Analgesic efficacy of a novel topical formulation for tail docking in piglets : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North, New Zealand

The following Figures were removed for copyright reasons: Figures 2.1 (=Herskin et al., 2016 Fig 1), 2.2 (Kehlet et al., 2006 Fig 1), 2.3 (=Di Giminiani et al., 2016 Fig 3), 2.4 (=Theurer et al., 2013 Fig 1), 2.5 (=Prunier et al., 2005 Fig 1B & 3B), 2.6 (=Sutherland et al., 2008 Fig 1) & 2.7 (=Zhang & An, 2007 Fig 1).Tail docking of young piglets is a common management procedure which is carried out on pig farms to prevent tail biting behaviour. In New Zealand, pain relief is not required at the time of the procedure if piglets are less than 7 days old. However, tail docking results in behavioural and physiological pain and stress responses in piglets. A survey of pig husbandry practices was carried out before conducting the experimental procedure. The survey had 15 questions which focused on the occurrence of tail biting, of which only one respondent reported tail biting absence. Most questions were centred on tail biting risk factors coming from housing conformations, use of manipulable substances such as straw and feeding systems. Knowledge of farmers’ strategies concerning risk factors can enable stakeholders to advise farmers on the best ways to minimise tail biting. The objective of this research was to evaluate the analgesic efficacy of a novel topical formulation to reduce pain due to tail docking. This was examined in 108 piglets (9 litters of 12 piglets each), which were docked by a gas cautery iron at approximately 2-3 days of age. The study had 3 treatment groups: pain relief provided before docking, (‘Before’); pain relief provided after docking (‘After’); and the control group which had no pain relief (‘Control’). The 9 litters were randomly allocated, such that each treatment group had 3 litters. The behavioural response to docking was recorded during and after docking. The percentages and means for vocalisations and escape attempts before docking were recorded, and these were lowest in the ‘before’ group (P<.0001). Post docking, treatment had a highly significant effect on walking behaviour (P<0.0002). Piglets in the control group had the highest likelihood of walking after docking, followed by the after and before groups respectively. Lying in contact, which signifies social coherence, was more apparent in the before group, (P<0.0001) followed by the after group and was observed at the lowest frequency in the control group. Conversely, the lying in isolation behaviour was highest in the control group, (P<0.0002), followed by the after group and lastly the before group. Sitting and pain related behaviours had the highest occurrences in control piglets, followed by the after group and lastly the before group. Blood sampling was carried out to conduct inflammatory gene expression studies which suggest the level of pain. The results from the study were unbalanced, therefore inconclusive due to sampling challenges which resulted in limited raw data. Blood samples from piglets that had not received pain relief prior to docking were especially difficult to collect. The blood work sought to analyse which cytokines, pro-inflammatory and anti-inflammatory genes would be upregulated following pain due to tail docking. Pre-emptive application of the topical analgesic formulation resulted in fewer pain related behaviour displays but was the most labour-intensive treatment. Further work is required to develop more practical forms of on-farm pain relief during tail docking