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dc.contributor.authorRennie, Anita Ellenen
dc.date.accessioned2018-05-14T10:15:38Z
dc.date.available2018-05-14T10:15:38Z
dc.date.issued2005en
dc.identifier.urihttp://hdl.handle.net/1842/29961
dc.description.abstracten
dc.description.abstractLambs castrated and tail-docked (c+td) by tight rubber ring experience severe acute pain lasting up to 3 hours. The use of behaviour to assess the severity of this pain has been validated. Within 5-7 days of application of rubber rings to the neck of the scrotum and the tail, chronic inflammatory lesions form at the sites of the rings. These lesions take 6-7 weeks to heal and can become severely infected. The presence of these chronic inflammatory lesions has been associated with the infrequent expression of the behaviours used to assess acute pain from c+td. It has been proposed that the occurrence of these behaviours is indicative of chronic inflammatory pain, but the use of behaviour has not been validated for the assessment of this pain. The aim of this thesis was to test the following hypotheses:en
dc.description.abstract1. Lambs undergoing castration and tail-docking by tight rubber ring experience chronic inflammatory pain for up to six weeks, in association with chronically inflamed lesions; 2. The chronic inflammatory pain experienced by lambs is sufficient to induce changes in their behaviour; 3. Quantification of these behavioural changes constitutes a valid measure of the chronic inflammatory pain experienced by rubber ring castrated and taildocked lambs.en
dc.description.abstractTwo methods were used to determine the presence of chronic inflammatory pain. The analgesic self-administration paradigm has been used as a means of investigating the experience of chronic inflammatory pain in rats suffering from adjuvant induced arthritis (AA). Similarly, in the studies reported in this thesis, the ability of RR c+td lambs to self-administer a NSAID was used to determine the presence of chronic inflammatory pain. Up-regulation of the synthesis of AVP and reduction in the synthesis of CRH in the parvocellular portion of the hypothalamic paraventricular nucleus (pPVN) has also been detected in rats with AA. Using in situ hybridisation histochemistry, evidence of such changes in the control of the HPA axis were sought in the present studies, to confirm the presence of chronic inflammatory pain in RR c+td lambs. Throughout the self-administration and neurohistochemical studies, the severity of chronic inflammatory lesions and the expression of potential 'pain' behaviours were recorded to determine the significance of these measures with respect to chronic inflammatory pain. Evidence of a relationship between lesion severity and the magnitude of the change in behaviour was also sought.en
dc.description.abstractThe studies reported in this thesis further support the relationship between assessments of lesion severity and quantified changes in behaviour that have been associated with acute pain. The validity of the use of subtle changes in posture and changes in feeding motivation to quantify chronic inflammatory pain was supported as the consumption of analgesic creep feed resulted in elimination of the abnormal expression of these behaviours. Some evidence that c+td lambs select more analgesic feed was also present in these studies, although the responses were not reliable within and between individuals. No evidence was found of changes in the expression of hormones in the HPA axis that are characteristic of chronic inflammatory pain in rats.en
dc.description.abstractDefinitive evidence of the experience of chronic inflammatory pain was not provided by either the self-administration paradigm or the neurohistochemical studies. The use of changes in behaviour to assess chronic inflammatory pain must still be validated, but it is proposed that the incidence of abnormal lying and changes in feeding motivation are reliably associated with the severity of chronic inflammatory pain. It is possible that the unchanged expression of AVP and CRH mRNA in the pPVN is a reflection of differences in the mechanisms of control of the chronically activated HPA axis in the rat and the sheep. It is also considered likely that lambs were unable to learn about the pain relieving properties of the analgesic creep feed, because the study did not provide the appropriate opportunity to learn the association. It is suggested that lambs may be able to control their experience of pain by adopting changes in posture and through activation of local endogenous analgesic mechanisms, thus avoiding the need for activation of the pPVN or other central mechanisms and precluding the need for the lamb to select an analgesic treatment. The evidence supports the assertion that chronic inflammatory lesions from RR c+td are painful, a conclusion that can be used to further oppose of the use of RRs commercially. The potential use of RR c+td lesions as a model of chronic inflammatory pain was demonstrated.en
dc.publisherThe University of Edinburghen
dc.relation.ispartofAnnexe Thesis Digitisation Project 2018 Block 18en
dc.relation.isreferencedbyAlready catalogueden
dc.titleStudies of chronic inflammatory pain in lambs after rubber ring castration and tail-docking: self-administration of analgesic and neurohistochemistry to validate behavioural assessmenten
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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