title: Assessments of thermal antinociceptive effects of butorphanol and human observer effect on quantitative evaluation of analgesia in green iguanas (Iguana iguana).
abstract: OBJECTIVE
  To determine whether butorphanol induces thermal antinociception in green iguanas (Iguana iguana) and assess the human observer effect on quantitative evaluation of butorphanol-induced analgesia.
  
  
  METHODS
  6 juvenile green iguanas.
  
  
  METHODS
  Skin temperature was recorded, and then a direct increasing heat stimulus was applied to the lateral aspect of the tail base of each iguana. Temperature of the stimulus at which the iguana responded (thermal threshold) was measured before and for 8 hours after IM injection of either butorphanol tartrate (1.0 mg/kg) or an equal volume of saline (0.9% NaCl) solution. Six experiments (butorphanol [n = 3] and saline solution [3]) were conducted with the observer in the iguanas' field of vision, and 11 experiments (butorphanol [n = 5] and saline solution [6]) were conducted with the observer hidden from their view. The interval between treatments or tests was ≥ 1 month.
  
  
  RESULTS
  Temperature difference between thermal threshold and skin temperature when iguanas were administered saline solution did not differ from temperature difference when iguanas were administered butorphanol regardless of whether the observer was or was not visible. Temperature difference between thermal threshold and skin temperature was significantly lower when iguanas were tested without the observer in visual range, compared with the findings obtained when iguanas were tested with an observer in view, at multiple times after either treatment.
  
  
  CONCLUSIONS
  Intramuscular administration of 1.0 mg of butorphanol/kg did not induce thermal antinociception in juvenile green iguanas. The visible presence of an observer appeared to influence the results of noxious stimulus testing in this reptile species.
authors.affiliation: Disney's Animal Programs and Environmental Initiatives, 1200 Savannah Cir E, Bay Lake, FL 32830, USA. greg.fleming@disney.com
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Fleming
authors.forename: Sheilah A
authors.initials: SA
authors.lastname: Robertson
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000818:Animals; D002077:Butorphanol / Q000627:therapeutic use*; D006358:Hot Temperature / Q000009:adverse effects; D007076:Iguanas / Q000502:physiology*; D007273:Injections, Intramuscular / Q000662:veterinary; D059226:Nociceptive Pain / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D010147:Pain Measurement / Q000379:methods / Q000662:veterinary*; D011446:Prospective Studies; D016037:Single-Blind Method
chemical_list: D000701:Analgesics, Opioid; D002077:Butorphanol