A COMPARISON OF THE SEDATIVE EFFECTS OF 3 ALPHA-2-ADRENOCEPTOR AGONISTS (ROMIFIDINE, DETOMIDINE AND XYLAZINE) IN THE HORSE

The sedative effects of a new alpha-2-adrenoceptor agonist, romifidine, were compared with those of xylazine and detomidine. Five horses were treated with two doses of romifidine (40-mu-g/kg body weight and 80-mu-g/kg body weight), two doses of detomidine (10-mu-g/kg body weight and 20-mu-g/kg body weight) and one dose of xylazine (I mg/kg body weight) given by intravenous injection using a Latin-square design. The dose of 80-mu-g/kg romifidine appeared equipotent to 1 mg/kg xylazine and 20-mu-g/kg detomidine, although at these doses both xylazine and detomidine had a shorter action. Detomidine 20-mu-g/kg and xylazine both produced greater lowering of the head and a greater degree of ataxia than romifidine at either dose. Romifidine produced sedation similar to that of the other drug regimes. The effect upon imposed stimuli was similar.