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Abstract

The objective of this study was to evaluate and compare the postoperative analgesia provided by epidural lidocaine, lidocaine and morphine or lidocaine and tramadol in dogs following elective orchiectomy or ovariohysterectomy. Thirty-six clinically healthy dogs, classified as class I and II according to the American Society of Anesthesiologists classification system, were randomly allocated into three groups of 12 each, with six females and six males. The dogs received 4mg/kg of lidocaine combined with 0.01ml/kg of 0.9% NaCl, 0.1mg/kg of morphine or 1.0mg/kg of tramadol epidurally. Postoperative pain was assessed 4, 8, 12, 18 and 24 hours after epidural anaesthesia using the University of Melbourne pain scale (UMPS), by a single male observer who was blinded to the epidural protocol. According to the obtained results, evaluated epidural protocols provided sufficient and comparable postoperative analgesia throughout the complete 24-hours observation period. The appearance of vocalization or painful reaction to palpation of the wound surrounding tissue were absolutely absent. Values of 10 points, or higher, indicating the presence of moderate to severe pain and the necessity of additional analgesia, were not recorded. However, established quality of postoperative analgesia is probably not the sole result of epidural administration of drugs, but also analgesic activity of drugs used for general anaesthesia (xylazine and ketamine), and their mutual synergistic or additive effects.