Abstract
Objective
Sedative, cardiorespiratory, and analgesic effects of intramuscular administration of medetomidine (40 µg/kg of body weight)-glycopyrrolate (0.01 mg/kg) and medetomidine (10 µg/kg)-butorphanol (0.2 mg/kg)-glycopyrrolate (0.01 mg/kg) combinations were compared. Additional evaluations were done on reversal of medetomidine, using atipamezole (200 µ g/kg, IV), after 90 minutes of medetomidine-induced sedation.
Design
Crossover study, with each dog receiving each drug combination at 1-week intervals.
Animals
Six 2-year-old English hound-type dogs.
Procedure
Arterial blood pressure, ECG, respiratory rate, tidal volume, minute volume, arterial blood gas tensions, and serum biochemical variables were measured before, during, and after sedation. Analgesia was evaluated by needle prick on the skin and tail clamp.
Results
Heart rate decreased significantly from 100 beats/mm to <40 beats/min within 3 minutes of injection of medetomidine and medetomidine. and butorphanol (MB). Mean arterial blood pressure in both groups were maintained 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 (PaO2 < 60 mm of Hg) was observed at 10 and 20 minutes in 2 dogs given MB. Atipamezole administration in the dogs given medetomidine significantly increased PaO2 and returned the values to baseline. Needle prick analgesia duration was longer in the medetomidine (80 ± 7.7 minutes) than MB (56.0 ± 19.2 minutes) group. Tail pinch analgesia was variable in both groups. 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.
Clinical Relevance
MB induced a shorter period of analgesia and recumbency than did medetomidine. (Am J Vet Res 1996;57:535–540)
