Quantitative assessment of nociception in horses by use of the nociceptive withdrawal reflex evoked by transcutaneous electrical stimulation

Spadavecchia, Claudia; Spadavecchia, L.; Andersen, Ole Kæseler; Arendt‐Nielsen, Lars; Leandri, Massimo; Schatzmann, U.

doi:10.2460/ajvr.2002.63.1551

Cited by 43 publications

(71 citation statements)

References 44 publications

(56 reference statements)

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“…The nociceptive component (NWR, often defined as RIII in humans) is the one deriving from activation of Ad fibers, with an afferent conduction velocity ranging from 4 to 36 m/s (Gasser and Erlanger 1927). For horses, on the basis of experiences collected in several experiments, the epochs 80 -250 ms or 40 -200 ms after stimulation seem the most suitable to recognize the NWR, depending on the specific experimental settings chosen (Spadavecchia et al 2002, Spadavecchia et al 2003, Risberg et al 2014. Later components, possibly deriving from activation of slow conducting nociceptive C fibers, are difficult to recognize as they are contaminated by supraspinal reactions.…”

Section: Quantifying and Defining The Nwrmentioning

confidence: 99%

“…For the forelimb, the extensor carpi radialis, the common digital extensor, the ulnaris lateralis and the deltoid have been evaluated, while for the hindlimb only the tibialis cranialis was used so far. The EMG recording is performed from 100 ms before to 400 ms after the stimulus onset, resulting in a total recording time of 500 ms (Spadavecchia et al 2002). During the entire experimental session, flexible leads and electrodes have to be secured with adhesive bandages to avoid displacements and to prevent disturbances to the horse.…”

Section: Eliciting and Recording The Nwr In Horsesmentioning

confidence: 99%

“…To be considered an NWR, the reflex component in the epoch of interest has to be at least 3 times the background activity (EMG recorded before stimulus onset) (Spadavecchia et al 2002, Spadavecchia et al 2003 or to have a RMS amplitude of at least 30 µV (Risberg et al 2014). …”

Section: Quantifying and Defining The Nwrmentioning

confidence: 99%

“…Stimuli are delivered via self-adhesive electrodes, as previously described in human experiments (Andersen et al 1995). The electrodes are applied to the clipped and degreased skin over the palmar (Spadavecchia et al 2002) or plantar (Spadavecchia et al 2003) digital nerves, which are purely sensory nerves in horses. They are fixed on their limbs during the entire experimental session, so that the animals cannot relate any external sign to the upcoming stimulus.…”

Section: Eliciting and Recording The Nwr In Horsesmentioning

confidence: 99%

“…Furthermore, all these models merely allow the definition of a single threshold value for each experimental condition, typically measured as the time necessary to obtain a behavioural reaction after stimulation onset. As an alternative, the Nociceptive Withdrawal Reflex (NWR) model has been proposed to investigate the physiology of nociception and to evaluate its modulation by analgesic and anaesthetic drugs in horses (Spadavecchia et al 2002, Spadavecchia et al 2003, Spadavecchia et al 2007, Rohrbach et al 2009). This model not only allows a more reliable definition of the nociceptive threshold through neurophysiological characterization of the elicited response (Spadavecchia et al 2002), but also allows to plot a stimulus-response curve together with the assessment of temporal summation mechanisms (Spadavecchia et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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The model of the Nociceptive Withdrawal Reflex in horses

