Published Papers

Comparison of an inertial sensor system of lameness quantification with subjective lameness evaluation. McCracken, M. J.; Kramer, J.; Keegan, K. G.; Lopes, M.; Wilson, D. A.; Reed, S. K.; LaCarrubba, A.; Rasch, M.; Wiley-Blackwell, Oxford, UK, Equine Veterinary Journal, 2012, 44, 6, pp 652-656, 20 ref.


Comparison of an inertial sensor system with a stationary force plate for evaluation of horses with bilateral forelimb lameness. Keegan, K. G.; MacAllister, C. G.; Wilson, D. A.; Gedon, C. A.; Kramer, J.; Yonezawa, Y.; Maki, H.; Pai, P. F.; American Veterinary Medical Association, Schaumburg, USA, American Journal of Veterinary Research, 2012, 73, 3, pp 368-374, 28 ref.


Assessment of repeatability of a wireless, inertial sensor-based lameness evaluation system for horses. Keegan, K. G.; Kramer, J.; Yonezawa, Y.; Maki, H.; Pai, P. F.; Dent, E. V.; Kellerman, T. E.; Wilson, D. A.; Reed, S. K.; American Veterinary Medical Association, Schaumburg, USA, American Journal of Veterinary Research, 2011, 72, 9, pp 1156-1163, 20 ref.


Objective assessment of lameness.
Keegan, K. G.; Baxter, G. M.; John Wiley & Sons, Chichester, UK,
Adams and Stashak’s lameness in horses, 2011, Ed.6, pp 154-164, 19 ref.


Kinematics/kinetics.
Keegan, K. G.; Baxter, GE. M.; John Wiley & Sons, Chichester, UK,
Adams and Stashak’s lameness in horses, 2011, Ed.6, pp 165-172, 15 ref.


Gait Analysis and Quantification of Lameness.
Keegan, K.G.; Ross, M.W. and Dyson, S.J.; Elsevier Saunders, St. Louis, MO, USA.
Diagnosis and Management of Lameness in the Horse, 2011, Ed. 2, pp 245-251, 85 ref.


The Lameness Locator (wireless inertial sensors for detection of lameness in horses). Keegan, K. G.; Vezzoni, A.; Taravella, E.; European Society of Veterinary Orthopaedics and Traumatology, Cremona, Italy, Proceedings, 3rd World Veterinary Orthopaedic Congress, ESVOT-VOS, 15th ESVOT Congress, Bologna, Italy, 15-18 September, 2010, 2010, pp 215-217


Repeatability of subjective evaluation of lameness in horses.
Keegan, K. G.; Dent, E. V.; Wilson, D. A.; Janicek, J.; Kramer, J.; Lacarrubba, A.; Walsh, D. M.; Cassells, M. W.; Esther, T. M.; Schiltz, P.; Frees, K. E.; Wilhite, C. L.; Clark, J. M.; Pollitt, C. C.; Shaw, R.; Norris, T.; Wiley-Blackwell, Oxford, UK,
Equine Veterinary Journal, 2010, 42, 2, pp 92-97, 23 ref.

Reasons for performing study: Previous studies have suggested that agreement between equine veterinarians subjectively evaluating lameness in horses is low. These studies were limited to small numbers of horses, evaluating movement on the treadmill or to evaluating previously-recorded videotape. Objectives: To estimate agreement between equine practitioners performing lameness evaluations in horses in the live, over ground setting. Methods: 131 mature horses were evaluated for lameness by 2-5 clinicians (mean 3.2) with a weighted-average of 18.7 years of experience. Clinicians graded each limb using the AAEP lameness scale by first watching the horse trot in a straight line only and then after full lameness evaluation. Agreement was estimated by calculation of Fleiss’ (κ). Evaluators agreed if they picked the same limb as lame or not lame regardless of the severity of perceived lameness. Results: After only evaluating the horse trot in a straight line clinicians agreed whether a limb was lame or not 76.6% of the time (κ=0.44). After full lameness evaluation clinicians agreed whether a limb was lame or not 72.9% of the time (κ=0.45). Agreement on forelimb lameness was slightly higher than on hindlimb lameness. When the mean AAEP lameness score was >1.5 clinicians agreed whether or not a limb was lame 93.1% of the time (κ=0.86), but when the mean score was ≤1.5 they agreed 61.9% (κ=0.23) of the time. When given the task of picking whether or not the horse was lame and picking the worst limb after full lameness evaluation, clinicians agreed 51.6% (κ=0.37) of the time. Conclusions: For horses with mild lameness subjective evaluation of lameness is not very reliable. Potential relevance: A search for and the development of more objective and reliable methods of lameness evaluation is justified and should be encouraged and supported.


