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

Abstract

Summary 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.

Epidemiology of musculoskeletal injuries in a population of harness Standardbred racehorses in training

“…Supporting our findings, a study on middle carpal joint lameness in STBR showed that a higher incidence of third carpal bone pathology was not related to more intense exercise programs [8]. In contrast, epidemiological studies in young TBR demonstrated that different trainers were correlated with different MSI IRs [5,6].…”

“…Musculoskeletal injuries (MSI) are the primary cause of reduced training days and racehorse wastage in Standardbred racehorses (STBR) as well as in Thoroughbred racehorses (TBR) [1-6]. But, only a few research studies have attentively focused on STBR specific problems [7-10], such as middle carpal joint injuries [8] and proximal sesamoid bone fractures [9]. Large-scale studies on exercise-related MSI in this population are missing, compared to TBR, probably because in STBR catastrophic events are rare during competitions, thus not raising welfare concerns on racecourse safety.…”

“…In STBR training, the driver has been reported to be a risk factor for selected MSI in young animals [8]. STBR are rarely exposed to different environments because similar surfaces are commonly found in all racecourses and race distances are similar all over the world.…”

“…However, a number of specific risk factors need to be considered, like racetrack banking at the racecourse curves [7]. Methods employed in STBR training are all conceptually similar [8,10], although the volume and the intensity of training for young animals are variable and they could be considered risk factors for MSI. Generally STBR perform more frequently than TBR during their athletic careers.…”

Survey of trainers on the use of swimming exercise for Standardbred racehorses in Australia

“…Limited reports indicate that the risk is greatest with training programmes that are most intense in terms of weekly duration and weekly duration of exercise performed at maximal effort. 29,30 A training program with a 30% reduction in the highintensity distance covered during the first few years of training in Swedish Standardbreds was equally as effective in achieving performance goals and was associated with fewer lost training days. 31,32 Variation in training (cross-training) reduced the days-lost to training and competition from orthopaedic injury in elite showjumpers, 33 yet benefits of variation in activity have not been studied in Standardbreds.…”