the head or back, eye injuries, neglected purulent lesions, and numerous bite and kick marks over extensive areas of the body; and dead on arrival. Bruises on carcasses were tabulated to further assess injuries. Horses that had been loaded with a fractured limb, arrived nonambulatory, had severe lameness that interfered with mobility, were weak and emaciated, or were dead on arrival or died shortly after arrival were considered unfit for travel. RESULTS: Ninety-two percent (930/1,008) of the horses arrived in good condition, and 7.7% (78) had a condition that was rated a serious welfare problem. Thirty horses (3%) had a body condition score of 1 or 2, 12 (1.0%) had foot and limb problems (other than fractures), 4 (0.4%) had fractured limbs, 18 (2.0%) had deep cuts, lacerations, or injuries from bites, 8 (0.8%) were nonambulatory or dead on arrival, 2 (0.2%) had deformities, 3 (0.3%) had extensive purulent lesions, and 1 (0.1%) had a behavior problem. Characteristic patterns of 51% of carcass bruises indicated that they were caused by bites or kicks. Fighting was the major cause of injuries that occurred during transport and marketing. Fifteen (1.5%) horses were unfit for travel. Abuse or neglect by owners was the cause of 77% of the severe welfare problems observed. CLINICAL IMPLICATIONS: To decrease the number of injuries that result from fighting when transporting horses to slaughter plants, aggressive mares and geldings that continually attack other horses must be segregated.     

Musculoskeletal injuries in Standardbred racehorses on Prince Edward Island

A study of musculoskeletal injuries in Standardbred racehorses on Prince Edward Island was conducted to determine the incidence and risk factors for injury. Monthly information was collected from 10 trainers and 153 Standardbred horses over a 12-month period. Seventeen new injuries were identified in pacers, representing a horse level incidence risk of 23% and an incidence rate of injury of 2.19 per horse-month at risk. Forty-one percent of the injuries occurred during a race, 53% during training and 6% during jogging. Fourteen horses had experienced a previous injury and 3 of these horses experienced a new injury during the study period. Potential risk factors for injury were the speed at which the horse was trained, previous injury, and the conformational fault of offset knees.