A comparison of propofol and alfaxalone in a continuous rate infusion in dogs with mitral valve insufficiency

The aim of this study was to compare alfaxalone and propofol in balanced anaesthesia using midazolam 0.5 mg/kg, xylazine 0.125 mg/kg, butorphanol 0.2 mg/kg intravenously as premedication and the ultrashort acting anaesthetics alfaxalone or propofol for inducing and maintaining in dogs with medically stabilised mitral valve regurgitation. Seven client-owned dogs with a second stage cardiac insufficiency were used in this study. All the dogs suffered from class II cardiac insufficiency according to the classification by the International Small Animal Cardiac Health Council (ISACH). All the dogs were treated with angiotensin converting enzyme inhibitors (enalapril) and diuretics (furosemide), which eliminated the clinical signs of mitral valve regurgitation in all the dogs included in the study. This was a prospective controlled clinical study, 12 months in duration, when the dogs included in the study underwent regular dental prophylaxis. The dogs were monitored electrocardiographically throughout the anaesthesia for the presence of arrhythmias, % oxygen saturation of haemoglobin (%SpO2) measured by pulse oximetry, heart rate, respiratory rate and body temperature. The dogs underwent two anaesthesia procedures with an interval of one year due to the prophylaxis of periodontitis, with the first anaesthesia maintained by propofol and second one by alfaxalone. The respiratory rate was mostly significantly higher in the individuals undergoing alfaxalone anaesthesia (P < 0.05), but neither the slower respiratory frequency in the propofol anaesthesia had any negative impact on the % oxygen saturation of the haemoglobin (%SpO2). The heart frequency was significantly higher in the alfaxalone group (P < 0.005). The arterial blood pressures were comparable, but, on the contrary, the two dogs from propofol group had significantly higher blood pressure. The cardiovascular values in both types of anaesthesia had a tendency to progressively decrease within the physiological range. The level of the analgesia was significantly higher in the case of the propofol anaesthesia (P < 0.01) and the recovery period was also significantly shorter (P < 0.005). It can be concluded that the investigated ultra short acting anaesthetics used in balanced anaesthesia containing subanaesthetic doses of xylazine can be used over one hour of surgical procedures in dogs stabilised for mitral valve regurgitation without a significantly increased risk from the anaesthesia.