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.