Sex impacts pain behaviour but not emotional reactivity of lambs following ring tail docking

Danila Marini; Jessica E Monk; Dana L M Campbell; Caroline Lee; Sue Belson; Alison Small

doi:10.7717/peerj.15092

Sex impacts pain behaviour but not emotional reactivity of lambs following ring tail docking

PeerJ. 2023 Mar 28:11:e15092. doi: 10.7717/peerj.15092. eCollection 2023.

Authors

Danila Marini^{1

2}, Jessica E Monk^{1

3}, Dana L M Campbell¹, Caroline Lee¹, Sue Belson¹, Alison Small¹

Affiliations

¹ Agriculture and Food, The Commonwealth Scientific and Industrial Research Organisation, Armidale, New South Wales, Australia.
² Davies Livestock Research Centre, School of Animal and Veterinary Science, The University of Adelaide, Adelaide, South Australia, Australia.
³ School of Environmental and Rural Science, The University of New England, Armidale, New South Wales, Australia.

Abstract

Studies in humans have shown sex differences in response to painful events, however, little is known in relation to sex differences in sheep. Understanding sex differences would enable improved experimental design and interpretation of studies of painful procedures in sheep. To examine sex differences in response to pain, 80 lambs were tested across five cohorts of 16. The lambs were penned in groups containing two male and two female lambs with their respective mothers. Lambs were randomly allocated from within each block to one of four treatment groups; FRing-Female lamb, ring tail docked without analgesia, MRing-Male lamb, ring tail docked without analgesia, FSham-Female lamb, tail manipulated and MSham-Male lamb, tail manipulated. Following treatment, lambs were returned to their pen and were video recorded for 45 mins for behavioural observations of acute pain and posture. An hour after treatment, lambs then underwent an emotional reactivity test that consisted of three phases: Isolation, Novelty and Startle. Following treatment, Ring lambs displayed more abnormal postures (mean = 2.5 ± 0.5) compared to Sham lambs (mean = 0.05 ± 0.4, P = 0.0001). There was an effect of sex on the display of acute pain-related behaviours in lambs that were tail docked (P < 0.001), with female lambs displaying more acute behaviours (mean count = +2.2). This difference in behaviour between sexes was not observed in Sham lambs. There was no effect of sex on display of postures related to pain (P = 0.99). During the Novelty and Startle phase of the emotional reactivity test, Ring lambs tended to (P = 0.084) or did (P = 0.018) show more fear related behaviours, respectively. However, no effect of sex was observed. The results of this study indicate that a pain state may alter the emotional response of lambs to novel objects and potential fearful situations. It was also demonstrated that female lambs display increased sensitivity to the acute pain caused by tail docking compared to males.

Keywords: Acute pain; Affective state; Animal welfare; Attention bias; Sex; Sheep; Startle; Tail docking.

MeSH terms

Acute Pain* / veterinary
Animals
Behavior, Animal / physiology
Female
Humans
Male
Orchiectomy / veterinary
Pain Management
Sheep
Tail / surgery

Grants and funding

The authors received no funding for this work.