Effect of local anaesthetic combined with wound cauterisation on the cortisol response to dehorning in calves

OBJECTIVE: To reassess whether local anaesthesia before dehorning and wound cauterisation after dehorning eliminates the cortisol response to dehorning. METHODS: A control group was compared with three dehorned groups (dehorned alone, dehorned after local anaesthesia, dehorned after local anaesthesia then cautery of the amputation wounds). The local anaesthetic regimen used produced nerve blockade for about 5 h. Blood samples were taken before and after dehorning and plasma cortisol concentrations were determined. RESULTS: Dehorning caused a marked cortisol response lasting for about 7 h. Local anaesthetic reduced the plasma cortisol concentrations to control values for 5 h, after which they increased for a further 5 h. Subsequently in both groups, cortisol concentrations remained at control values until at least 24 h after treatment. Local anaesthetic combined with wound cautery virtually abolished the cortisol response until at least 24 h after dehorning. CONCLUSION: Combining local anaesthesia with cautery of the amputation wounds substantially reduced the cortisol response until at least 24 h after dehorning.