Behavioural, endocrine and cardiac responses in young calves undergoing dehorning without and with use of sedation and analgesia.

Behaviour, plasma cortisol and heart rate were measured in 4-6-week-old calves during and after dehorning with and without the use of sedation and analgesia. Six groups of eight Friesian male and female calves were studied; four groups were dehorned using an electrical cauterizing dehorner, heated to approximately 600 degrees C. In group 1, a cornual nerve block was performed and the animals were sham-dehorned using a cold dehorner. Group 2 was treated similarly but dehorned with the heated dehorner. Group 3 received a mixture of xylazine and butorphanol intramuscularly, and were hot dehorned 20 min after the injection. Group 4 received the same sedatives-analgesics as group 3, and after 5 min also had a cornual nerve block, followed by hot dehorning 15 min later. Group 5 was hot dehorned without any form of sedation or analgesia. A sixth group of calves without any treatment or handling was used as controls for the behavioural observations. Head and leg movements during dehorning were significantly reduced when the cornual nerve was blocked. During the 4 h after dehorning, the behaviour of calves having a cornual block continued to differ from those in group 5. The cornual block prevented short-term increases in plasma cortisol concentrations and the long-term increases in heart rate seen in group 5. It was concluded that routine field use of local analgesia using a cornual nerve block improved the welfare of young calves subjected to dehorning with a hot iron.