Osseous spinal pathology and epaxial muscle ultrasonography in Thoroughbred racehorses
Authors: STUBBS N. C., RIGGS C. M., HODGES P. W., JEFFCOTT L. B., HODGSON D. R., CLAYTON H. M., Mc GOWAN C. M.
Journal: Equine Veterinary Journal
Summary
# Editorial Summary: Osseous Spinal Pathology and Epaxial Muscle Ultrasonography in Thoroughbred Racehorses The deep stabilising muscles of the equine spine, particularly the multifidus, are critical for maintaining spinal integrity during athletic work, yet their relationship to structural spinal lesions has remained largely unexplored in horses despite well-documented associations in human and veterinary small animal medicine. Stubbs and colleagues used high-frequency ultrasound to measure the cross-sectional area (CSA) of multifidus and sacrocaudalis dorsalis muscles at five thoracolumbosacral levels in 22 Thoroughbreds presented for euthanasia, comparing these measurements to detailed post-mortem grading of osseous pathology across the same spinal regions. All horses demonstrated significant left-right asymmetry in multifidus CSA at multiple levels (mean >2 sites per horse), with L5 most commonly affected, and critically, 16 of 17 horses with severe (grade 3) pathological changes exhibited ipsilateral muscle atrophy corresponding precisely to the side of the lesion. This consistent association between asymmetrical osseous pathology and measurable muscle atrophy suggests that ultrasound assessment of multifidus symmetry could serve as a practical diagnostic aid for identifying clinically significant spinal disease in performance horses. For practitioners managing horses with suspected back problems, this work provides evidence that objective ultrasonic evaluation of epaxial muscle morphology may help localise pathology and could complement clinical and radiographic findings in formulating treatment strategies.
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Practical Takeaways
- •Ultrasonographic measurement of multifidus muscle symmetry may help identify racehorses with underlying spinal pathology, particularly at the lumbosacral region
- •Marked asymmetry of the multifidus muscle on ultrasound warrants further investigation for osseous spinal pathology using imaging (radiography, scintigraphy, or advanced imaging)
- •This technique could complement clinical examination in back problem investigations in racing Thoroughbreds without requiring advanced imaging modalities
Key Findings
- •All 22 horses demonstrated significant left/right asymmetry of multifidus cross-sectional area at ≥2 spinal levels, most commonly at L5 (74 sites affected total)
- •16 of 17 horses (94%) with severe grade 3 osseous pathology showed ipsilateral multifidus or sacrocaudalis dorsalis atrophy
- •Significant association found between severity of osseous pathological grade and degree of multifidus asymmetry (p<0.05)