Comparison of intraocular pressure, tear production and cardiorespiratory variables before and after induction of anaesthesia with either propofol or ketofol in dogs premedicated with midazolam

The objective of the present study was to compare the effects of propofol and ketofol on intraocular pressure, tear production and cardiorespiratory variables in dogs premedicated with midazolam. Six castrated adult mixed-breed dogs were used in a cross-over design with a one-week interval. Twenty minutes after premedication with midazolam (0.2 mg/kg), animals were assigned randomly to two groups and received either propofol (6 mg/kg) or ketofol (3 mg/kg; 1 : 1 mg/ml ratio) treatments intravenously. Intraocular pressure, tear production, heart rate, respiratory rate, rectal temperature and direct mean arterial blood pressure were measured at base (before induction), and at 5, 10, 15, 20 and 30 min after induction of anaesthesia. Blood gas samples were obtained at base (before induction), and at 5, 15 and 30 min after administration of treatments. Intraocular pressure showed significantly higher values at 5 min after induction in ketofol compared with propofol (16.1 ± 4.5 mm Hg vs 8.2 ± 1.2 mm Hg, respectively). There were no significant changes in tear production in either group. Significantly higher heart rate and mean arterial blood pressure were detected in ketofol at several time points. Respiratory depression occurred in both groups with no significant differences between them. In conclusion, although ketofol improved heart rate and mean arterial blood pressure and did not elicit more pronounced respiratory depression than propofol, it resulted in significantly higher values of intraocular pressure at 5 min after administration in dogs. Despite the small number of dogs in this study, our results indicate that ketofol should not be recommended for ophthalmic surgical procedures in dogs. Appropriate oxygenation should be provided when propofol is used for ophthalmic surgeries.