Onset and duration of anaesthesia as well as the changes in vital parameters associated with pentobarbitone-induced anaesthesia in normal dogs administered acetaminophen with and without Silybon 140® were studied. The rectal temperature, heart rates and respiratory rates of dogs before anaesthesia were higher than those after pentobarbitone (35 mg/kg) treatment alone or its combination with acetaminophen or acetaminophen plus Silybon 140®. The acetaminophen and Silybon 140® combination produced the least changes in vital parameters following pentobarbitone treatment. The duration of anaesthesia produced in dogs with pentobarbitone anaesthetic was significantly lower in dogs pre-treated with acetaminophen and Silybon 140® combination compared to those given pentobarbitone alone or its combination with acetaminophen. The dogs pre-treated with acetaminophen (300 mg/kg) had the highest duration of anaesthesia of 437±64 min. These results suggest that pentobarbitone anaesthesia in dogs may be associated with decreased vital parameters. The decrease appears to be more in dogs treated with acetaminophen. The higher duration of anaesthesia and decreased vital parameters in dogs pre-treated with acetaminophen (300 mg/kg) could be associated with hepatotoxic effect of acetaminophen. Silybon 140® given in combination with acetaminophen ameliorated the enhanced vital parameters and duration of pentobarbitone anaesthesia.

Keywords: Dog, acetaminophen, pentobarbitone, anaesthesia, silybon 140®.