Comparison of morphine, fentanyl, methadone, lidocaine and lidocaine epinephrine as caudal epidural analgesics in donkeys

Caudal epidural analgesia was achieved in five adult donkeys on 5 successiv e occasions using morphine ,fentanyl, lidocaine, lidocaine/epinerphrine and saline (control) into the caudal epidural space at weekly intervals. Analg esia was defined as a lack of response to hemostat pressure and pinprick in the skin of the perineal area and ventral aspect of the tail. The results demonstrated that opioids (morphine 0.1 mg/kg; fentanyl 2 mu g/kg) injected into the epidural space of donkeys did not evoke regional analgesia. Heart , pulse and respiratory rates were not significantly altered by any of the drugs. Neither did the drugs produce any change on the electrocardiogram (E CG) of the animals.