Comparison between lidocaine alone and fentanyl with lidocaine for epidural anaesthesia in dogs

The study was designed to evaluate the benefit of an epidural administration of lidocaine/fentanyl compared with lidocaine alone. Fourteen clinically healthy dogs were administered 0.3 ml/kg 2% lidocaine with 1:200000 epinephrine hydrochloride, 14 received a mixture of 100 mu g fentanyl and 0.3 ml/kg 2% lidocaine with 1:200000 epinephrine hydrochloride via the same route and 7 received 100 mu g fentanyl in 0.3 ml/kg saline with 1:200000 epinephrine hydrochloride. A significantly shortened onset (p < 0.001) and a longer duration (p < 0.01) of analgesia were observed in the group that received the lidocaine/fentanyl mixture. A significant decrease in mean arterial blood pressure was observed in dogs 45 and 60 minutes after the administration of lidocaine (p < 0.01). In conclusion, the addition of fentanyl to lidocaine resulted in effective analgesia with shorter time of spread and greater duration of the analgesic block than the local anaesthetic alone.