Thomsen, P. T., Hansen, J. H., Herskin, M. S. 2021. Dairy calves show behavioural responses to hot iron disbudding after local anaesthesia with procaine. Veterinary Record 188(4), 270-276.

Background: The efficacy of procaine as anaesthetic for disbudding of calves is largely unknown. Likewise, information about effect of interval from local anaesthesia to disbudding and the size of the hot iron used is missing. Methods: A total of 167 dairy calves were disbudded after cornual nerve block with procaine. Time from administration of anaesthetic to disbudding varied, and calves were disbudded using two different sizes of hot iron. The calves’ behavioural responses to disbudding were recorded based on (1) getting up, (2) kicking, and (3) lifting head. Using logistic regression, the associations between calves showing at least one of these three behaviours and interval from administration of anaesthetic to disbudding and size of the hot iron were evaluated. Results: Overall, 42% of calves showed at least one of the three behaviours, even though they had received a cornual nerve block prior to disbudding. Using the large hot iron was associated with a 2.3 times higher odds of the calf reacting behaviourally compared to the small iron. Interval from administration of anaesthetic to disbudding was not significantly associated with the odds of behavioural responses. Conclusion: Approximately 40% of calves disbudded after cornual nerve block with procaine showed signs of inadequate local anaesthesia. This was especially problematic when hot irons with larger tips were used.