Evaluation of detomidine-induced analgesia in horses with chronic hoof pain

HG Owens, SG Kamerling, SR Stanton and ML Keowen

Department of Veterinary Physiology, Pharmacology and Toxicology, School of Veterinary Medicine, Louisiana State University, Baton Rouge, USA.

Detomidine (10, 20 and 40 micrograms/kg i.v.) and saline were administered to eight adult horses with hoof pain and lameness associated with chronic laminitis. Mechanical noxious stimulation was applied to 16 loci over the solar surface of each forefoot by means of an electronic hoof tester to determine chronic pain thresholds. Horses were evaluated before and at 25, 55 and 120 min after treatment for lameness and to determine hoof compression thresholds (HCTs), the percentage of responsive loci and the subjective grade of hoof withdrawal response at each responsive locus. Detomidine produced a dose-dependent increase in HCT and a decrease in the subjective grade of hoof withdrawal response through 55 min after treatment. At 25 and 55 min postdose, the 40 micrograms/kg dose produced maximal elevation of the HCT. The percentage of responsive loci was decreased by detomidine at 25 min in a dose-dependent manner. The lameness grade was decreased by 40 and 20 micrograms/kg of detomidine at 25 min postdose. These data support previous studies demonstrating detomidine-induced analgesia in equine models of acute nociception.

Volume 278, Issue 1, pp. 179-184, 07/01/1996
Copyright © 1996 by American Society for Pharmacology and Experimental Therapeutics