AEC_15_19_Self medication in lambs

In our previously conducted experiment that looked at the efficacy of three non-steroidal anti-inflammatories (NSAID) we identified flunixin as an effective oral analgesic in sheep. We then added flunixin to pelleted feed allowing lambs that had undergone castration and tail-docking to consume the feed. The results of the experiment indicated that administering flunixin to lambs orally in feed was an effective method of providing pain-relief. This was indicated by reduced inflammation and pain responses in lambs given the feed with flunixin following castration and tail-docking. Provision of flunixin in the feed provides a more practical way to provide pain relief to lambs following painful procedures. This study is the final experiment for a PhD project looking into alternative pain relief options for sheep. Previous studies AEC 14/01, AEC 14/21 and AEC 14/31 have provided information that has assisted in planning the methods of this experiment. In the next step of my PhD this experiment is exploring the potential to train lambs to self-administer the drugs to provide pain relief over a period of several days. The NSAID flunixin is chosen as NSAIDs are a non-addictive and long-acting. If the sheep can learn to self-medicate, their voluntary choice to ingest medications that are non-addictive is a strong indicator that the animal feels unwell and is motivated to alleviate that negative affective state. Thus development of a test procedure to examine the choice of sheep to self-medicate would also provide a valuable indicator of affective state in these animals and help us better understand pain and its impacts in livestock. The model of chronic pain used will be ring castration and tail-docking. Rings are commonly used for castration and tail-docking and are shown to cause an acute pain lasting 4 h (Lester et al. 1996;) as well as causing chronic pain (Mellema et al. 2006; Melches et al. 2007). The objectives of this study are to castrate lambs, and offer them medicated feed in a training period. The lambs will then be tail-docked a week later and offered medicated and non-medicated feed again to see if sheep have a preference, if lambs have learnt to associate the odour they were trained on with flunixin, they should have a preference for it. It is hypothesised that if sheep are no longer in pain after 5 weeks any preference they may have exhibited in the preference test after tail-docking should be gone. During this experiment lambs will be monitored for feed consumption and for pain behaviours.