A Randomized Blinded Crossover Clinical Trial to Determine the Effect of an Oral Joint Supplement on Equine Limb Kinematics, Orthopedic, Physiotherapy, and Handler Evaluation Scores

Highlights

• Blinded, placebo-controlled crossover study to determine effect of joint supplement.

• Horse limb kinematics, clinical orthopedic, physiotherapy, and handler evaluation.

• Supplement S or placebo was fed to 24 horses for 21 days each.

• S associated with improved kinematics, orthopedic, physiotherapy, and handler grade.

• Potential benefit to use of supplement S in clinical patients during rehabilitation.

Abstract

Despite the range of oral joint supplements available, there has been very limited research into their efficacy. The study aimed to determine the effect of an oral joint supplement on limb kinematics, orthopedic, physiotherapy, and handler evaluation in horses. Supplement S or placebo P was fed to 24 horses for 21 days each in a random order. Horses were evaluated at days 0 (baseline), 21 (after first treatment), and 42 (after second treatment). Assessments included the following: clinical orthopedic evaluation for straight line/lunging circle in walk and trot; high-speed motion capture determined hindlimb kinematics for straight-line trotting; grading of limb range of motion (ROM) and muscle tone based on standardized physiotherapy criteria; handler grading of specific criteria during pasture, groundwork, and ridden exercise. Effect of treatment, sequence, limb, and interactions were investigated using linear-mixed models. S was associated with significantly lower lameness grade in a straight line (P = .001) and circle (P = .010), with individual horses improving up to 2/10 grades over P/baseline. S was associated with significantly improved ROM and muscle tone. Ridden/groundwork scores were significantly higher with S compared to P/baseline. With S, horses were graded significantly higher for “ease of movement” at pasture compared with P/baseline. For horses with hindlimb lameness, S was associated with significantly greater tarsal flexion than baseline (4.2% greater, P < .020) or P (2.7% greater, P < .037). S was associated with less lameness and improved physiotherapy scores, ridden/groundwork scores, and pasture “ease of movement.” Increased midstance tarsal flexion of lame limbs may indicate improved mobility/comfort during peak loading, supporting a positive effect of S.

Introduction

Most horses are required to perform an athletic function. As athletic and nonathletic horses have a high incidence of lameness and orthopedic problems [1], [2], [3], [4], [5], [6], [7], [8], veterinarians, owners, riders, and trainers often select oral nutraceuticals or “joint supplements” to potentially improve performance or manage low-grade orthopedic problems [9], [10]. In vitro work suggests a rationale for use of various constituents of joint supplements, and clinical experience suggests that there may be benefits to oral administration of some products. However, there are very few well-designed studies investigating the clinical effects of joint supplements [11], [12], [13].

Investigation of the effect of a supplement can be challenging. Previous equine clinical studies evaluating oral joint supplements have largely been limited to owner assessment of improvement, sometimes without a control group and often in variable exercise. Controlling for these variables and using blinded assessment in a crossover design makes it more feasible to investigate the effect of a supplement. Horses with altered comfort levels could potentially demonstrate alterations in behavior and ease of work, flexibility, and muscle tone which could be assessed by blinded graded evaluation of these parameters. In addition, assessment of alterations in gait and movement can be done subjectively and objectively. Using a grading scale for lameness is an accepted method of detection of alterations in gait and loading, and recent studies have shown that specific gait features are detected by experienced evaluators [14], [15]. There may therefore be a potential benefit to grading of specific gait features. More objective evaluation of gait in horses with lameness has demonstrated that there are alterations in limb kinematics compared with horses without lameness [16], [17]. It would therefore be expected that use of a supplement that altered a horse's gait, and reduced lameness, would be detectable using subjective evaluation and also objective evaluation specifically investigating gait features that are associated with lameness.

The aim of this study was to determine the effect of an oral joint supplement (supplement S) on clinical orthopedic parameters, limb kinematics, and on physiotherapy and handler evaluation parameters in horses with low-grade lameness (≤4/10) using each horse as its own control. It was hypothesized that supplement S would result in reduced lameness grade, improved grade for gait parameters, altered limb kinematics, better physiotherapy range of motion (ROM) and muscle tone, and improved handler grading of movement.