Relationship Between Historical Lameness, Medication Usage, Surgery, and Exercise With Catastrophic Musculoskeletal Injury in Racehorses

Abstract

Background: The rate of catastrophic musculoskeletal injuries (CMI) in racehorses is high in the United States compared to other countries. Few modifiable risk factors related to lameness, medication, and surgery history have been identified.Objective: To detect management factors that increase risk of CMI by comparing medical histories between horses that sustained, and horses that did not sustain, a CMI.Study design: Case-control.Methods: Racehorse necropsy data (May 2012-June 2013) were obtained through the California Horse Racing Board Postmortem Program. Attending veterinarians of Thoroughbreds (TB) and Quarter Horses (QH) that experienced CMI, and of three matched control horses, were invited to complete an online veterinary medical history survey. We investigated associations between CMI and lameness, medication, surgery, and exercise history using multivariable logistic regression.Results: There were 146 TB (45 cases, 101 controls) and 17 QH (11 cases, 6 controls) surveys completed. TB cases were more likely to show signs of lameness within the 3 months prior to death compared to controls. A high proportion of both cases (64.3%) and controls (76.8%) were administered medications, but unraced TB case horses were more likely to have been administered systemic medications compared to those that previously raced. TB cases were more likely to have raced with greater intensity during their career, but had eased off in the month preceding CMI. For QHs, there was insufficient power to detect significant differences between cases and controls that showed signs of lameness, or that were administered medications. Surgery history was not associated with CMI.Main limitation: Insufficient power to detect small effect sizes.Conclusions: The study provides information that can be used to aid in identification of horses at high risk for catastrophic injury, and management factors that can be modified to reduce the risk for all horses.

Training Young Horses: The Science behind the Benefits

“…Greater strength during maturity compared to non-exercised animals suggests that exercise while growing can provide lifelong benefits. Hitchens and colleagues [ 30 ] determined that Thoroughbred horses, which sustained a catastrophic musculoskeletal injury while racing or training, had eased off racing in the one to two months prior to the injury. The authors hypothesized that the lack of exercise could have been a result of the horse being unable to complete high-speed exercise due to an injury, or that, conversely, the lack of high-speed exercise led to decreased bone density, meaning the horse was racing with weaker, more porous bone.…”

Science‐in‐brief: Risk assessment for reducing injuries of the fetlock bones in Thoroughbred racehorses

“…Although often resulting in a mild, multi‐limb lameness, many racehorses are able to continue to train and race successfully with fetlock fatigue injury. Studies suggest that catastrophic musculoskeletal injures are a rare event at the race start level 6‐11 . However, reliance solely on race start data is flawed as it fails to capture prevalence of injuries sustained in training.…”

The development of safe and effective rehabilitation protocols for horses

“…If neuromuscular coordination, strength, and endurance are inadequately restored, then ligaments, muscles, and bones are exposed to greater or abnormal tissue loading that places repaired tissues at risk for reinjury (Brandt 2004). The role of stall rest or confinement must also be considered in the context of altered bone remodelling and soft tissue deconditioning in horses that have a high mental drive to compete or race (Hitchens et al 2018). Finally, clearly defined rehabilitation priorities and goals need to be established and followed throughout the treatment period.…”