Agreement among veterinarians for subjective evaluation of lameness in horses.
Keegan, K. G.; Dent, E. V.; Wilson, D. A.; Janicek, J.; Kramer, J.; LaCarrubba, A.; Walsh, D. M.; Cassels, M. W.; Ester, T. M.; Schiltz, P.; Frees, K. E.; Wilhite, C. L.; Clark, J. M.; Pollitt, C. C.; Shaw, R.; Norris, T.; Werner, H. W.;
American Association of Equine Practitioners (AAEP), Lexington, USA, Proceedingsof the 54th Annual Convention of the American Association of Equine Practitioners, San Diego, California, USA, 6-10 December 2008, 2008, pp 260.


Keegan, K. G. , Messer, N. T. , Reed, S. K. , Wilson, D. A. , Kramer, J.
American Journal of Veterinary Research, 2008, Vol. 69, No. 2, pp. 167-173, 26 ref.

Objective – To determine the effectiveness of administering multiple doses of phenylbutazone alone or a combination of phenylbutazone and flunixin meglumine to alleviate lameness in horses. Animals – 29 adult horses with naturally occurring forelimb and hind limb lameness. Procedures – Lameness evaluations were performed by use of kinematic evaluation while horses were trotting on a treadmill. Lameness evaluations were performed before and 12 hours after administration of 2 nonsteroidal anti-inflammatory drug (NSAID) treatment regimens. Phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, every 12 hours for 5 days, or phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, every 12 hours for 5 days in combination with flunixin meglumine administered at 1.1 mg/kg, IV, every 12 hours for 5 days. Results – Alleviation of lameness was greater after administration of the combination of NSAIDs than after oral administration of phenylbutazone alone. Improvement in horses after a combination of NSAIDs did not completely mask lameness. Five horses did not improve after either NSAID treatment regimen. All posttreatment plasma concentrations of NSAIDs were less than those currently allowed by the United States Equestrian Federation Inc for a single NSAID. One horse administered the combination NSAID regimen died of acute necrotizing colitis during the study. Conclusions and Clinical Relevance – Administration of a combination of NSAIDs at the dosages and intervals used in the study reported here alleviated the lameness condition more effectively than did oral administration of phenylbutazone alone. This may attract use of combinations of NSAIDs to increase performance despite potential toxic adverse effects.


Evidence-based lameness detection and quantification.

Keegan, K. G.
Editor:Ramey, D. W.
Veterinary Clinics of North America, Equine Practice, 2007, Vol. 23, No. 2, pp. 403-423, 53 ref

Kinematic and kinetic gait analysis potentially offers veterinarians an objective method of determining equine limb lameness. Subjective analyses have been shown to be somewhat flawed, and there does not seem to be a high degree of intraobserver agreement when evaluating individual horses. In addition, recognition of the compensatory effects of primary lameness may be helpful for the practicing equine veterinarian.


Head movement pattern in horses with forelimb and hindlimb lameness.

Keegan, K. G. 
Editor:
Brokken, T. D.
Proceedings of the 51st Annual Convention of the American Association of Equine Practitioners, Seattle, Washington, USA, 3-7 December, 2005, 2005,pp. 114-120, 14 ref.

