Objectives:To compare reaction to injection, sedation and propofol induction dose in dogs receiving acepromazine–buprenorphine pre-anaesthetic medication by the intramuscular or subcutaneous routes.

Methods:Fifty-two client owned dogs of American Society of Anesthesiologists grade I or II anaesthetised for diagnostic imaging. Dogs were randomly assigned to receive acepromazine 0·03 mg/kg and buprenorphine 0·02 mg/kg either intramuscular or subcutaneous. Reaction to injection was scored. Sedation was compared before and one hour after pre-anaesthetic medication. Propofol was administered in 1 mg/kg incremental injections until tracheal intubation was achieved. Total propofol dose was recorded.

Results:Reaction to injection was significantly greater (P=0·009) in the intramuscular group compared to the subcutaneous group. Sedation scores were not significantly different (P=0·523) between the intramuscular and the subcutaneous group. There was no statistically significant difference in propofol dose for induction (P=0·7).

Clinical Significance:Acepromazine–buprenorphine pre-anaesthetic medication provides a similar degree of sedation whether administered by the intramuscular or subcutaneous route. The intramuscular route is more painful compared to the subcutaneous route.