Determination of Propofol and Isoflurane Anesthesia Depth with Bispectral Index Monitorization in Dogs Undergoing Ovariohysterectomy Procedure

In this study, 12 bitches were used to compare anesthetic depth by bispectral index (BIS) monitoring and vital parameters under propofol and isoflurane anesthesia. The animals were randomly divided into two groups (n=6) for ovariohysterectomy. All animals were premedicated with atropine sulphate (0.04 mg/kg, sc) and midazolam (0.3 mg/kg, iv). The induction of anesthesia was achieved by propofol (5 mg/kg, iv) in groups. General anesthesia was maintained with propofol (0.4 mg/kg/min.) in first group (PRO group) and 2% isoflurane in second group (ISO group). Non-invasive systolic (SAP), diastolic (DAP), mean arterial blood pressure (MAP), heart rate (HR), respiratory rate (RR), haemoglobin oxygen saturation (SpO2) and BIS were measured before anesthesia (0 min, T0), maintenance of anesthesia (T5, T10, T15), end of anesthesia (T30) and additionally BIS also measured at 5 min after the terminating of anesthesia (T35). HR, RR, SAP and DAP did not significantly differ between groups. The MAP value did not show any significant difference within both groups. However, the MAP value detected on T5, T10, T15 and T30 was higher in PRO group than those detected in ISO group (P<0.05). The BIS values detected at all measured times in PRO and ISO groups were lower than those detected before anesthesia. The BIS value detected on T5 and T10 was higher in ISO group, whereas the value determined at T15 was higher in PRO group (P<0.05). In conclusion, it is suggested that bispectral index is a useful tool for monitoring depth of anesthesia in veterinary practice and total intravenous anesthesia with propofol may be used as an alternative to isoflurane anesthesia.