Adverse effects of administration of propofol with various preanesthetic regimens in dogs

<jats:title>Summary:</jats:title> <jats:p>The effects of propofol on anesthetic induction were evaluated in 40 dogs anesthetized with isoflurane. Propofol is a rapidly acting, nonbarbiturate drug that induces anesthesia of ultrashort duration with <jats:sc>iv</jats:sc> administration. Four preanesthetic regimens were used: anesthesia without preanesthetic drugs; or with preanesthetic administration of acepromazine (0.1 mg/kg of body weight, <jats:sc>im</jats:sc>), diazepam (0.2 mg/kg, <jats:sc>iv</jats:sc>), or acepromazine (0.02 mg/kg) and butorphanol (0.4 mg/kg) <jats:sc>im</jats:sc>. Heart rate, systolic arterial blood pressure (<jats:sc>sap</jats:sc>), respiration, quality of induction and recovery, and adverse effects were recorded. Intravenous propofol administration induced a variable period of apnea in 34 of 40 dogs. Cyanosis (in 2 dogs) and signs of pain on injection (in 3 dogs) were infrequently observed during induction. One dog developed ventricular premature depolarizations after propofol administration. Venous CO<jats:sub>2</jats:sub> tension increased and pH decreased immediately after propofol administration, regardless of preanesthetic regimen. The <jats:sc>sap</jats:sc> significantly (<jats:italic>P</jats:italic> < 0.05) decreased after propofol administration in dogs treated with acepromazine (<jats:sc>sap</jats:sc>, 178 mm of Hg before vs 128 mm of Hg after propofol) and with acepromazine/butorphanol (<jats:sc>sap</jats:sc>, 184 mm of Hg before vs 98 mm of Hg after propofol). When used for induction, propofol induces anesthetic-related adverse effects, some of which can be minimized by preanesthetic medication. Recovery characteristics varied with preanesthetic medication, independent of propofol administration.</jats:p>