Guesgen, M. J., Beausoleil, N. J., Minot, E. O. et al. 2014. Social context and other factors influence the behavioural expression of pain by lambs. Applied Animal Behavioural Science 159, 41-49.
There is evidence that the presence of a conspecific can alter the experience of pain in humans and other animals. This ‘social buffering’ may be mediated by factors such as relatedness and familiarity. This study investigates whether and how the social context affects the behavioural response of lambs to painful tail-docking. Specifically, we investigated whether the presence of a lamb that is familiar, related or neither, and previous experience of the test environment affected pain expression. Forty-four lambs were reared to allow testing in one of three social conditions: Familiar Related (FR, twins), Familiar Unrelated (FU) or Unfamiliar Unrelated (UU). Each lamb was exposed to the test environment twice over two rounds, once as the actor (i.e. tail-docked) and once as the observer (not tail-docked). The pain-related behaviour of the actor lamb, as well as where it was looking was recorded before and after tail-docking. As expected, all docked lambs showed an increase in the frequency of active behaviours previously associated with docking pain, an increase in the time spent in abnormal postures and decrease in time spent in normal postures. However, lambs tested with a familiar, related partner (twin) showed a smaller increase in rolling than the other groups (mean ranks of change ± SE: FR 16.43 ± 3.08, FU 26.27 ± 2.59, UU 26.00 ± 3.19). In addition, lambs who had previously experienced the test environment showed overall less activity and a smaller increase in active behaviours after docking than those docked on their first exposure (e.g. round 1 and 2 mean ranks ± SE: jump 49.37 ± 2.94, 40.42 ± 3.02; looking at own tail 49.59 ± 2.51, 39.74 ± 2.57; round 1 and 2 mean ranks of change ± SE: headshake 28.24 ± 2.35, 16.73 ± 2.48; abnormal upright 29.04 ± 2.45, 15.80 ± 2.58). This is the first study to demonstrate that the occurrence of social buffering on lamb pain behaviour depends on the relationship between the actor and observer and on previous experience of the test environment.