Efficacy of an oral chondroprotective joint supplement on stride length and lameness in aged geldings with osteoarthritis

Abstract

With osteoarthritis (OA) diagnosed in over 50% of horses aged 15 years or older, there is a drive within the industry to prevent, mitigate, or repair joint damage. As such, oral joint supplements (OJS) are one of the most popular feed additives fed by horse owners. Though extensively reviewed in in vitro studies, conclusive evidence of the efficacy of these nutraceuticals in vivo has yet to be found. Hypothesizing that OJS do not improve signs of OA, this study aimed to investigate the impacts of OJS on equine lameness. To do so, 40 geldings (aged 18 ± 7 yr) with OA and AAEP lameness grades between 2 and 4 (as scored by a board-licensed veterinarian) were enrolled in the study. Horses were striated by lameness grade, BCS, and weight, and then were randomly assigned to receive a placebo powder or OJS containing glucosamine hydrochloride, methylsulfonylmethane, sodium chondroitin sulfate, and avocado/soybean unsaponifiables added to a ration balancer for 6 wk. Both the ration balancer and OJS were fed according to product instructions. Placebo and OJS groups were color-coded to ensure researchers remained blinded to treatment, and horses were assigned a random numeric identifier to prevent bias. Stride length (SL) measurements, flexion tests (FT), and lameness locator (LL) assessments were performed every 2 wk. Statistical analysis was performed using PROC MIXED in SAS 9.4 with the fixed effect of treatment, day, treatment by day, and random effect of horse. Day 0 was a significant covariate for LL data and was included in the model. There was no effect of treatment or treatment by day interaction for SL, though day affected both walk (P = 0.04) and trot (P < 0.01). However, across days, all changes in stride length were within 3% of baseline measurements. Similarly, there was no effect of treatment or the interaction of treatment by day for FT scores. Day affected FT scores, with the lowest average score on d 28 (P = 0.04). Analysis of lameness locator data showed no evidence of supplementation improving forelimb or hindlimb lameness over time, though hindlimb lameness tended to differ on d 14, with OJS horses having greater indication of lameness (P = 0.09). Thus, 6 wk of feeding an OJS did not impact stride length, lameness, or gait symmetry though values of each measure changed over time regardless of treatment. As such, there is no evidence to support efficacy of the tested OJS. These results emphasize the importance of well-controlled studies to determine the OJS efficacy in vivo and support the continued development of evidence-based management strategies for horses diagnosed with OA.