Gross post-mortem and histological features in 27 horses with confirmed lumbosacral region pain and five control horses: A descriptive cadaveric study.
Authors: Quiney Laura, Stewart Jennifer, Routh Jennifer, Dyson Sue
Journal: Equine veterinary journal
Summary
# Lumbosacral Pain in Horses: Pathological Complexity Revealed Through Post-Mortem Examination Understanding why horses develop lumbosacral region pain has proven challenging, largely because clinical signs don't always correlate with imaging findings. Quiney and colleagues examined the cadaverous tissues of 27 horses with confirmed sacroiliac joint pain (diagnosed via response to local anaesthetic infiltration) and five controls with pain originating elsewhere, conducting detailed gross and histological assessments of the lumbosacral spine, pelvis, and associated nerve tissues. The affected group showed substantially greater nerve pathology, with discolouration of the sciatic or obturator nerves present in 26% of affected horses versus none in controls, and severe histological abnormality scores nearly eight times more prevalent (22% versus 3%). Beyond neural involvement, affected horses exhibited a striking range of osseous variants and degenerative changes—including sacroiliac enthesopathy, lumbosacral joint pitting lesions, sacral morphological asymmetries, and articular process ankylosis—far more frequently than controls. These findings suggest that lumbosacral pain is multifactorial, potentially involving nerve tissue inflammation or compression, entheseal disease, and biomechanical stress from anatomical variation, rather than a single discrete pathology. For practitioners, this reinforces the need for thorough assessment combining clinical response to diagnostic anaesthesia with consideration of predisposing structural factors; recognising neural involvement may also justify specific treatment approaches beyond joint-focused interventions.
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Practical Takeaways
- •Lumbosacral region pain has a multifactorial pathophysiological basis including nerve tissue damage and osseous abnormalities; diagnostic anaesthesia of the sacroiliac joint region helps identify affected horses but does not reveal the underlying cause
- •Nerve tissue histological changes are more common in horses with confirmed lumbosacral pain, suggesting neural involvement should be considered in treatment planning
- •Many osseous variants are naturally occurring; their presence alone does not confirm clinical disease, so correlation with clinical signs and response to local anaesthetic infiltration is essential for diagnosis
Key Findings
- •Gross discolouration of sciatic or obturator nerves was observed in 26% (7/27) of affected horses but no control horses
- •Grade 3/3 histological abnormality scores were present in 22% of nerve sections from affected horses versus 3% from control horses
- •Multiple osseous variants and abnormalities including sacroiliac enthesopathy, lumbosacral symphyseal periarticular modelling, and articular process joint abnormalities were more frequently observed in affected horses
- •Both control and affected horses may have had preclinical abnormalities, suggesting lumbosacral pain may reflect multiple pathological changes with neural pain playing an important role in some horses