title: Effects of an oral dose of acetyl salicylate at tail docking on the behaviour of lambs aged three to six weeks.
abstract: To investigate a practical method of providing analgesia for docking of lambs' tails, the effectiveness of an oral dose of aspirin (acetyl salicylate) in reducing discomfort behaviour immediately following application of elastrator rings, was evaluated. The study involved a pilot trial and an experiment, both using Romney crossbred lambs aged 3-6 weeks accompanied by their mothers in a group pen, with behaviour recorded on videotape. In the pilot trial, lambs were manually restrained, an elastrator ring was applied, then lambs were given either an oral dose (26mg/kg) of aspirin dissolved in water (Treatment RA, n=5 lambs) or an oral dose of water (Treatment R, n=4 lambs), and released. RA lambs changed posture between sternal recumbency and standing less frequently than R lambs, significantly so from 10 to 20min post-treatment (11 times for RA, compared with 28% (S.E.D. 6.6%) for R lambs). In the experiment, 56 lambs were given one of two docking treatments (either RA: application of an elastrator ring plus the same aspirin treatment as in the pilot trial, or R: application of the ring plus water), or one of two control treatments (CA: restraint plus aspirin; or C: restraint plus water). During the hour after treatment, docking was associated with differences in over three quarters of 52 postures and activities used to describe behaviour (P<0.05), and marked changes over time in the postures/activities affected were observed. Differences were evident within 5min and some were still apparent at 60min post-treatment. When postures and activities were designated as 'normal' or 'abnormal' (typical of docked lambs), over the total hours of observation the mean frequency of abnormal postures was 3.5% for control lambs and 22.6% (S.E.D. 1.64%) for docked lambs, and the mean frequency of abnormal activities was 5.2% for control lambs and 19.3% (S.E.D. 1.40%) for docked lambs. Provision of aspirin to docked lambs was associated with similar levels to those seen in control lambs for two activities but was also associated with increased levels of some activities/postures (P<0.05). These effects were minor compared with the effects of docking and there was no indication of effective analgesia. Thus, when elastrator tail docking rings were applied, behavioural effects indicative of pain were observed immediately and did not subside fully within 1h. Despite indications in the pilot trial of an analgesic effect of aspirin, further experimentation did not substantiate this effect.
authors.affiliation: AgResearch, Invermay Agricultural Centre, Private Bag 50034, Mosgiel, New Zealand
authors.forename: J C.
authors.initials: JC
authors.lastname: Pollard
authors.forename: V
authors.lastname: Roos
authors.forename: R P.
authors.initials: RP
authors.lastname: Littlejohn