title: Do psychological and physiological stressors alter the acute pain response to castration and tail docking in lambs?
abstract: OBJECTIVE
  To investigate whether events that may be stressful to young lambs, including simulated infection or social isolation, modulate pain experienced by lambs following castration and tail docking (C/D).
  
  
  METHODS
  Randomised, controlled, prospective study.
  
  
  METHODS
  Fifty male lambs born to 46 second-parity Mule ewes.
  
  
  METHODS
  Lambs were allocated randomly to one of four groups, experiencing either a potential stressor or handling on day 2 after birth, followed by C/D or handling only on day 3. Quantitative sensory testing (QST) data [mechanical nociceptive thresholds (MNT), Semmes Weinstein filaments (SW), response to cold] and serum cortisol concentration were measured at time points after application of treatments to lambs on days 2 and 3 after birth. The treatment groups were LPS, injection of bacterial lipopolysaccharide IV on day 2, C/D on day 3; ISOL, isolation from the dam for 10 minutes on day 2, C/D on day 3; CAST, handling only on day 2, C/D on day 3; CONT, handled only on days 2 and 3.
  
  
  RESULTS
  Castration and tail docking caused transient hypoalgesia as measured by MNT and SW. Simulated infection and isolation caused hyperalgesia 3 hours after application, indicated by a reduction in MNT, however they did not alter the pain response to C/D compared to lambs in the CAST group. Injection of LPS and C/D caused increased serum cortisol concentration. The magnitude of the cortisol response to C/D was not altered by prior exposure to either LPS or isolation.
  
  
  CONCLUSIONS
  LPS and isolation did not modulate the response to C/D but did cause hyperalgesia. This highlights the importance of flock health management and husbandry techniques to reduce the incidence of either systemic infection or psychological stressors in young lambs.
authors.affiliation: Department of Clinical Veterinary Science, University of Bristol, Langford, North Somerset, UK.
authors.forename: Corinna
authors.initials: C
authors.lastname: Clark
authors.forename: Mike
authors.initials: M
authors.lastname: Mendl
authors.forename: Jennifer
authors.initials: J
authors.lastname: Jamieson
authors.forename: Ashleigh
authors.initials: A
authors.lastname: Arnone
authors.forename: Avril
authors.initials: A
authors.lastname: Waterman-Pearson
authors.forename: Joanna
authors.initials: J
authors.lastname: Murrell
mesh_terms: D000818:Animals; D006930:Hyperalgesia / Q000503:physiopathology / Q000662:veterinary; D008297:Male; D009919:Orchiectomy / Q000379:methods / Q000662:veterinary*; D010146:Pain / Q000503:physiopathology / Q000523:psychology / Q000662:veterinary*; D010147:Pain Measurement / Q000662:veterinary; D012756:Sheep / Q000502:physiology / Q000523:psychology / Q000601:surgery*; D013312:Stress, Physiological / Q000502:physiology*; D013623:Tail / Q000601:surgery*