Abstract
Objective
To describe anatomical and methodological factors influencing mechanical nociceptive
thresholds (MNTs) and intra-site variability in healthy sows.
Study design
Prospective, randomized validation.
Animals
Eight pregnant, healthy, mixed-parity sows (176–269 kg).
Methods
Repeated MNT measurements were taken: 1) with a hand-held probe and a limb-mounted
actuator connected to a digital algometer; 2) at nine landmarks on the limbs and tail;
and 3) at 1 and 3 minute intervals. Data were analysed using linear mixed regression
models.
Results
The MNTs (±SEM) of the limbs were lower with the probe (14.7 ± 1.2 N) than with the
actuator (21.3 ± 1.2 N; p < 0.001), in the pelvic versus the thoracic limbs (16.7 ± 1.2 versus 19.2 ± 1.2 N; p < 0.001), and in the lateral versus the dorsal metatarsi and metacarpi (17.6 ± 1.2 versus 18.4 ± 1.2 N; p = 0.002). MNTs were higher in all subsequent measurements compared with the first
(p < 0.001) and in the morning compared with the afternoon (p = 0.04). We found no evidence of MNT differences based on interval between consecutive
measurements (1 versus 3 minutes). Variability was lower in the thoracic limbs [mean back-transformed log10 coefficient of variation (CV) ± SE = 25.5 ± 1.5% versus 30.6 ± 1.5% in the pelvic limbs; p < 0.001], with the actuator (22.7 ± 1.5% versus 33.4 ± 1.5% with the probe; p < 0.001), and on the left (CV = 26.9 ± 1.5% versus 29.3 ± 1.5% on the right; p = 0.01). Tail data (probe only) were analysed separately: mean MNT (± SE) was 11.7
(±1.8); MNT increased in days 3–6 of testing compared with day 1 (p < 0.001). The mean CV (±SE) was 38.9% (±1.1%).
Conclusions and clinical relevance
MNTs and intra-site variability in healthy sows were affected by several factors,
indicating that this methodology requires considerable attention to detail.
Keywords
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Article info
Publication history
Accepted:
June 1,
2015
Received:
August 18,
2014
Identification
Copyright
© 2016 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.
