The influence of injection anaesthesia with ketamine/azaperone (Ursotamin®, 25mg/kg; Stresnil®, 2mg/kg) and analgesia (Metacam®, 0.4mg/kg) on the behaviour of 5-7 day old piglets after castration was studied (anaesthesia + analgesia: Comb[n= 29], analgesia: Met n= 24], control: Cont [n= 29]). To protect anaesthetised piglets from being crushed, all treatment groups were separated from sow and female siblings for 3 h following castration. The aim of this study was to test if this separation would affect suckling order stability (SOS) and behaviour after reunion. The highest proportion of piglets changing their preferred teat position (TP) in a 3 h period after reunion occurred in the Combtreatment (27.5%), though not statistically significant (Met: 16%; Cont: 17.2%). The change to a lower ranked TP almost reached significance (logistic ANOVA, ?2=5.3, p=0.07) with none of the Metpiglets changing to a lower TP (Comb: 10.3%, Cont: 13.8%), indicating that they might have a better chance of defending their teat. A higher number of teats used by Comb piglets after separation (Wilcoxon test, p=0.004) suggests a significant decrease in SOS in this treatment (Met: p=0.054; Cont: p=0.068). This instability could lead to a reduced milk intake due to fighting over TP, indicating a certain degree of post- surgery stress. Considerable treatment effects appeared in the suckling duration (ANOVA, F=13.3, df=2, p<0.001), with an increase in Met piglets (+68.9±16.5%), but a decrease in Comb animals (-27.6±11%; Cont: +5.9±8.3%). Taken together, the results suggest that Met analgesia has an effect on suckling behaviour of piglets, perhaps due to less post-castration pain. This advantage is not apparent for animals receiving additional anaesthesia, probably because of impaired coordination, which seems to persist a minimum of six hours after castration. Thus, post-castration behaviour must be taken into account when evaluating alternative castration methods.