Evaluating a novel analgesic strategy for ring castration of ram lambs.
Author(s): Paull DR, Small AH, Lee C, Palladin P, Colditz IG.
Affiliation(s): CSIRO Livestock Industries, Armidale, NSW, Australia. david.paull@csiro.au
Publication date & source: 2012, Vet Anaesth Analg. , 39(5):539-49
OBJECTIVE: To evaluate the analgesic efficacy of the NSAIDs flunixin and
meloxicam administered locally to the scrotum before ring castration.
STUDY DESIGN: Randomised, controlled, prospective study.
ANIMALS: Forty eight single born male Merino lambs.
METHODS: Lambs, aged approximately 4 weeks, were allocated to four groups for
castration. Groups were: sham control; castration + saline; castration +
flunixin; castration + meloxicam. Drugs (5 mL) were administered subcutaneously
around the circumference of the scrotum immediately before castration. Cortisol,
rectal temperature, haematology and plasma haptoglobin were measured before and
up to 48 hours after treatment. Behaviour recorded by video for 12 hours after
treatment was classified as pain avoidance behaviours in the first hour and
postural behaviours in three 4 hour intervals.
RESULTS: Ring castration (saline group) induced a bi-phasic increase in cortisol
with peaks at 90 minutes and 24 hours but no significant changes in haematology,
haptoglobin or rectal temperature. Pain avoidance behaviours were increased and
teat seeking decreased. Normal lying and normal standing postures were decreased
and abnormal ventral lying, statue standing, abnormal standing and total abnormal
postures increased. Flunixin decreased cortisol at 90 minutes (60.3 versus 117.3
nmol L(-1) ) and cortisol AUC (0-6 hours), decreased elevated leg movement (2.5
versus 5.4 events) and sum of pain avoidance behaviours (8.5 versus 16.7 events),
improved time spent in normal ventral lying and decreased abnormal ventral lying
and total abnormal postures compared to saline treated lambs. In a similar
contrast, meloxicam caused non-significant decreases in cortisol at 90 minutes,
cortisol AUC (0-6 hours) and pain avoidance behaviours, and significantly
improved the postural behaviours normal ventral lying (26.7 versus 15.4%) and
normal standing (13.9 versus 7.5%), and reduced abnormal standing and total
abnormal postures. Physiological and behavioural responses associated with ring
castration for both NSAID treatment groups were generally greater than sham
controls.
CONCLUSIONS AND CLINICAL RELEVANCE: Locally administered NSAIDs provided partial
analgesia for ring castration.
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