A method for studying cutaneous pain perception and analgesia in horses

Steven G. Kamerling, Timothy J. Weckman, David J. Dequick, Thomas Tobin

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Pain perception and its alteration by analgesic drugs is difficult to measure in the horse. The latency to onset of flexion of a limb in response to a noxious thermal stimulus has been used as a nociceptive end point for analgesic studies in many species. While this method has been employed in the horse, it may be confounded by the spontaneous locomotor activity observed after administration of narcotic analgesics. Consequently, an alternative method of assaying narcotic analgesia that did not involve the equine locomotor apparatus was developed. This report describes the use of the heat-evoked skin-twitch reflex as a reproducible measure of pain threshold and its alteration by the narcotic analgesic fentanyl. This method is compared with the heat-evoked hoof-withdrawal reflex, and the apparatus necessary to elicit both reflexes in the horse is described. Fentanyl, administered at intravenous doses of 0.010, 0.005, and 0.0025 mg kg, produced a dose-related prolongation of the skin-twitch reflex but failed to alter the latency to hoof withdrawal folllowing noxious thermal stimulation. The skintwitch reflex is therefore a more sensitive assay of narcotic analgesia in the horse than is the hoof-withdrawal reflex.

Original languageEnglish
Pages (from-to)267-274
Number of pages8
JournalJournal of Pharmacological Methods
Issue number3
StatePublished - Jun 1985

Bibliographical note

Funding Information:
The mechanical and electronic components of the heat projection lamp were constructed by George Umstead, Jr. and William Cotter at the University of Kentucky, Lexington. Research was supported by a grant from the Kentucky Equine Drug Research Council and the Kentucky State Racing and Kentucky Harness Racing Commissions. This is Kentucky Agricultural Experiment Station Article No. 84-4-127, published with the approval of the Dean and Director, College of Agriculture and Kentucky Agricultural Experiment Station. Publication #IO4 from the Kentucky Equine Drug Research and Testing Programs, Department of Veterinary Science and the Graduate Center for Toxicology, University of Kentucky.


  • Analgesia
  • Fentanyl
  • Horses
  • Pain

ASJC Scopus subject areas

  • Pharmacology


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