Osteopathic Insights into Post-Castration Complications

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Castration is the most commonly performed surgical procedure in equine practice. It is also one of the most routinely dismissed when it comes to long-term consequences. The scar heals, the horse goes back to work, and the surgical site is rarely examined again. Yet equine osteopaths have long observed that geldings sometimes present with unexplained movement asymmetries, hindlimb stiffness, and pelvic dysfunction that conventional diagnostics cannot explain — and that often improve when the castration site is addressed. Pauline Bürgermeister decided to put that clinical intuition to the test. This thesis presents an original study of 25 geldings — a mix of Standardbred trotters and riding school horses — in which castration scars were systematically assessed for five clinical signs: depression of the scar tissue, fibrotic scarring, pain on palpation, discharge, and oedema. Gait asymmetry was evaluated using Sleip AI, a validated markerless motion analysis system, capturing head, pelvic, and total asymmetry scores. The results are striking. The composite clinical score showed a strong positive correlation with pelvic asymmetry (ρ = 0.71, p < 0.001) and a moderate correlation with total asymmetry (ρ = 0.53, p = 0.007). Tissue depression, fibrotic scarring, and oedema were the most influential individual signs. Pain alone did not reach significance — suggesting that the most clinically relevant changes are structural and chronic rather than acutely painful. Discharge appeared to dilute the composite score, highlighting the importance of weighting variables appropriately in future work. The thesis contextualises these findings within osteopathic anatomy, examining how fascial restriction, impaired lymphatic drainage, and the well-documented formation of neuromas in spermatic cord remnants might mechanically and neurologically contribute to pelvic dysfunction. The study is honest about its limitations — small sample, no blinded assessment, heterogeneous population — and frames its findings as a call to action rather than a conclusion. For any practitioner encountering unexplained hindlimb asymmetry in a gelding, this work offers a compelling reason to look further down the leg.