Clodronate improves lameness in horses without changing bone turnover markers.
Authors: Mitchell A, Wright G, Sampson S N, Martin M, Cummings K, Gaddy D, Watts A E
Journal: Equine veterinary journal
Summary
Clodronate, a bisphosphonate commonly used clinically for lameness in performance horses, lacks robust evidence supporting its mechanism of action, prompting Mitchell and colleagues to investigate whether a single therapeutic dose altered bone remodelling, bone cell activity, and lameness in twelve university competition horses diagnosed with navicular syndrome. Using a randomised, blinded, placebo-controlled design, the researchers administered either 1.4 mg/kg clodronate or saline to six horses each, then monitored forelimb and hindlimb lameness at multiple timepoints over eight weeks alongside serum bone turnover markers (CTX-I and osteocalcin) and in vitro bone marrow cell recruitment. Treated horses showed statistically significant lameness improvement in the forelimb one week post-treatment (P = 0.005) and coaches documented significantly better ridden performance at week eight (P = 0.01), yet neither group demonstrated changes in bone turnover markers or bone cell recruitment, suggesting clodronate's therapeutic benefit operates through a mechanism independent of measurable bone remodelling suppression. The findings challenge assumptions about how bisphosphonates improve clinical outcomes in navicular disease and highlight the need for investigation into repeated dosing protocols and alternative anti-inflammatory or analgesic pathways. For practitioners considering clodronate as an adjunctive treatment for forelimb lameness in performance horses, this evidence provides modest support for efficacy whilst indicating that bone-protective mechanisms alone do not explain the clinical response.
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Practical Takeaways
- •Clodronate appears clinically effective for improving forelimb lameness in navicular syndrome cases, with improvements noted within 1 week and sustained performance gains by 8 weeks
- •The improvement in lameness occurs without measurable effects on bone remodeling, suggesting clodronate's clinical benefit may involve mechanisms other than direct effects on bone turnover
- •Further research is needed on multiple-dose protocols, as this study examined only single-dose effects and bisphosphonates have long half-lives that may produce cumulative effects
Key Findings
- •Single clodronate dose (1.4 mg/kg) significantly reduced forelimb lameness 1 week post-treatment (P = 0.005) in horses with navicular syndrome
- •Coaches reported significant improvement in ridden performance in clodronate-treated horses versus control at week 8 (P = 0.01)
- •Clodronate treatment produced no detectable changes in bone turnover markers (CTX-I and osteocalcin) or in vitro bone cell recruitment
- •No significant differences in hindlimb lameness were observed between treatment and control groups