Spadavecchia¹,

Rohrbach²,

Levionnois³

et al. 2016

PHK

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Summary: In equine pain research, the Nociceptive Withdrawal Reflex (NWR) model has been proposed as an alternative to classical thermal, mechanical and electrical models to investigate the physiology of nociception. This model does not only allow a more reliable definition of the nociceptive threshold through neurophysiological characterization of the elicited response , but also consents plotting a stimulus-response curve as well as the evaluation of temporal summation mechanisms. Aim of this report is to summarize the experience and results obtained using the NWR model in horses over the last 15 years, firstly with the purpose of describing its physiological characteristics and secondly with the aim of evaluating its pharmacological modulation through analgesic and anaesthetic compounds. The NWR can be elicited in horses through electrical transcutaneous stimulation of a peripheral sensory nerve and is recorded through electromyographic electrodes from the muscles involved in the withdrawal reaction. As the non-nociceptive fibres have lower threshold to electrical stimuli than the nociceptive one, it is impossible to differentiate between the two groups on the stimulus side. So, the only guidance to assess the quality of the stimulus and the recruitment of nociceptive afferents should rely on the characteristics of the electromyographic response, most of all on the timing of its various components. A reflex response can be considered to be a true NWR only if it appears within a time epoch compatible with the conduction velocity of the A fibers. Furthermore a clearly recognizable EMG burst in the epoch of interest has to be accompanied by a consistent aversive behavioural reaction, thus allowing the definition of a reliable NWR threshold. Responses to stimulation intensities below and above thresholds can be quantified to draw a stimulus response curve. Furthermore, through repeated stimulation at subthreshold intensities, it is possible to elicit the phenomenon of temporal summation, considered to be the early phase of the wind up phenomenon and of relevant interest to study central integrative mechanisms of pain processing. Alpha-2 agonists, opioids, systemic lidocaine, ketamine and inhalation anaesthetics have been investigated using the NWR model in horses. Drug-specific modulation of NWR threshold, stimulus-response curves and temporal summation are summarized for each tested compound.

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Section: Quantifying and Defining The Nwrmentioning

confidence: 99%

Section: Eliciting and Recording The Nwr In Horsesmentioning

confidence: 99%

Section: Quantifying and Defining The Nwrmentioning

confidence: 99%

Section: Eliciting and Recording The Nwr In Horsesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The model of the Nociceptive Withdrawal Reflex in horses

Spadavecchia¹,

Rohrbach²,

Levionnois³

et al. 2016

PHK

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show abstract

Perioperative Pain Management

Lerche¹,

Muir²

2009

Equine Anesthesia

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Power Transfer to a Human during an Electric Eel’s Shocking Leap

Catania

2017

Current Biology

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Electric eels have been the subject of investigation and curiosity for centuries [1]. They use high voltage to track [2] and control [3] prey, as well as to exhaust prey by causing involuntary fatigue through remote activation of prey muscles [4]. But their most astonishing behavior is the leaping attack, during which eels emerge from the water to directly electrify a threat [5, 6]. This unique defense has reportedly been used against both horses [7] and humans [8]. Yet the dynamics of the circuit that develops when a living animal is contacted and the electrical power transmitted to the target have not been directly investigated. In this study, the electromotive force and circuit resistances that develop during an eel's leaping behavior were determined. Next, the current that passed through a human subject during the attack was measured. The results allowed each variable in the equivalent circuit to be estimated. Findings can be extrapolated to a range of different eel sizes that might be encountered in the wild. Despite the comparatively small size of the eel used in this study, electrical currents in the target peaked at 40-50 mA, greatly exceeding thresholds for nociceptor activation reported for both humans [9] and horses [10, 11]. No subjective sensation of involuntary tetanus was reported, and aversive sensations were restricted to the affected limb. Results suggest that the main purpose of the leaping attack is to strongly deter potential eel predators by briefly causing intense pain. Apparently a strong offense is the eel's best defense.

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Quantitative assessment of nociception in horses by use of the nociceptive withdrawal reflex evoked by transcutaneous electrical stimulation

Abstract: Results of our study indicate that it is possible to record NWR in conscious standing horses, to define a reflex threshold, and to measure reflexes in response to increasing stimulus intensity.

Cited by 43 publications

References 44 publications

The model of the Nociceptive Withdrawal Reflex in horses

The model of the Nociceptive Withdrawal Reflex in horses

Perioperative Pain Management

Power Transfer to a Human during an Electric Eel’s Shocking Leap

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