This graph shows the changes in plasma cortisol seen after
scoop dehorning of 3 to 4 month old calves with and without local anaesthetic and NSAID
treatment.
DH - dehorn no analgesic
DHLA - dehorn with local anaesthetic
DHLK - dehorn with local anaesthetic and NSAID
sham - handled control calves
Use of both a NSAID and local anaesthetic is required to
remove most of the cortisol response, and by inference the pain, resulting from
scoop dehorning of calves. Cauterisation of the wound or use of a hot dehorning
iron has a similar effect as the NSAID on the cortisol response to dehorning
(Petrie et al 1996;
Sylvester et al 1998).
Scoop dehorning produces peak plasma cortisol values (135nmol/l above
pre-treatment values) within 30 min of treatment. Raised values between 60 and
20 nmol/l occur for up to 7 hours after dehorning. Local anaesthetic
treatment before dehorning abolishes the immediate behavioural response to
dehorning (reduced struggling) but only delays the cortisol response (peak 130
nmol/l above pre-treatment values) until 5 to 8 hours after dehorning. If
an anti-inflammatory drug (ketoprofen) is also given before dehorning, at about the same time as
the local anaesthetic, then the delayed marked cortisol peak response seen with
local anaesthetic use is reduced to a maximum of 40 nmol/l. The cortisol
response has returned to pre-treatment values by 12 hours after all treatments.
Using a heated dehorning iron or cauterising the wound after scoop dehorning
with local anaesthetic, has the same effect on the plasma cortisol response as
using an anti-inflammatory drug (Sylvester
et al 1998).