The vertical head movement pattern in horses with forelimb lameness may contain information useful for determining the instant of peak pain within the stride cycle. This information may be helpful to the practitioner in isolating lameness within the affected limb.


Pelvic movement pattern in horses with hindlimb and forelimb lameness.

Keegan, K. G. 
Editor:
Brokken, T. D.
Proceedings of the 51st Annual Convention of the American Association of Equine Practitioners, Seattle, Washington, USA, 3-7 December, 2005, 2005,pp. 121-127, 9 ref.

Kelmer G, Keegan KG, Kramer J, Wilson DA, Pai PF, Singh P. Computer-assisted kinematic evaluation of induced compensatory lameness in horses trotting on a treadmill. American Journal of Veterinary Research 66(4);646-655, April 2005.


The vertical pelvic movement patterns in horses with hindlimb lameness may contain information useful for determining the instant of peak pain within the stride cycle. This information may be helpful to the practitioner in isolating lameness within the affected limb.


How to evaluate head and pelvic movement to determine lameness.

Keegan, K. G. , Wilson, D. A. , Kramer, J.
Proceedings of the 50th Annual Convention of the American Association of Equine Practitioners, Denver, Colorado, USA, 4-8 December, 2004, 2004,pp. 206-211, 9 ref.


Kinematics of lameness.

Kramer, J. , Keegan, K. G.
Editor:Hinchcliff, K. W., Kaneps, A. J. , Geor, R. J.
Equine sports medicine and surgery: basic and clinical sciences of the equine athlete, 2004, pp. 231-246, 55 ref.


Objective determination of pelvic movement during hind limb lameness by use of a signal decomposition method and pelvic height differences.

Kramer, J. , Keegan, K. G. , Kelmer, G. , Wilson, D. A.
American Journal of Veterinary Research, 2004, Vol. 65, No. 6, pp. 741-747, 19 ref.

Objective – To evaluate pelvic movement over a large number of strides in sound horses and in horses with induced hind limb lameness by applying methods to the pelvis that have been described for evaluating vertical head movement in horses with induced forelimb lameness. Animals – 17 adult horses. Procedure – Horses were filmed while trotting on a treadmill before and after induction of transient mild and moderate hind limb lamenesses. Vertical pelvic movement was measured by a signal decomposition method. The vertical pelvic signal was decomposed into a periodic component (A1) that occurred at half the stride frequency (representing vertical pelvic movement caused by lameness) and another periodic component (A2) that occurred at stride frequency (representing normal vertical pelvic movement of a trotting horse). Vertical pelvic and foot positions were correlated for each stride to compare the difference between the minimum and maximum heights of the pelvis during and after stance of the right hind limb to the minimum and maximum heights of the pelvis during and after stance of the left hind limb. Results – Maximum pelvic height difference and lameness amplitude (A1) differed significantly between sound and mild or moderate hind limb lameness conditions. Mean A1 value for vertical pelvic movement in sound horses was less than that previously reported for vertical head movement. Conclusion and Clinical Relevance – Pelvic height differences and signal decomposition of pelvic movement can be used to objectively evaluate hind limb lameness in horses over a large number of strides in clinical and research settings.


Evaluation of a sensor-based system of motion analysis for detection and quantification of forelimb and hind limb lameness in horses.

Keegan, K. G. , Yonezawa, Y. , Pai, P. F. , Wilson, D. A. , Kramer, J.
American Journal of Veterinary Research, 2004, Vol. 65, No. 5, pp. 665-670, 21 ref.

