Natural eggshell membrane supplementation for chronic lameness in warmblood horses: a 12-week prospective before–after study

Introduction Osteoarthritis is a leading cause of equine lameness, yet pragmatic evidence for nutraceuticals in horses remains limited. Methods We prospectively evaluated 12 weeks of daily natural eggshell membrane (NEM; 12 mg/kg, orally) supplementation in Warmblood horses with chronic lameness using a single-arm before–after design. Ten horses were enrolled and prespecified paired contrasts compared visit 3 (V3, week 12) with baseline (V1). Outcomes included rider-reported under-saddle function (walk and trot), examiner-graded lameness (rest and walk–trot composite), simple joint-angle kinematics (degrees), and owner-rated palatability. Results Rider-reported function improved by approximately half a grade at both walk and trot, and owner-rated palatability improved markedly. Examiner walk-trot scores showed a small trend toward improvement, while rest lameness remained unchanged. Statistical inference supported these patterns, with 95% confidence intervals (CIs) excluding zero for rider scores (Δ = −0.50) and palatability (Δ = −1.50). Moderate changes were observed in right-fore joint angle (Δ = +3.06°) and examiner composite grades (Δ = −0.11). These effects were supported by small-sample inference (permutation tests, bootstrap CIs) and complementary Bayesian estimation. Discussion and conclusion NEM showed potential short-term improvements in owner-reported function and examiner-graded gait, but larger controlled studies are needed.