Piglets behavioural responses to surgical castration under inhalation anaesthesia: preliminary results

Surgical castration of male piglets is a common, but stressful and painful practice (Prunier et al, 2006). This study aimed to evaluate piglets behavioural responses to surgical castration under inhalation anaesthesia and pharmacological and non-pharmacological analgesic treatments. 50 commercial-hybrid piglets were allocated to three treatments: Placebo (n=17) (5 ml of water), Glucose (n=16) (5 ml of glucosate at 10%), Meloxicam (n=17) (5 ml of meloxicam 1 mg/kg). Treatments were administered before castration per os. Piglets were castrated under automated isoflurane anaesthesia at 4 days of age. Before and after surgical castration, eye temperature was measured with an infrared camera (Avio Nec G120EX) and behaviour of piglets was video recorded for ten minutes. Videos were evaluated by 2 trained observers (scan sampling every 30 sec), considering explorative behaviour, inactivity, lying and flight reactions. Procedures were approved by Italian Ministry of Health (863/2020-PR). Any time (pre-post procedure) and treatment effects were investigated using analysis of variance (ANOVA). After castration, piglets showed a significant reduction of exploration and flight reactions and a significant increase of both ventral and isolated lying, regardless from the treatment (time p<0.001; treatment p>0.05). Inactivity was not influenced neither from time nor treatment (p>0.05). The eye temperature decreased significantly after castration, but it was not influenced by the treatment (time p<0.01; treatment p>0.05). Piglets castrated under inhalation anaesthesia showed alterations in behaviour and body temperature regardless of treatments; it remains to be investigated whether treatments affected the latency to return to normal behaviour.