Twenty-eight dogs were randomly allocated into two groups. They were premedicated with either 10 or 20 microg/kg
buprenorphine and 0.05 mg/kg
acepromazine administered intramuscularly, and then anaesthetised with intravenous
thiopentone to effect and maintained with
isoflurane in 100 per cent
oxygen. The dogs underwent routine
castration, and a second dose of 10 microg/kg
buprenorphine was administered four hours after the first or 20 microg/kg six hours after the first dose. Levels of
pain and sedation were scored on a visual analogue scale and in terms of the dogs' requirement for rescue
analgesia, and mechanical nociceptive thresholds were measured at the hock and
wound at
premedication and one, two, three, four, five, six, seven, 10 and 21 to 22 hours later.
Pain scores were low in both groups, with a trend for lower scores in the high dose group; administration of the second dose of
buprenorphine further decreased the
pain scores.
Buprenorphine produced good preoperative sedation and the level of sedation decreased over time after surgery. Administration of the second high dose of
buprenorphine did not increase the level of sedation. Both doses of
buprenorphine prevented
hyperalgesia at the
wound and hock postoperatively. Three dogs given the low dose and one dog given the high dose required rescue
analgesia with
carprofen.