Comparison of nociceptive withdrawal reflexes and recruitment curves between the forelimbs and hind limbs in conscious horses.
Abstract: To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. Methods: 20 adult horses. Methods: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold intensity was reached. The EMG signal was analyzed for quantification of the NWR. Behavioral responses accompanying the reflex were scored (scale, 0 to 5). The NWR recruitment curves were determined at 0.9, 1.1, 1.2, and 1.3 times the NWR threshold intensity. Results: The NWR threshold was significantly higher for the hind limb (median value, 6.6 mA; range, 3 to 10 mA) than the forelimb (median, 3 mA; range, 1.7 to 5.5 mA). The NWR of the hind limb had a significantly longer latency (median, 122.8 milliseconds; range, 106 to 172 milliseconds), compared with the forelimb (median, 98 milliseconds; range, 86 to 137 milliseconds), and it was associated with significantly stronger behavioral reactions. Gradual increase of NWR amplitude was evident at increasing stimulation intensities and supported by the behavioral observations. Conclusions: We documented NWRs evoked from the forelimb and hind limb and their recruitment with stimuli of increasing intensity in horses. These results provide a basis for use of NWRs in studies on nociceptive modulation in horses.
Publication Date: 2003-06-28 PubMed ID: 12828255DOI: 10.2460/ajvr.2003.64.700Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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This research studied the withdrawal reflexes triggered by pain stimuli in horses’ forelimbs and hind limbs, and compared the intensity of stimuli required to trigger these reflexes. It found that the hind limbs had higher thresholds and reflex latency than the forelimbs and were accompanied by stronger behavioral reactions.
Research Subject and Methodology
- The research was conducted on 20 adult horses.
- Transcutaneous electrical stimulus was applied to the digital palmar/plantar nerve of the animals’ forelimbs and hind limbs.
- The electrical stimulus consisted of five constant current pulses with a duration of 25 milliseconds each.
- The intensity of the current was gradually increased until the horses showed a reflex response triggered by the pain stimuli (nociceptive withdrawal reflex – NWR).
- Behavioral responses of the animals were scored on a scale of 0 to 5 along with the reflex recordings.
Nociceptive Withdrawal Reflex Analysis
- The electromyographic (EMG) activity triggered by the electrical stimulus was recorded from the common digital extensor and cranial tibial muscles in the horses’ limbs.
- The EMG signal was used to quantify the NWR for the forelimb and hind limb of each horse.
- NWR recruitment curves were determined at different levels of stimulus intensities: 0.9, 1.1, 1.2 and 1.3 times the identified NWR threshold intensity.
Findings and Conclusions
- The study found that the NWR threshold was higher for the hind limb (median value of 6.6 MA, ranging from 3 to 10 MA) compared to the forelimb (median value of 3 MA, ranging from 1.7 to 5.5 MA).
- Moreover, the reflex response was slower (longer latency) in the hind limb compared to the forelimb.
- The hind limb NWR was also associated with stronger behavioural responses.
- With gradual increases in the stimulus intensities, the NWR amplitude also progressively increased, as indicated by both the EMG recordings and behavioural observations.
- These findings suggest that NWRs could be used in further studies examining pain perception and its modulation in horses.
Cite This Article
APA
Spadavecchia C, Arendt-Nielsen L, Andersen OK, Spadavecchia L, Doherr M, Schatzmann U.
(2003).
Comparison of nociceptive withdrawal reflexes and recruitment curves between the forelimbs and hind limbs in conscious horses.
Am J Vet Res, 64(6), 700-707.
https://doi.org/10.2460/ajvr.2003.64.700 Publication
Researcher Affiliations
- Department of Clinical Veterinary Sciences, University of Berne, Switzerland.
MeSH Terms
- Animals
- Consciousness
- Female
- Forelimb / physiology
- Hindlimb / physiology
- Horses / physiology
- Male
- Nociceptors / physiology
- Pain / physiopathology
- Pain / veterinary
- Pain Threshold / physiology
- Recruitment, Neurophysiological / physiology
- Reflex / physiology
Citations
This article has been cited 4 times.- Xu M, Zhang Q, Wang Q, Pan D, Ding M, Ding Y. The Characteristics and Distribution of α2D-, α2B- and α2C-Adrenoceptor Subtypes in Goats.. Animals (Basel) 2022 Mar 7;12(5).
- Mühlemann S, Leandri M, Risberg ÅI, Spadavecchia C. Comparison of Threshold and Tolerance Nociceptive Withdrawal Reflexes in Horses.. Animals (Basel) 2021 Nov 26;11(12).
- Haussler KK. Pressure Algometry for the Detection of Mechanical Nociceptive Thresholds in Horses.. Animals (Basel) 2020 Nov 24;10(12).
- Zarucco L, Driessen B, Scandella M, Cozzi F, Cantile C. Sensory nerve conduction and nociception in the equine lower forelimb during perineural bupivacaine infusion along the palmar nerves.. Can J Vet Res 2010 Oct;74(4):305-13.
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