Effects of methadone or neostigmine in combination with lidocaine for epidural anesthesia in dogs

Six mature mongrel dogs of both genders, weighing 13.3±3.4kg (mean±SD) were used in the present research. Thirty minutes after premedication with intravenous acepromazine (0.1mg/kg, IV), dogs were randomly assigned to receive epidural administration of one of following three treatments: 2% lidocaine 0.25ml/kg (control), or neostigmine 0.01mg/kg plus lidocaine (NEO), or methadone 0.3mg/kg plus lidocaine (MET). All dogs received all treatments in a cross-over design with at least one-week interval. Heart rate (HR), respiratory rate (RR), systolic arterial pressure (SAP), time to loss of pedal withdrawal reflex, duration of epidural anesthesia, and cranial spread of epidural anesthesia were evaluated for 90 minutes. No differences among treatments in HR, RR, SAP, duration of anesthesia, and time to loss of pedal withdrawal reflex were found. In MET, HR decreased from 30 to 90 minutes compared to baseline and there was a higher cranial spread of epidural anesthesia than in controls and NEO animals. Neostigmine or methadone did not prolong epidural anesthesia with lidocaine in dogs. Methadone, but not neostigmine, appeared to result in more cranial spread of epidural anesthesia with lidocaine.

dog; epidural anesthesia; methadone; neostigmine; lidocaine