The influence of various confounding factors on mechanical nociceptive thresholds in the donkey

Nicola J Grint, Thierry Beths, Kathy Yvorchuk, Polly M Taylor, Mike Dixon, Helen R Whay, Joanna C Murrell

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

22 Citations (Scopus)


OBJECTIVE: To evaluate a mechanical nociceptive threshold (MNT) testing device in the donkey, and to investigate the influence of potential confounders on MNTs generated.

STUDY DESIGN: Prospective, randomised.

ANIMALS: Sixteen castrated male donkeys aged 4-9 years, weighing 105-170 kg.

METHODS: Mechanical nociceptive thresholds were measured using an actuator with three pins placed on the dorsal aspect of the distal limb, connected to a force meter. The pins (surface area 15 mm(2) ) were extruded onto the limb by pressurising an air-filled syringe, until the MNT force (when foot-lift was observed) or 25 N (cut-off force) was reached. Effect on MNT of presence of a companion donkey, the limb tested, rate of application of force, testing location, level of distraction, ambient temperature and hair cover at the test site was evaluated. Long and short-term repeatability of MNT was assessed. Data were analysed using general linear models and Mann-Whitney U tests, p < 0.05 was considered significant.

RESULTS: Increasing the rate of force application significantly increased the mean ± SD MNT from 9.2 ± 2.0 N when applied at 0.4 N sec(-1) to 10.6 ± 2.1 N when applied at 1.2 N sec(-1) (p = 0.001). No other factors significantly influenced MNT. Mean MNT remained stable over a 3 week period, however MNTs were significantly (p = 0.006) higher (12.8 ± 3.0 N cf 10.3 ± 1.9 N) after a 12 month interval.

CONCLUSIONS AND CLINICAL RELEVANCE: When designing studies measuring MNT in donkeys, rate of application of force must be standardised. Donkeys' MNTs have good short-term stability suggesting this technique is appropriate for short-term analgesiometry studies; however variability of MNTs over the long-term is greater.

Original languageEnglish
Pages (from-to)421-9
Number of pages9
JournalVeterinary Anaesthesia and Analgesia
Issue number4
Publication statusPublished - Jul 2014

Bibliographical note

© 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.


  • Animals
  • Equidae
  • Male
  • Pain Measurement
  • Pain Threshold
  • Pressure
  • Time Factors


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