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

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 IV administration. Four preanesthetic regimens were used: anesthesia without preanesthetic drugs; or with preanesthetic administration of acepromazine (0.1 mg/kg of body weight, IM), diazepam (0.2 mg/kg, IV), or acepromazine (0.02 mg/kg) and butorphanol (0.4 mg/kg) IM. Heart rate, systolic arterial blood pressure (SAP), respiration, quality of induction and recovery, and adverse effects were 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 CO2 tension increased and pH decreased immediately after propofol administration, regardless of preanesthetic regimen. The SAP significantly (P < 0.05) decreased after propofol administration in dogs treated with acepromazine (SAP, 178 mm of Hg before vs 128 mm of Hg after propofol) and with acepromazine/butorphanol (SAP, 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.