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Surgical castration in male piglets is painful and methods that reduce this pain are requested. This study evaluated the effect of local anaesthesia and analgesia on vocal, physiological and behavioural responses during and after castration. A second purpose was to evaluate if herdsmen can effectively administer local anaesthesia by intratesticular injection.
The study was conducted between October 2009 and February 2010 in five piglet-producing herds in the south-central part of Sweden. A total of 557 male piglets from 141 litters were randomly assigned to one of four treatments: castration without local anaesthesia or analgesia (C, controls), analgesia (M, meloxicam), local anaesthesia (L, lidocaine), or both local anaesthesia and analgesia (LM). Castration was performed on 1-7 days old piglets and the majority of the piglets were 3-4 days old when castrated. Before the study started, the herdsmen received instructions from a veterinarian on how to inject local anaesthesia and analgesia. Lidocaine (L, LM) was injected at least three minutes before castration and meloxicam (M, LM) was injected after castration. During castration, vocalisation was measured and resistance movements judged. Behaviour observations were carried out on the castration day and the following day. The day after castration, castration wounds were ranked, ear and skin temperature was measured, and blood samples were collected for analysis of acute phase protein Serum Amyloid A concentration (SAA). Piglets were weighed on the castration day and at three weeks of age. Sickness treatments and mortality were recorded until three weeks of age.
Piglets castrated with lidocaine produced calls with lower intensity (p < 0.001) and less resistance movements (p < 0.001) during castration. Piglets that were given meloxicam displayed less pain-related behaviour (huddled up, spasms, rump-scratching, stiffness and prostrated) on both the castration day (p = 0.06, n.s.) and the following day (p = 0.02). Controls had less swollen wounds compared to piglets assigned to treatments M, L and LM (p < 0.001). The proportion of piglets with high SAA concentration (over threshold values 200, 400 mg/l) was higher (p = 0.005; p = 0.05) for C L compared to M LM. Ear temperature was higher (p < 0.01) for controls compared to L and LM. There were no significant treatment effects for skin temperature, weight gain, sickness treatments or mortality.
The study concludes that lidocaine reduced pain during castration and that meloxicam reduced pain after castration. The study also concludes that the herdsmen were able to administer local anaesthesia effectively.
M. Hansson, N. Lundeheim, G. Nyman and G. Johansson. Effect of local anaesthesia and/or analgesia on pain responses induced by piglet castration. Acta Veterinaria Scandinavica 2011, 53:34 doi:10.1186/1751-0147-53-34
