Clinically relevant doses of tiludronate do not affect bone remodelling in pasture-exercised horses.

Abstract

Bisphosphonates are widely used in equine athletes to reduce lameness associated with skeletal disorders. Widespread off-label use has led to concern regarding potential negative effects on bone healing, but little evidence exists to support or refute this. To investigate the influence of clinically relevant doses of tiludronate on bone remodelling and bone healing. Randomised, controlled in vivo experiments. Each horse had a single tuber coxae biopsied (Day 0), then were divided into a treatment (IV tiludronate) or control (IV saline) group. Treatments were administered 30 and 90 days following initial biopsy. Biopsy of the tuber coxae was repeated on Day 60 to evaluate bone healing following a single treatment. Oxytetracycline was administered on Days 137 and 147 to label bone formation. The contralateral tuber coxae was biopsied on Day 150 to evaluate effects of repeated treatment. Bone biopsies were evaluated with micro-computed tomography and/or dynamic histomorphometry using standard techniques. Nineteen horses completed the study, with no complications following the biopsies and treatments. No significant differences in the trabecular bone parameters or bone formation rate were observed between treatment groups. The use of a first-generation bisphosphonate may mean some effects of these drugs are underrepresented using this model. The results pertain to the tuber coxae and may not reflect injury or the healing response that occurs in long bones in training or racing. In this model, tiludronate did not affect normal bone remodelling in the horse, despite repeat dosages.