Biometric sensors may help identify the few Thoroughbreds at highest risk for fatal musculoskeletal injury

A retrospective study published in the Journal of the American Veterinary Medical Association evaluated whether accelerometer‑based inertial measurement unit (IMU) sensors could identify racehorses at increased risk for fatal musculoskeletal injury (FMI). Investigators analyzed stride data from 28,481 starts by 11,834 Thoroughbreds at 10 US tracks from July 2021 through May 2024.¹ Sensors (StrideSAFE) recorded three‑axis acceleration at 800 Hz from a pocket in the saddle cloth; a machine‑learned algorithm then assigned each run a risk score from 1 (lowest) to 6 (highest).

Seventy‑four horses sustained an FMI within 120 days of scoring. Horses assigned a highest score of 6 made up only 122 starts (0.4% of starts) but were 44.6 times more likely to sustain an FMI than horses scored as 1. Approximately 4% of horses with a score of 6 incurred an FMI within 120 days (about 1 in 25 in that group). Fetlock‑region fractures accounted for 65% of FMIs in the cohort, and every horse in the highest risk category that later suffered an FMI sustained a fetlock fracture.¹

Associated factors

Multivariable analysis identified several associated factors. Intact males were more likely to receive higher risk scores than females. Shorter race distances were associated with higher risk‑score assignments (the highest‑risk group had a mean race distance of ~1,372 ± 237 m). The probability of FMI was lower on synthetic all‑weather surfaces compared with dirt and turf; dirt races comprised roughly 55% of starts in the dataset.¹

Clinical relevance and practical workflow

Authors and the AVMA frame the IMU‑plus‑algorithm system as a screening or triage tool rather than a diagnostic test.² The system functions as a “check engine light,” enriching for horses that warrant expedited clinical evaluation, targeted lameness examination, and selective advanced imaging (for example, standing PET or targeted CT/MRI of the fetlock). Because RS‑6 assignments were rare (122 over ~145 weeks across 10 tracks, averaging <1 RS‑6 case per week), concentrating advanced diagnostics on this small group is operationally feasible and could optimize use of limited veterinary resources.¹

Bottom line

IMU‑based monitoring with machine‑learned risk scoring can identify a tiny subset of Thoroughbreds at elevated relative risk of catastrophic musculoskeletal injury. Clinicians should interpret algorithmic risk scores alongside clinical exam and imaging, recognize the modest absolute risk among RS‑6 horses, and confirm funding and conflict‑of‑interest disclosures in the published manuscript prior to large‑scale adoption.

References

1. Mc Sweeney D, Wang Y, Palmer SE, et al. Thoroughbreds deemed to be most at risk by inertial measurement unit sensors suffered a fatal musculoskeletal injury at a higher rate than other racehorses. J Am Vet Med Assoc. Published online 2025. doi:10.2460/javma.25.04.0268.
2. American Veterinary Medical Association. New technology could help reduce fatal injuries in horse races. AVMA news/press release. Accessed November 13, 2025. https://www.avma.org/news/press-releases/new-technology-could-help-reduce-fatal-injuries-horse-races