Assessment of acute and chronic pain after different methods of castration of calves

Four groups of Ayrshire calves (n-8 each) were castrated at 1 week of age by either surgery, crushing by a Burdizzo, rubber ring or a combination of the Burdizzo and rubber ring methods. Responses of castrated calves were compared with a control group (n-8) of handled calves. Plasma cortisol was measured in blood samples taken during the first 3 h after castration. Observations of behaviour were made for 3 h immediately after castration, and for 3 h each afternoon for the first 4 days and then on every third day to 48 days after treatment. An assessment of the castration site (lesion score) was made after each observation period and the calves were weighed every twelfth day. Acute changes in behaviour and plasma cortisol were consistent with those reported previously, namely that increases in active behaviours, abnormal postures and plasma cortisol occurred in the first 3 h after castration. The behavioural response to both surgical and Burdizzo castration was characterised by immobile postures. The combined Burdizzo and rubber ring method produced a significant reduction in the activity (count per 3 h period) of two behaviours (foot stamping/kicking (11.9) and easing quarters (13.3)) compared with the use of a rubber ring alone (27 and 23.7, respectively). During the 48 days after rubber ring treatments there was an increase in the calves' concern with the site of castration, indicated by a significantly (P<0.01) increased incidence of licking which was associated with increased abnormal standing, with slow movements of the tail, alternate lifting of the hindlegs and head turning as the integrity of the skin broke down. If these indices are valid, they demonstrate that considerable acute and chronic pain is associated with rubber ring methods of castration of calves and that the chronic pain can last for at least 42 days.