Do rubber rings coated with lignocaine reduce the pain associated with ring castration of lambs?

•A proof of concept study investigated lignocaine coated rings for castrating lambs.•Responses were lower in lambs with coated rings compared to conventional rings.•Responses were not reduced enough to achieve best practice levels of pain relief.•Diffusion through the skin appeared delayed.•Technique has potential for practical administration of pain relief on-farm. To facilitate the wider use of pain relief on-farm, practical ‘farmer friendly’ methods for administering pain relief are necessary. This proof of concept study evaluated the efficacy of rubber rings coated with local anaesthetic (LA, lignocaine) for providing pain relief in lambs castrated 4 weeks after birth. To eliminate any potential effects of blood sampling on behavioural responses to castration, the study was carried out in two parts, utilising different animals. In the first part of the study, behavioural responses were measured for 60 lambs (n=10 per treatment) randomly allocated to: (1) handling without castration (C), (2) castration with a normal rubber ring (R), (3) castration with a rubber ring coated with LA (RLA), (4) LA injected into the testes and scrotal neck 4min before a normal ring was applied (LADR), (5) LA injected immediately prior to a normal ring being applied (LAIR), and (6) injection of LA without castration (LA). Total time lying and frequencies of pain-related behaviour (abnormal lying, activity, postural changes) were recorded by video during baseline (30min) and 3h post-treatment. In the second part of the study, cortisol responses were measured for 24 lambs (n=8 per treatment) allocated to one of three treatments: C, R or RLA as above. Blood samples were taken via jugular venipuncture at 0, 30, 60, 90 and 120min and analysed for plasma cortisol concentrations. In the first part, total time spent lying (%) was lower (P