Behavioral, clinical and antinociceptive effects promoted by pre-emptive epidural injection of morphine, xylazine or clonidine, in horses.

Opioids and α2-agonists have analgesic effect and preventive administration by epidural route can minimize undesirable and clinical effects. So, behavioral, clinical and analgesic effects were evaluated for 24 hours after preventive epidural injection of morphine (0.1mg kg-1), xylazine (0.17mg kg-1) or clonidine (3mg kg-1) in /8 horses subjected to incisional model of inflammatory pain evaluated by von Frey filaments. Behavioral changes and changes in heart rate, respiratory rate, rectal temperature and height of head were minimum and transitory. Cutaneous sensivity in injured skin was similar to complete skin for 24, 8 and 12 hours after preventive epidural injection of morphine, xylazine and clonidine, respectively. Moreover, clinical and behavioral changes were not severe along 24 hours. [ABSTRACT FROM AUTHOR]