Objective – To compare a sensor-based accelerometer-gyroscopic (A-G) system with a video-based motion analysis system (VMAS) technique for detection and quantification of lameness in horses. Animals – 8 adult horses. Procedure – 2 horses were evaluated once, 2 had navicular disease and were evaluated before and after nerve blocks, and 4 had 2 levels of shoe-induced lameness, alternatively, in each of 4 limbs. Horses were instrumented with an accelerometer transducer on the head and pelvis, a gyroscopic transducer on the right forelimb and hind feet, and a receiver-transmitter. Signals from the A-G system were collected simultaneously with those from the VMAS for collection of head, pelvis, and right feet positions with horses trotting on a treadmill. Lameness was detected with an algorithm that quantified lameness as asymmetry of head and pelvic movements. Comparisons between the A-G and VMAS systems were made by use of correlation and agreement (κ value) analyses. Results – Correlation between the A-G and VMAS systems for quantification of lameness was linear and high (r2=0.9544 and 0.8235 for forelimb and hind limb, respectively). Quantification of hind limb lameness with the A-G system was higher than measured via VMAS. Agreement between the 2 methods for detection of lameness was excellent (κ=0.76) for the forelimb and good (κ=0.56) for the hind limb. Conclusions and Clinical Relevance – The A-G system detected and quantified forelimb and hind limb lameness in horses trotting on the treadmill. Because the data are collected wirelessly, this system might be used to objectively evaluate lameness in the field.


Detection of lameness and determination of the affected forelimb in horses by use of continuous wavelet transformation and neural network classification of kinematic data.

Keegan, K. G. , Arafat, S. , Skubic, M. , Wilson, D. A. , Kramer, J. 
American Journal of Veterinary Research,
 2003, Vol. 64, No. 11, pp. 1376-1381, 24 ref.

Objective – To investigate continuous wavelet transformation and neural network classification of gait data for detecting forelimb lameness in horses. Animals – 12 adult horses with mild forelimb lameness. Procedure – Position of the head and right forelimb foot, metacarpophalangeal (ie, fetlock), carpal, and elbow joints was determined by use of kinematic analysis before and after palmar digital nerve blocks. We obtained 8 recordings from horses without lameness, 8 with right forelimb lameness, and 8 with left forelimb lameness. Vertical and horizontal position of the head and vertical position of the foot, fetlock, carpal, and elbow joints were processed by continuous wavelet transformation. Feature vectors were created from the transformed signals and a neural network trained with data from 6 horses, which was then tested on the remaining 2 horses for each category until each horse was used twice for training and testing. Correct classification percentage (CCP) was calculated for each combination of gait signals tested. Results – Wavelet-transformed vertical position of the head and right forelimb foot had greater CCP (85%) than untransformed data (21%). Adding data from the fetlock, carpal, or elbow joints did not improve CCP over that for the head and foot alone. Conclusions and Clinical Relevance – Wavelet transformation of gait data extracts information that is important for the detection and differentiation of forelimb lameness of horses. All of the necessary information to detect lameness and differentiate the side of lameness can be obtained by observation of vertical head movement in concert with movement of the foot of 1 forelimb.


Signal decomposition method of evaluating head movement to measure induced forelimb lameness in horses trotting on a treadmill.

Keegan, K. G. , Pai, P. F. , Wilson, D. A. , Smith, B. K. 
Equine Veterinary Journal,
 2001, Vol. 33, No. 5, pp. 446-451, 11 ref.

In horses at a trot, the head moves up and down twice in 1 stride. In horses with unilateral forelimb lameness this movement is asymmetric. Computer-assisted kinematic analysis of vertical head movement can be used to quantify objectively lameness in horses in clinical trials. However, in mild lameness, absolute measurements of vertical head height may not be sensitive enough to detect small differences in lameness, and extraneous head movement by the horse due to curiosity, excitement or nervousness interferes with the accurate measurement of vertical head movement asymmetry. We describe a simple, signal-decompensation method of evaluating vertical head movement using a model of induced mild foot lameness in 9 horses. The technique assumes that the vertical head movement pattern can be broken down into 3 components; the vertical head movement caused by forelimb lameness (A1), the amplitude of the natural biphasic vertical head movement (A2) and extraneous head movement. Extraneous head movement is mathematically removed from the vertical head movement pattern. A1 and A2 are then calculated. After induction of lameness, mean A1 increased by 1.63 cm (range 0.10-3.33 cm, P=0.005). Mean A2 did not significantly change after lameness induction. Error in reproduction of the original head movement pattern was 0.3-0.5%. We calculated that a hypothetical clinical trial would require 12 subjects for testing to be 80% certain that this difference would be successfully detected using this method of lameness evaluation.


