Application of pain relief for castration
Castration of male lambs may occur either by removing the tip of the scrotum and both testes (surgical castration) or by applying a rubber ring to the neck of the scrotum, with castration occurring via ischaemic necrosis (ring castration). Ring castration is considered to be less stressful than surgical castration and is the preferred method. A recent survey suggests 97% of producers use ring castration in lambs. As castration in male lambs is invariably undertaken in conjunction with tail docking, trials assessing the effects of pain mitigation with castration have occurred together with tail docking studies.
For ring castration, lignocaine appears to provide short-term pain relief, and NumOcaine should decrease short-term pain for less than one hour. Tri-Solfen is not suitable, as there is no wound. NSAIDs have not been shown to decrease behaviour responses (despite decreasing cortisol response), but would be expected to have some effect on pain. A combination of NumOcaine (i.e. ring application using NumNuts) and meloxicam should provide the best pain relief under currently registered products.
For surgical castration, Tri-Solfen has been shown to have beneficial effects at reducing pain behaviours. As with mulesing, a combination of meloxicam and Tri-Solfen should provide the best pain relief.