[Ethological, physiological and histological aspects of pain and stress in cattle when being dehorned]

The behaviour of 101 calves was evaluated during (n = 73) and after (n = 28) thermical dehorning without anaesthesia. Cortisol in saliva (n = 68) was measured in 68 calves. A simulation of dehorning was carried out as a control in most of the animals. The area around the horn bud was examined histologically in 20 calves of different ages (newborn until 3-4 months old). Additionally, the influence of dehorning cows with a wire-saw under anaesthesia on behaviour (n = 16), cortisol in saliva (n = 23), and the milk yield was examined. Independent of the calves' age, the horn bud and the surrounding hairy area were well innervated. For all calves dehorning without anaesthesia was a painful experience. During dehorning calves showed distinct pain and defense reactions. Most reactions were observed more often when the calves were dehorned as when dehorning was simulated. The cortisol in saliva was significantly increased after dehorning. In summary, we have to conclude that calves have a well developed nociceptive system from birth on. Therefore calves should only be dehorned using anaesthesia. Despite the anaesthesia, dehorning was stressful for the cows, as measured by a significant increase of cortisol in saliva. Moreover, cows showed pain reactions when the effects of the anaesthesia diminished. Dehorning had only a short effect on the milk yield of the cows.