Lameness is an important and prevalent medical condition in horses1 and accounts for up to $1 billion in losses for the US equine industry annually.2 Horses with subclinical or mild lameness have suboptimal performance,3,4 and mild lameness is often a precursor to severe or catastrophic musculoskeletal injury. Therefore, detection of horses with subclinical or mild lameness is important so that measures can be taken to correct or alleviate the lameness and thereby improve the welfare of affected horses. Additionally, sensitive methods are needed for assessment of lame horses following treatment to determine when an individual horse can safely return to prelameness activity or exercise without risking reinjury.
In horses, lameness is typically detected and monitored by means of a subjective lameness examination, in which horses are visually assessed at both a walk and a trot before a lameness grade, or score, is assigned.5 Unfortunately, results of multiple studies6–9 suggest that the use of subjective lameness scoring systems is not clinically reliable for identification of lame horses, especially when the lameness is mild. Furthermore, in 1 study,6 investigators identified inherent bias in subjective lameness scores following administration of perineural anesthesia. Thus, adjunct methods that are more sensitive and objective than the subjective lameness examination are necessary for detection and monitoring of horses with mild lameness and assessment of lame horses after administration of perineural anesthesia. Because horses with mild or moderate lameness are frequently not perceptibly lame at a walk,5 they are often not extensively examined at that gait during a subjective lameness examination. However, effective evaluation of lameness in horses at a walk would be beneficial, particularly for those in which observation at a gait faster than a walk might be detrimental.
Multiple studies10–14 have been conducted to evaluate the efficacy of objective methods, such as kinetics and kinematics, for the detection of lameness in horses at both a walk and a trot. Results of studies10–12 suggest that the use of stationary force platform kinetic and optical kinematic systems is just as sensitive as or more sensitive than subjective lameness examination performed by experienced equine veterinarians for diagnosing mild lameness in horses that are trotting. Few studies have been conducted to evaluate the efficacy of kinetic or kinematic methods for detecting subclinical or mild lameness in horses at a walk. In 1 study,13 horses in which mild lameness at a trot but no detectable lameness at a walk was induced had significant changes in hoof kinetics, compared with hoof kinetics obtained prior to lameness induction. Investigators of another study14 reported that optical kinematic values of the hoof were altered from prelameness values for horses in which mild to moderate lameness at a walk was induced. In clinically normal horses with unilateral, weight-bearing forelimb lameness, alterations in hoof kinematics occur in both the lame and nonlame limbs at a trot12; therefore, alterations in hoof kinematics may also occur at a walk, and characterization of those changes might be beneficial for the diagnosis of lameness in horses.
The objectives of the study reported here were to determine kinematic changes to the hoof of horses at a walk after induction of unilateral, weight-bearing forelimb lameness that was perceptible only at a trot and to determine whether hoof kinematics return to prelameness (baseline) values after perineural anesthesia. We hypothesized that after lameness induction, kinematic variables would vary from baseline values and between the lame and nonlame forelimbs for various segments of the stride when horses were walking, and that kinematic variables would return to values similar to those at baseline after perineural anesthesia. Our goal was to identify specific kinematic variables that were substantially altered at a walk by lameness during predefined segments of the stride.
H3-IMU, MEMSense LLC, Rapid City, SD.
Volant, Peak Performance Technologies Inc, Centennial, Colo.
Vicon-Motus, version 9.2, Vicon Motion Systems Inc, Centennial, Colo.
MEK 92-PAD photoelectric control, Mekontrol Inc, Northboro, Mass.
STATA, version 11, StataCorp LP, College Station, Tex.
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