Development of objective criteria of pain in animals.

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 15580286
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Clinical veterinary science
• Research Institution: The University of Tokyo
• Principal Investigator: NISHIMURA Ryohei The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (80172708)
• Co-Investigator(Kenkyū-buntansha): SASAKI Nobuo The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 教授 (60107414) ; KUWAHARA Masayoshi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (30205273) ; OHNO Koichi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (90294660) ; MOCHIZUKI Manabu Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor, 大学院・共生科学技術研究部, 助教授 (90261958)
• Project Period (FY): 2003 – 2005
• Keywords: cortisol / ACTH / pain / nociception / opioid / NSAIDs / blood pressure / heart rate

Research Abstract

First, the relationship between noxious stimulus and neurohormonal responses was evaluated in dogs. The changes in heart rate, blood pressure and plasma ACTH and cortisol levels were recorded during major surgeries. Heart rate and blood pressure did not change significantly during or after major surgical manipulation except for skin incision in many dogs. On the contrary, the plasma ACTH and cortisol levels changed in accordance to the degree of potency of surgical manipulation in most dogs. Cortisol was thought to be more valuable than ACTH because of its less individual differences and easy measurement protocol. In addition, the increase in plasma cortisol level induced by surgical manipulation was significantly suppressed by use of potent analgesics such as morphine or fentanyl.
Second, antinociceptive effect of a non steroidal anti-inflammatory drug (NSAID) was compared with that of opioids by use of cortisol levels during and after surgery. Preemptive administration of NSAID suppressed the increase in plasma cortisol level caused by surgical manipulation and maintained it at similar level to that in dogs given opioids during and after operation. In addition, the changes in post-operative pain score determined by visual analog scale (VAS) were well correlated with the changes in plasma cortisol levels in both groups.
Finally, the effect of high dose of opioid with or without adjunctive drugs on neurohormonal response caused by noxious stimulus was evaluated by use of cortisol level. High dose of fentanyl with ketamine and lidocaine exerted almost complete antinociceptive effects during surgery.
In conclusion, plasma cortisol level is a valuable and objective criteria of pain in dogs.