COMPARISON OF SEDATIVE AND CARDIORESPIRATORY EFFECTS OF MEDETOMIDINE AND MEDETOMIDINE-BUTORPHANOL COMBINATION IN DOGS

Objective-Sedative, cardiorespiratory, and analgesic effects of intram uscular administration of medetomidine (40 mu g/kg of body weight)-gly copyrrolate (0.01 mg/kg) and medetomidine (10 mu g/kg)-butorphanol (0. 2 mg/kg)-glycopyrrolate (0.01 mg/kg) combinations were compared. Addit ional evaluations were done on reversal of medetomidine, using atipame zole (200 mu g/kg, IV), after 90 minutes of medetomidine-induced sedat ion. Design-Crossover study, with each dog receiving each drug combina tion at 1-week intervals. Animals-Six 2-year-old English hound-type do gs. Procedure-Arterial blood pressure, EGG, respiratory rate, tidal vo lume, minute volume, arterial blood gas tensions, and serum biochemica l variables were measured before, during, and after sedation. Analgesi a was evaluated by needle prick on the skin and tail clamp. Results-He art rate decreased significantly from 100 beats/min to < 40 beats/min within 3 minutes of injection of medetomidine and medetomidine and but orphanol (MB). Mean arterial blood pressure in both groups were mainta ined above 100 mm of Hg throughout the recording period. There was no significant difference between medetomidine and MB in respiratory rate , tidal volume, and minute ventilation. Hypoxemia (Pa-O2 < 80 mm of Hg ) was observed at 10 and 20 minutes in 2 dogs given MB. Atipamezole ad ministration in the dogs given medetomidine significantly increased Pa -O2 and returned the values to baseline. Needle prick analgesia durati on was longer in the medetomidine (80 +/- 7.7 minutes) than MB (56.0 /- 19.2 minutes) group. Tail pinch analgesia was variable in both grou ps. Duration of lateral recumbency was longer after medetomidine (90 /- 0 minutes) than MB (73.5 +/- 19.0 minutes). Conclusion-Medetomidine and MB were effective combinations for mildly invasive procedures. Cl inical Relevance-MB induced a shorter period of analgesia and recumben cy than did medetomidine.