Keegan KG, Pai PF, Wilson DA, Smith BK. A curve-fitting technique for evaluating head movement to measure forelimb lameness in horses. Biomedical Sciences Instrumentation 36 (ISA [International Society for Measurement and Control volume 395]:239-244, 2000.


Kinematics of the hind limb in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and intra-articular administration of anesthetic.

Kramer, J. , Keegan, K. G. , Wilson, D. A. , Smith, B. K. , Wilson, D. J. 
American Journal of Veterinary Research,
 2000, Vol. 61, No. 9, pp. 1031-1036, 30 ref.

8 healthy horses were examined to identify hind limb and pelvic kinematic variables that change in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and after subsequent intra-articular administration of anesthetic. Kinematic measurements were made before and after transient endotoxin-induced lameness of the distal intertarsal and tarsometatarsal joints and after intra-articular administration of anaesthetic. Fourteen displacement and joint angle (metatarsophalangeal [fetlock] and tarsal joints) measurements were made on the right hind limb, sacrum, and the right and left tubera coxae. Kinematic measurements were compared by general linear models, using a repeated measures ANOVA. Post hoc multiple comparisons between treatments were evaluated with a Fisher least squared difference test at α=0.05. After lameness induction, fetlock and tarsal joint extension during stance decreased, fetlock joint flexion and hoof height during swing increased, limb protraction decreased, and vertical excursion of the tubera coxae became more asymmetric. After intra-articular administration of anesthetic, limb protraction returned to the degree seen before lameness, and vertical excursion of the tubera coxae became more symmetric. It is concluded that increased length of hind limb protraction and symmetry of tubera coxae vertical excursion are sensitive indicators of improvement in tarsal joint lameness. When evaluating changes in tarsal joint lameness, evaluating the horse from the side (to assess limb protraction) is as important as evaluating from the rear (to assess pelvic symmetry).


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.

Keegan, K.G., Wilson, D.A., Wilson D.J., Smith B., Gaughan E.M., Pleasant R.S., Lillich J.D., Kramer K., Howard R.D., Bacon-Miller C., Davis E.G., May K.A., Cheramie H.S., Valentino W.L., van Harreveld P.D.
American Journal of Veterinary Research,
 1998, Vol. 59, No. 11, pp. 1370-1377, 35 ref.

The sensitivity and accuracy of subjective evaluation of mild lameness was evaluated in 19 lame and 5 healthy horses during treadmill locomotion. Lameness was evaluated by subjective score and kinematic analysis before and after palmar digital nerve block (PDNB) by 6 clinicians and 7 interns or residents. Within-observer agreement was within the range expected for conditions of moderate diagnostic difficulty and was higher for clinicians than for interns or residents. Between-observer agreement was acceptable for scores within 1 value of each other. Between-observer agreement of change in lameness score after PDNB was poor. When kinematic variables were ranked with each clinicians subjective change in score, only 2 were among the top 3 for the majority of clinicians. Asymmetry of vertical head movement between contralateral forelimb stance phases and the point of maximum hoof height during swing decreased as lameness subjectively improved. It is concluded that mild lameness may be difficult to evaluate during treadmill locomotion. Lack of agreement in scoring of mild lameness by clinicians emphasizes the need to use more objective measures for quantifying lameness.


Keegan KG, Yonezawa Y, Pai PF, Wilson DA. Telemeterized accelerometer-based system for the detection of lameness in horses. Biomedical Science Instrumentation 38 (ISA [International Society for Measurement and Control volume 419]:112, 2002.

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