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Author |
McGuigan, M.P.; Wilson, A.M. |
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Title |
The effect of gait and digital flexor muscle activation on limb compliance in the forelimb of the horse Equus caballus |
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Journal Article |
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Year |
2003 |
Publication  |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
206 |
Issue |
Pt 8 |
Pages |
1325-1336 |
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Keywords |
Animals; Biomechanics; Forelimb/anatomy & histology/*physiology; Gait/*physiology; Horses/anatomy & histology/*physiology; Muscle Contraction/*physiology; Running |
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Abstract |
A horse's legs are compressed during the stance phase, storing and then returning elastic strain energy in spring-like muscle-tendon units. The arrangement of the muscle-tendon units around the lever-like joints means that as the leg shortens the muscle-tendon units are stretched. The forelimb anatomy means that the leg can be conceptually divided into two springs: the proximal spring, from the scapula to the elbow, and the distal spring, from the elbow to the foot. In this paper we report the results of a series of experiments testing the hypothesis that there is minimal scope for muscle contraction in either spring to adjust limb compliance. Firstly, we demonstrate that the distal, passive leg spring changes length by 127 mm (range 106-128 mm) at gallop and the proximal spring by 12 mm (9-15 mm). Secondly, we demonstrate that there is a linear relationship between limb force and metacarpo-phalangeal (MCP) joint angle that is minimally influenced by digital flexor muscle activation in vitro or as a function of gait in vivo. Finally, we determined the relationship between MCP joint angle and vertical ground-reaction force at trot and then predicted the forelimb peak vertical ground-reaction force during a 12 m s(-1) gallop on a treadmill. These were 12.79 N kg(-1) body mass (BM) (range 12.07-13.73 N kg(-1) BM) for the lead forelimb and 15.23 N kg(-1) BM (13.51-17.10 N kg(-1) BM) for the non-lead forelimb. |
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Address |
Structure and Motion Laboratory, Veterinary Basic Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK. m.p.mcguigan@leeds.ac.uk |
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0022-0949 |
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PMID:12624168 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3655 |
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Author |
Witte, T.H.; Knill, K.; Wilson, A.M. |
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Title |
Determination of peak vertical ground reaction force from duty factor in the horse (Equus caballus) |
Type |
Journal Article |
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Year |
2004 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
207 |
Issue |
Pt 21 |
Pages |
3639-3648 |
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Keywords |
*Acceleration; Animals; Biomechanics; Forelimb/physiology; *Gait; Hindlimb/physiology; Horses/*physiology; Locomotion/*physiology; Telemetry; Time Factors |
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Abstract |
Measurement of peak vertical ground reaction force (GRFz) from multiple limbs simultaneously during high-speed, over-ground locomotion would enhance our understanding of the locomotor mechanics of cursorial animals. Here, we evaluate the accuracy of predicting peak GRFz from duty factor (the proportion of the stride for which the limb is in contact with the ground). Foot-mounted uniaxial accelerometers, combined with UHF FM telemetry, are shown to be practical and accurate for the field measurement of stride timing variables, including duty factor. Direct comparison with the force plate produces a mean error of 2.3 ms and 3.5 ms for the timing of foot on and foot off, respectively, across all gaits. Predictions of peak GRFz from duty factor show mean errors (with positive values indicating an overestimate) of 0.8+/-0.04 N kg(-1) (13%; N=42; mean +/- S.E.M.) at walk, -0.3+/-0.06 N kg(-1) (3%; N=75) at trot, -2.3+/-0.27 N kg(-1) (16%; N=18) for the non-lead limb at canter and +2.1+/-0.7 N kg(-1) (19%; N=9) for the lead limb at canter. The substantial over- and underestimate seen at canter, in the lead and non-lead limbs, respectively, is attributed to the different functions performed by the two limbs in the asymmetrical gaits. The difference in load experienced by the lead and non-lead limbs decreased with increasing speed. |
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Structure and Motion Lab, The Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, AL9 7TA, UK |
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0022-0949 |
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PMID:15371472 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3658 |
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Author |
Spadavecchia, C.; Arendt-Nielsen, L.; Spadavecchia, L.; Mosing, M.; Auer, U.; van den Hoven, R. |
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Title |
Effects of butorphanol on the withdrawal reflex using threshold, suprathreshold and repeated subthreshold electrical stimuli in conscious horses |
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Journal Article |
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Year |
2007 |
Publication |
Veterinary anaesthesia and analgesia |
Abbreviated Journal |
Vet Anaesth Analg |
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34 |
Issue |
1 |
Pages |
48-58 |
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Keywords |
Analgesics, Opioid/pharmacology; Animals; Butorphanol/*pharmacology; Consciousness; Electric Stimulation; Electromyography; Female; Forelimb/physiology; Horses/*physiology; Male; Pain/veterinary; Pain Threshold/*drug effects; Reflex/*drug effects |
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Abstract |
OBJECTIVE: To assess the effects of a single intravenous dose of butorphanol (0.1 mg kg(-1)) on the nociceptive withdrawal reflex (NWR) using threshold, suprathreshold and repeated subthreshold electrical stimuli in conscious horses. STUDY DESIGN: 'Unblinded', prospective experimental study. ANIMALS: Ten adult horses, five geldings and five mares, mean body mass 517 kg (range 487-569 kg). METHODS: The NWR was elicited using single transcutaneous electrical stimulation of the palmar digital nerve. Repeated stimulations were applied to evoke temporal summation. Surface electromyography was performed to record and quantify the responses of the common digital extensor muscle to stimulation and behavioural reactions were scored. Before butorphanol administration and at fixed time points up to 2 hours after injection, baseline threshold intensities for NWR and temporal summation were defined and single suprathreshold stimulations applied. Friedman repeated-measures analysis of variance on ranks and Wilcoxon signed-rank test were used with the Student-Newman-Keul's method applied post-hoc. The level of significance (alpha) was set at 0.05. RESULTS: Butorphanol did not modify either the thresholds for NWR and temporal summation or the reaction scores, but the difference between suprathreshold and threshold reflex amplitudes was reduced when single stimulation was applied. Upon repeated stimulation after butorphanol administration, a significant decrease in the relative amplitude was calculated for both the 30-80 and the 80-200 millisecond intervals after each stimulus, and for the whole post-stimulation interval in the right thoracic limb. In the left thoracic limb a decrease in the relative amplitude was found only in the 30-80 millisecond epoch. CONCLUSION: Butorphanol at 0.1 mg kg(-1) has no direct action on spinal Adelta nociceptive activity but may have some supraspinal effects that reduce the gain of the nociceptive system. CLINICAL RELEVANCE: Butorphanol has minimal effect on sharp immediate Adelta-mediated pain but may alter spinal processing and decrease the delayed sensations of pain. |
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Anesthesiology Section, Department of Clinical Veterinary Sciences, Vetsuisse Faculty, University of Berne, Berne, Switzerland. claudia.spadavecchia@veths.no |
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1467-2987 |
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PMID:17238962 |
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refbase @ user @ |
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92 |
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