Effects of intramuscular administration of low doses of medetomidine and medetomidine-butorphanol in middle-aged and old dogs

摘要

The effects of low doses of medetomidine administered with and without butorphanol and glycopyrrolate were studied in 88 healthy middle-aged (>5 years) and old dogs. Dogs were assigned randomly to receive medetomidine (2, 5 or 10μg/kg body weight,i.m.) alone or with glycopyrrolate (0.01 mg/kg, s.c.), medetomidine (10μg/kg) and butorphanol (0.2 mg/kg, i.m.) or medetomidine (10μg/kg), butorphanol (0.2 mg/kg), and glycopyrrolate (0.01 mg/kg). Anaesthesia was induced with thiopental sodium and maintained with isoflurane. Degree of sedation and analgesia were determined before and after medetomidine administration. Respiratory rate, heart rate and mean arterial blood pressure were determined 10 and 30 min after medetomidine administration. Sedationincreased after medetomidine administration in 79 of 88 dogs, but decreased in 7 dogs that received 2 or 5μg of medetomidine/kg. Mean post-sedation analgesia score and amounts of thiopental and isoflurane used were less in dogs that received medetomidine and butorphanol compared with other groups. Respiratory rate, heart rate and blood pressure were not different among groups. Significantly more adverse effects developed in dogs that did not receive glycopyrrolate. It is concluded that i.m.administration of medetomidine (10μg/kg) and butorphanol (0.2 mg/kg) induce sedation and analgesia and reduce amounts of thiopental and isoflurane required for anaesthesia in middle-aged and old dogs and that glycopyrrolate decrease frequency of medetomidine-associated adverse effects.