AbSTRAcT. The present study aimed to evaluate the effect of propofol and thiopental on the plasma oxidant-antioxidant profile in dogs undergoing surgery at doses used to induce anesthesia. The plasma total oxidant status (TOS) and oxidative stress index (OSI) levels increased significantly with time in both groups, whereas the plasma total antioxidant status (TAS) levels decreased with time in both groups. The OSI was significantly higher at the end of surgery than before induction of anesthesia in both groups. The TOS and OSI change ratio of propofol group were significantly lower than that of thiopental group. In conclusion, our findings show that propofol has antioxidant effects in dogs. Further studies need to be conducted to demonstrate the exact mechanism of oxidative stress due to anesthesia and surgery in dogs.

BackgroundAlterations of the normal redox balance might be attributed to increase of plasma free-radical concentration and a disruption of the antioxidant defense system. One of the adverse effects of general anaesthetics is the exogen sources of reactive oxygen radicals that are responsible for several diseases. The purposes of the current study were to evaluate the effect of propofol on oxidative stress and to compare the differences between propofol induction only and induction plus continuous infusion on antioxidant status in dogs.FindingsBeagle dogs were evaluated in the present study. The dogs were assigned randomly to receive three treatments in a crossover model. The three treatments were: group 1 (n = 9), 2% isoflurane; group 2 (n = 9), anaesthesia induced with an intravenous (IV) bolus dose of 6 mg/kg propofol and maintained with 1.5–2% isoflurane; group 3 (n = 9), total IV anaesthesia (induction with 6 mg/kg propofol, infusion with 0.6 mg/kg/min propofol). The results of this study show that dogs exposed to isoflurane had decreased antioxidant enzymes activities, whereas dogs injected with propofol had increased antioxidant enzymes activities.ConclusionsThe results of this study showed that an infusion dose of propofol has antioxidant effects in dogs. These effects may be beneficial to patients in whom free radicals play a role in oxidative stress, such as those with ischemia. Further studies are needed to evaluate whether these antioxidant effects of the anaesthetic are of clinical value.