Does local anaesthetic reduce pain in rubber ring castration of neonatal lambs?
In the UK there is currently no legal requirement for local anaesthestic (LA) to be used when castrating lambs less than one week old with rubber rings. The papers reviewed here covered a 30 year period of research into pain reduction for castration in lambs. Markers of pain used for outcomes were mostly plasma cortisol (Mellor & Murray, 1989) and behavioural expressions and postures which have been demonstrated to be sensitive markers of pain associated with castration in lambs (Mellor & Murray, 1989; Molony et al., 1993; and Molony et al., 2002). A method of assessing acute pain in lambs has been validated by Molony et al. (2002) and these observations formed the basis for behavioural measurements in many of the papers reviewed. Power calculations for sample size were not included in any of the papers and confidence intervals were rarely reported in the results.