Abstract
BackgroundSurgical 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 anaesthesia.MethodsFour male piglets in each of 141 litters in five herds 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). 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.ResultsPiglets 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.ConclusionsThe 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.
Highlights
Surgical castration in male piglets is painful and methods that reduce this pain are requested
The following day, treatment C and L were relatively comparable because the piglets were not given meloxicam, while the piglets in treatments M and LM had been treated with meloxicam
Vocalisation and resistance movements during surgical castration In agreement with other studies on piglet vocalisation during castration [3,4], the present study shows that piglets castrated with lidocaine produced calls with a lower intensity than piglets castrated without lidocaine
Summary
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. Each year approximately 1.5 million male piglets are surgically castrated in Sweden. The castration is mainly performed to eliminate boar taint in the meat, and to prevent aggressive and sexual behaviour of male pigs. Castration is performed within the piglet’s first week of life and is traditionally carried out without anaesthesia and analgesia. It is widely accepted that piglets may react to pain in three ways: trough vocalisation, physiologically, and behaviourally [3]. The greatest amount of highfrequency calls are produced when the piglet’s spermatic cords are pulled and severed, and is identified as the most painful moment during castration [8]
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