Abstract

Six healthy adult gopher tortoises (Gopherus polyphemus) were used to determine selected cardiopulmonary effects of intravenous medetomidine and ketamine. Prior to the commencement of this study, carotid and jugular catheters were surgically placed in each animal, for blood collection, direct arterial blood pressure monitoring, and drug administration. Baseline heart rate, direct carotid arterial blood pressure, and body temperature were measured before drug administration, then every 5 min after intravenous injection of medetomidine (100 µg/kg) and ketamine (5 mg/kg). All tortoises were maintained under anesthesia for 30 min, then the effects of medetomidine were reversed with atipamezole (100 µg/kg) administered intravenously. All variables were monitored every 5 min for 15 min following medetomidine reversal. Baseline arterial blood samples were collected before, and at 5, 15, 30 min post-medetomidine/ketamine administration, and 15 min post-atipamezole administration to determine blood pH, PaO₂, and PaCO₂. No significant change occurred in heart rate or body temperature. There was a significant increase in arterial blood pressure following administration of medetomidine/ketamine. There was a significant decrease in arterial blood pressure following administration of the reversal agent, atipamezole. There were also significant changes in blood gas parameters between immobilization and reversal.