A study of Italian standardbred trotters in training found they had lower rates of stress fracture than thoroughbreds, but higher rates of tendon and suspensory ligament injuries.
The researchers also found a strong link between racing intensity and injury rates.
The study, reported in the journal, BMC Veterinary Research, was carried out by Italian and Canadian researchers. It involved the monitoring of 356 trotters from 10 different stables. They contributed 8961 months at risk of musculoskeletal injuries.
In all, 429 injuries were reported and classified into 16 categories.
The overall exercise-related injury rate was 4.79 per 100 horse months.
The researchers, led by Andrea Bertuglia, from the Department of Veterinary Science at the Universita di Torino, found that injury rates did not differ significantly between genders and classes of age.
“Racing speed and racing intensity, as well as recent medical history, seemed to be significant risk factors, while being shod or unshod during racing was not.” Bertuglia and her colleagues reported.
“On the other hand, when pooling several risk factors in a multivariable approach, only racing intensity turned out to be significant, since racing speed and the racing intensity were partially confounded, being strongly correlated to one another.
“Incidence rates of stress fracture are lower in standardbreds compared to thoroughbreds, whereas the opposite is true for tendon and suspensory ligament injuries,” they found.
The researchers noted that there was a lack of studies concerning musculoskeletal injuries in harness standardbred racehorses. Most studies involved thoroughbreds, whose biomechanics and racing speed differed from standardbreds, making comparisons difficult, they said.
The study analyzed data in respect of 356 trotters at Italy’s Turin-Vinovo racecourse from January 1, 2008, to December 31, 2011, across 10 stables.
The incidence rates of musculoskeletal injuries causing horses’ withdrawal from training for 15 days or longer were investigated for the purposes of the study.
According to a retrospective study conducted in British flat racing, the most represented categories of injuries in thoroughbreds were pelvic and tibial stress fractures, followed by lateral condylar fractures of the third metacarpal and metatarsal bone.
While stress fractures and superficial digital flexor tendonitis (SDFT) were the commonest exercise-related lesions in thoroughbreds, suspensory ligament injury was the most common injury observed in the Italian study, followed by superficial digital flexor tendonitis.
“Damage to these structures accounted for 38.3 percent of the overall musculoskeletal injuries in our study,” the researchers reported.
“Tibial stress fractures are uncommon injuries in standardbreds, while lateral condylar fractures and biaxial proximal sesamoid bone fractures were not observed.
“Other than racecourse designs [and] racetrack surfaces, maximum racing speed and gait differences are likely to account for such differences between the two breeds.”
They observed: “The biomechanics of the ‘flying trot’ and the slower speed compared to high-speed gallop seems to reduce the likelihood of bone failure accidents.”
In all, 92.9 percent of horses in the study sustained at least one musculoskeletal injury requiring at least a 15-day layoff during their observation time.
Andrea Bertuglia, Michela Bullone, Federica Rossotto and Mauro Gasparini
Epidemiology of musculoskeletal injuries in a population of harness Standardbred racehorses in training.
BMC Veterinary Research 2014, 10:11 doi:10.1186/1746-6148-10-11
The study can be read here.