BRIEF COMMUNICATION Continuous infusion of propofol in dogs premedicated with methotrimeprazine Antonio JA Aguiar PhD DepartmentofClinicalSciences,SchoolofVeterinaryMedicine,Sa‹ oPauloStateUniversity,UNESPRuaClo¤ vis Pestana,793,Arac ¸atuba,Sa‹oPaulo16050^680,Brazil Stelio PL Luna PhD DepartmentofVeterinarySurgeryandAnesthesiology,FacultyofVeterinaryMedicineandAnimalScience, Sa‹oPauloStateUniversity^UNESP,DistritoRubia‹oJu¤ nior,Botucatu,Sa‹oPaulo18618^000,Brazil Vale¤ria NLS Oliva PhD , Fla¤ via R Euge“ nio MSc DepartmentofClinicalSciences,SchoolofVeterinaryMedicine,Sa‹ oPauloStateUniversity,UNESPRuaClo¤ vis Pestana,793,Arac ¸atuba,Sa‹oPaulo16050^680,Brazil Gladys B Castro PhD DepartmentofVeterinarySurgeryandAnesthesiology,FacultyofVeterinaryMedicineandAnimalScience,Sa‹ oPaulo StateUniversity^UNESP,DistritoRubia‹oJu¤ nior,Botucatu,Sa‹oPaulo18618^000,Brazil Correspondence: DrAntonioJ.A.Aguiar,DCCRA,MedicinaVeterina¤ria^UNESP,Ca“mpusdeArac ¸atuba,R. Clo¤ visPestana,793, Arac ¸atuba-SP,16050^680,Brazil. Abstract Objective Toevaluatethecardiopulmonaryandclin- ical e¡ects of three di¡erent infusion rates of propofol in dogs premedicated with methotrime- prazine. Studydesign Randomizedexperimentaltrial. Animals Ten healthy adult mixed-breed male and femaledogs,weighingfrom14to20kg. Methods Dogs were premedicated with metho- trimeprazine[1mg kg 1 intravenously(IV)]followed by induction of anesthesia with 4.5mgkg 1 of propofol IV and maintenance with propofol for 60 minutes as follows:T1,0.2 mg kg 1 minute 1 ;T2, 0.3 mg kg 1 minute 1 ;andT3,0.4mgkg 1 minute 1 . Heart rate (HR), respiratory rate (RR), meanarterial pressure (MAP), end-tidal CO 2 (P ET CO 2 ), arterial hemoglobin O 2 saturation, arterial blood gases, and pedal and cutaneous re£exes were measured beforeand5,10,20,30,45and60minutesafterthe beginningof the propofol infusion. Statistical anal- ysiswasperformedusingan ANOVA. Results Heartrateincreasedduringanesthesiainall cases and arterial blood pressure decreased only in dogs intheT3 category. Respiratorydepressionwas proportional to the infusion rate of propofol. Muscle relaxationwassatisfactory,butanalgesiawasinade- quateinthethreetreatments. Conclusions The infusion of 0.2^0.4mgkg 1 minute 1 of propofol produced a dose-dependent respiratorydepression.Thepresenceofapedalwith- drawal re£exand marked cardiovascular responses to this noxious stimulus suggests that anesthesia may not be of su/cient depth for surgery to be carriedout. Clinical relevance Although several studies have been performed using propofol in animals, few studies have investigated the cardiopulmonary andanalgesice¡ectswithdi¡erentdoses.Thedeter- mination of an adequate propofol infusion rate is VeterinaryAnaesthesia and Analgesia, 2001, 28 , 220^224 220