A small, silent, low friction, linear actuator for mechanical nociceptive testing in veterinary research

Michael Dixon, Polly M Taylor, Louisa S Slingsby, M Hoffmann, Sabine Kastner, Jo C Murrell

Research output: Contribution to journalArticle (Academic Journal)peer-review

29 Citations (Scopus)
254 Downloads (Pure)

Abstract

Air pressure is commonly used to drive a mechanical stimulus for nociceptive threshold testing. This may be bulky, noisy, non-linear and suffer from friction, hence development of a better system is described. A novel, light (14 g) rolling diaphragm actuator was constructed, which supplied 20 N force via a constant actuation area irrespective of the pressure and position in the stroke. Three round-ended pins, 2.5 mm diameter, mounted in a triangle on the piston, provided the stimulus. Pressure was increased manually using a syringe with the rate of rise of force controlled at 0.8 N/s by warning lights. The pressure/force relationship was calibrated using a static force transducer and mercury column. Data were collected with the actuator attached to the antero-medial radius of 12 cats and four dogs. Mechanical threshold was recorded when the animal withdrew the limb and/or turned towards the actuator. Safety cut-off was 20 N. The pressure/force relationship was linear and independent of the start point in the actuator stroke. Baseline feline thresholds were 10.0 {+/-} 2.5 N (mean {+/-} SD), which increased significantly 30 min after butorphanol administration. Baseline canine thresholds were 5.5 {+/-} 1.4 N and increased significantly between 15 and 45 min after administration of fentanyl or butorphanol. The system overcame the problems of earlier devices and detected an opioid-induced increase in threshold. It has considerable advantages over previous systems for research in analgesia.
Translated title of the contributionA small, silent, low friction, linear actuator for mechanical nociceptive testing in veterinary research
Original languageEnglish
Pages (from-to)247 - 253
Number of pages7
JournalLaboratory Animals
Volume44
Issue number3
DOIs
Publication statusPublished - Jul 2010

Keywords

  • Nociceptive threshold testing, unrestrained, pressure actuator, analgesia, opioid

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