Pharmacokinetics and anesthetic and cardiopulmonary effects of propofol in red-tailed hawks ( Buteo jamaicensis ) and great horned owls ( Bubo virginianus )

Michelle G. Hawkins Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616.

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Bonnie D. Wright Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.
Pesent address is Veterinary Teaching Hospital, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80525.

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Peter J. Pascoe Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.

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Philip H. Kass Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616.

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Lara K. Maxwell KL Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA 95616.

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Lisa A. Tell Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616.

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Abstract

Objective—To determine induction doses, anesthetic constant rate infusions (CRI), and cardiopulmonary effects of propofol in red-tailed hawks and great horned owls and propofol pharmacokinetics in the owls during CRI.

Animals—6 red-tailed hawks and 6 great horned owls.

Procedure—The CRI dose necessary for a loss of withdrawal reflex was determined via specific stimuli. Anesthesia was induced by IV administration of propofol (1 mg/kg/min) and maintained by CRI at the predetermined dose for 30 minutes. Heart and respiratory rates, arterial blood pressures, and blood gas tensions were obtained in awake birds and at various times after induction. End-tidal CO2 (ETCO2) concentration and esophageal temperature were obtained after induction. Propofol plasma concentrations were obtained after induction and after completion of the CRI in the owls. Recovery times were recorded.

Results—Mean ± SD doses for induction and CRI were 4.48 ± 1.09 mg/kg and 0.48 ± 0.06 mg/kg/min, respectively, for hawks and 3.36 ± 0.71 mg/kg and 0.56 ± 0.15 mg/kg/min, respectively, for owls. Significant increases in PaCO2, HCO3, and ETCO2 in hawks and owls and significant decreases in arterial pH in hawks were detected. A 2-compartment model best described the owl pharmacodynamic data. Recovery times after infusion were prolonged and varied widely. Central nervous system excitatory signs were observed during recovery.

Conclusions and Clinical Relevance—Effects on blood pressure were minimal, but effective ventilation was reduced, suggesting the need for careful monitoring during anesthesia. Prolonged recovery periods with moderate-to-severe excitatory CNS signs may occur in these species at these doses. (Am J Vet Res 2003;64:677–683)

Abstract

Objective—To determine induction doses, anesthetic constant rate infusions (CRI), and cardiopulmonary effects of propofol in red-tailed hawks and great horned owls and propofol pharmacokinetics in the owls during CRI.

Animals—6 red-tailed hawks and 6 great horned owls.

Procedure—The CRI dose necessary for a loss of withdrawal reflex was determined via specific stimuli. Anesthesia was induced by IV administration of propofol (1 mg/kg/min) and maintained by CRI at the predetermined dose for 30 minutes. Heart and respiratory rates, arterial blood pressures, and blood gas tensions were obtained in awake birds and at various times after induction. End-tidal CO2 (ETCO2) concentration and esophageal temperature were obtained after induction. Propofol plasma concentrations were obtained after induction and after completion of the CRI in the owls. Recovery times were recorded.

Results—Mean ± SD doses for induction and CRI were 4.48 ± 1.09 mg/kg and 0.48 ± 0.06 mg/kg/min, respectively, for hawks and 3.36 ± 0.71 mg/kg and 0.56 ± 0.15 mg/kg/min, respectively, for owls. Significant increases in PaCO2, HCO3, and ETCO2 in hawks and owls and significant decreases in arterial pH in hawks were detected. A 2-compartment model best described the owl pharmacodynamic data. Recovery times after infusion were prolonged and varied widely. Central nervous system excitatory signs were observed during recovery.

Conclusions and Clinical Relevance—Effects on blood pressure were minimal, but effective ventilation was reduced, suggesting the need for careful monitoring during anesthesia. Prolonged recovery periods with moderate-to-severe excitatory CNS signs may occur in these species at these doses. (Am J Vet Res 2003;64:677–683)

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