Lameness is the most common medical problem in horses.1 When considering total cost of treatment and loss of use, it is also the most expensive.1 Even lameness of mild severity, if it adversely affects the performance or use of a horse, can be costly to the owner. Ideally, veterinary practitioners should be able to reliably detect and quantify lameness in horses at all severity levels. The current standard for lameness evaluation in horses is subjective grading by use of scales with discrete levels, such as the AAEP lameness scale.2 However, evidence suggests that subjective evaluation of lameness, even among experts, is only marginally acceptable for lameness of mild severity.3–6 Therefore, a search for and development of an objective and more reliable form of lameness evaluation in horses is a worthwhile endeavor.
Camera-based kinematic evaluation of movement on a treadmill and use of a stationary force plate are 2 techniques that have been tested and provide repeatable and accurate objective evaluation of lameness in horses.7–10 Camera-based kinematic evaluations are usually performed in a laboratory setting under carefully controlled conditions of lighting and background with predetermined locations and limited size of the field of view. The stationary force plate requires dedicated space and substantial technical expertise to use and maintain. Obtaining sufficient data for reproducible results also requires multiple hoof strikes on the small surface area of the plate, which requires time and patience. Although these techniques are useful investigative tools and are worth further study and development, they are not useful as a field-ready objective lameness evaluation technique for use by practicing equine veterinarians at this time.
A technique that has potential for development into an objective method of lameness evaluation for use in the field is wireless transmission of data from inertial sensors attached to the horse's body. Sensors can be designed that are small enough to be inconsequential to a horse's normal movement. Data logging and downloading collected data from inertial sensors have been reported in horses as early as 1994.11 In 2002, a method of wireless transmission of body-mounted inertial sensors for the specific purpose of lameness evaluation in horses was introduced.12 The study reported here represents an improvement of the system first reported in 2002, with further development by collaboration between equine veterinarians and electrical and mechanical engineers. The purpose of the study reported here was to determine the system's repeatability in uncontrolled conditions for the detection of movement variables useful in evaluation of lameness in horses.
American Association of Equine Practitioners
Difference in head maximum positions between right and left portions of the stride
Difference in head minimum positions between right and left portions of the stride
Head movement asymmetry
Difference in pelvis maximum positions between right and left portions of the stride
Difference in pelvis minimum positions between right and left portions of the stride
Pelvic movement asymmetry
3M Dual Lock Tape, ULine, Waukegan, Ill.
MMA7260QT, ± 1.5 to 6 g, Freescale Semiconductor, Austin Tex.
Gyrostar ENC-03M, Murata Electronics North America, Smyrna, Ga.
EYSF1SAJJ, Taiyo Yuden Co Ltd, Tokyo, Japan.
Hyper Power Co Ltd, Shenzhen, China.
PIC18LF452/PQ(44), Microchip Technology Inc, Chandler, Ariz.
Delphi, Borland Software Corp, Austin, Tex.
MATLAB, The Mathworks Inc, Natick, Mass.
USDA. National economic cost of equine lameness, colic, and equine protozoal myeloencephalitis in the United States. Information sheet No. N348.1001. Fort Collins, Colo: USDA APHIS Veterinary Services National Health Monitoring System, 2001.
Guide for veterinary service and judging of equestrian events. 4th ed. Lexington, Ky: American Association of Equine Practitioners, 1991;19.
Keegan KG, Wilson DA, Wilson DJ, et al. Evaluation of mild lameness in horses trotting on a treadmill by clinicians and interns or residents and correlation of their assessments with kinematic gait analysis. Am J Vet Res 1998; 59: 1370–1377.
Hewetson M, Christley RM, Hunt ID, et al. Investigations of the reliability of observational gait analysis for the assessment of lameness in horses. Vet Rec 2006; 158: 852–858.
Fuller CJ, Bladon BM, Driver AJ, et al. The intra- and inter-assessor reliability of measurement of functional outcome by lameness scoring in horses. Vet J 2006; 171: 281–286.
Arkell M, Archer RM, Guitian FJ, et al. Evidence of bias affecting the interpretation of the results of local anesthetic nerve blocks when assessing lameness in horses. Vet Rec 2006; 159: 346–349.
Symonds KD, MacAllister CG, Erkert RS, et al. Use of force plate analysis to assess the analgesic effects of etodolac in horses with navicular syndrome. Am J Vet Res 2006; 67: 557–561.
Ishihara A, Bertone AL, Rajala-Schultz PJ. Association between subjective lameness grade and kinetic gait parameters in horses with experimentally induced forelimb lameness. Am J Vet Res 2005; 66: 1805–1815.
Bucher HHF, Savelberg HCCM, Schamhardt HC, et al. Head and trunk movement adaptations in horses with experimentally induced for or hind limb lameness. Equine Vet J 1996; 28: 71–76.
Barrey E, Hermelin M, Vaudelin JL, et al. Utilisation of an accelerometric device in equine gait analysis. Equine Vet J Suppl 1994; 17: 7–12.
Keegan KG, Yonezawa Y, Pai PF, et al. Telemeterized accelerometer-based system for the detection of lameness in horses. Biomed Sci Instrum 2002; 38: 107–112.
Keegan KG, Pai PF, Wilson DA, et al. A curve-fitting technique for evaluating head movement to measure forelimb lameness in horses. Biomed Sci Instrum 2000; 36: 239–44.
Keegan KG, Pai PF, Wilson DA, et al. Signal decomposition method of evaluating head movement to measure induced forelimb lameness in horses trotting on a treadmill. Equine Vet J 2001; 33: 446–451.
Kramer J, Keegan KG, Kelmer G, et al. Objective determination of pelvic movement during hind limb lameness using a signal decomposition method and pelvic height differences. Am J Vet Res 2004; 65: 741–747.
Keegan KG, Dent EV, Wilson DA, et al. Repeatability of subjective evaluation of lameness in horses. Equine Vet J 2010; 42: 92–97.
Weishaupt MA, Schatzman U, Staub R. Quantification of supportive forelimb lameness by recording movements of the horse's head during exercise, using an accelerometer. Pferdeheilkunde 1993; 9: 375–377.
Church EE, Walker AM, Wilson AM, et al. Evaluation of discriminant analysis based on dorsoventral symmetry indices to quantify hindlimb lameness during over ground locomotion in the horse. Equine Vet J 2009; 4: 304–308.
Pfau T, Ferrari M, Parsons K, et al. A hidden Markov model-based stride segmentation technique applied to equine inertial sensor trunk movement data. J Biomech 2008; 41: 216–220.
Pfau T, Robilliard J, Weller R, et al. Assessment of mild hindlimb lameness during over ground locomotion using linear discriminant analysis of inertial sensor data. Equine Vet J 2008; 38: 407–413.