Sedative and antinociceptive effects of romifidine and xylazine in Thoroughbred mares

Abstract

The sedative and antinociceptive effects of romifidine (0.1mg/kg) and of xylazine (1.0mg/kg) on Thoroughbred mares were studied. Sedation was evaluated by quantifying spontaneous locomotor activity (SLA) and head height (HH) in animals placed in automated individual behaviour stalls. Antinociception was determined utilizing a heat irradiation lamp recording the latency time for the hoof withdrawal reflex (HWRL) and the latency time for the skin twitch reflex (STRL) in a randomised block design with 10 replicates. Comparison of the sedative effects of romifidine and of xylazine on SLA showed a faster effect for xylazine. Regarding the sedative effect of the substances based on HH, romifidine caused a longer-lasting effect. Romifidine caused an increase in HWRL and STRL, and xylazine, an agent known for its analgesic effect, did not have an antinociceptive effect based on STRL result. The antinociceptive effect of romifidine was more pronounced than the xylazine effect.Keywords: horse, romifidine, xylazine, antinociception, sedation Palavras-chave: eqüino romifidina, xilazina, antinocicepção, sedação RESUMO Compararam-se os efeitos sedativos e antinociceptivos da romifidina (0,1mg/kg) e da xilazina (1,0mg/kg) em éguas da raça Puro Sangue Inglês. A sedação foi quantificada por meio da atividade locomotora espontânea (ALE) e altura da cabeça (AC) em baias individuais automatizadas para o estudo do

Comparação dos efeitos da romifidina e de uma emulsão de amitraz na sedação e na atividade locomotora espontânea de eqüinos

“…In horses, romifidine at doses varying from 0.4 to 1 mg/kg induces dose-dependent sedation. 9,10,11 Amitraz showed central effects of alpha-2 adrenoceptor agonist, inducing similar ataxia, intestinal stasis, behavioral, cardiovascular, muscular and diuretic effects. 12,13,14,15,16,17 These effects could provide an indication for the use of amitraz for sedation practices in veterinary medicine, and this might be particularly appealing in horses because of its low price and its potential analgesic and muscle relaxing effects.…”