Effect of caustic paste disbudding, using local anaesthesia with and without analgesia, on behaviour and cortisol of calves

We looked at the effects of local anaesthesia with or without a non-steroidal-anti-inflammatory analgesic drug (flunixin-meglumine) on behaviour and plasma cortisol after caustic paste disbudding of 1-month-old calves: at 15 min, 1, 3, 6 and 24 h (Experiment 1; n = 32); at 10, 30 and 50 min (Experiment 2; n = 35); and after local anaesthesia effect subsided (90–180 min) (Experiment 3; n = 16).In Experiment 1, cortisol was higher at 1 h in paste-disbudded calves than in all other groups. Paste-disbudded and paste-disbudded plus local anaesthesia calves showed higher cortisol at 1 h compared with baseline values. At 15 min paste-disbudded calves showed a higher incidence of pain-related behaviours than all other groups and those with anaesthetic or anaesthetic plus analgesia showed more pain-related behaviours than controls. At 1 and 3 h both paste-disbudded and paste-disbudded plus anaesthetic calves showed more pain behaviours than controls and those with analgesic.In Experiment 2, paste-disbudded calves showed higher cortisol than all other groups at 30 and 50 min. No difference in cortisol was found between anaesthetic, anaesthetic plus analgesia and sham-disbudded calves. The incidence of pain-related behaviours was greater in paste-disbudded calves than in all other groups at all times. Calves disbudded with anaesthetic or with anaesthetic and analgesic showed more pain-related behaviours than sham-disbudded animals during the first 10 min post-procedure.In Experiment 3, paste-disbudded only calves had higher cortisol at 90 min and the anaesthetic-only group had higher cortisol at 180 min, when compared with control animals. Paste-disbudded calves showed more pain-related behaviours at 90, 120 and 150 min, and the anaesthetic-only disbudded calves at 180 min, when compared with sham-disbudded calves. In Experiment 1 and Experiment 3, several disbudded animals showed an “inert-lying” posture and this state may have reduced the display of the other more active behaviours.The evidence indicates that caustic paste disbudding causes distress for at least 3 h and that local anaesthesia is efficient in controlling pain for the first hour but discomfort returns after the nerve blocking subsides. Overall, only local anaesthesia + NSAID provided effective reduction in pain as assessed by this method. Inert lying is a sign of distress in young calves after caustic paste disbudding.