MacRae, A. M., Makowska, I. J., Fraser, D. 2018. Initial evaluation of facial expressions and behaviours of harbour seal pups (Phoca vitulina) in response to tagging and microchipping. Applied Animal Behaviour Science 205, 167-174.
There are no proven species-specific indicators of pain in harbour seals (Phoca vitulina). The analysis of facial expressions has proven to be a repeatable, accurate and valid method of identifying pain in multiple species, but facial expressions have not been examined in any species of pinniped. This study investigated whether harbour seals’ facial expressions and other behaviours changed immediately after a potentially painful procedure. Forty-seven pups (healthy, >60 d old) at a rehabilitation facility were video-recorded during routine procedures of flipper tagging and microchipping, which are normally done without analgesia. Eight pups were used to generate an ethogram of the facial and behavioural changes seen, 19 pups to compare the behaviours before and after the procedures (Experiment 1), 10 pups in a cross-over experiment comparing responses to real and sham procedures (Experiment 2), and 10 pups to pilot-test a possible analgesic (Experiment 3). For each seal, two observers (Experiment 1) and one observer (Experiments 2 and 3), blind to treatment, watched 90-s video clips recorded just before and just after the procedures. The observers, one experienced with the species and the other not, also made a subjective judgement of whether pain was present or absent for each clip in Experiment 1. In all three experiments, orbital tightening increased from before to after tagging and microchipping (p < 0.0001), whereas the behaviours of looking around (p < 0.01) and struggling (p < 0.05) decreased. Blinking (p < 0.05) decreased in Experiments 1 and 2 while trembling (p < 0.01) decreased only in Experiment 1. Inter-observer reliability ranged from r = 0.82 to 0.92 for these five types of behaviour. In Experiment 2, sham treatment produced no similar changes. In Experiment 3, the procedures produced similar changes likely because the single analgesic/dosage tested was ineffective. For both observers, the subjective scoring of presence or absence of pain corresponded closely to whether or not the procedures had been performed (95% correspondence for experienced and 89% for inexperienced). These results show promise for facial expressions and other behaviours to be used to assess potentially painful procedures in seals.