Effects of epidural anesthesia with tramadol, ropivacaine or tramadol-ropivacaine combination, in bitches undergoing ovariohysterectomy under anesthesia with isoflurane

Epidural anesthesia is a locoregional anesthetic technique that provides analgesia and muscle relaxation in the-retroumbilical region. The combination of opioids and local anesthetics increased the intensity and duration of analgesia by causing immediate motor and sensory nerve blockade, and improved recovery after surgery. The objective was to comparatively evaluate the trans- and postoperative cardiorespiratory and analgesic effects of epidurally administered tramadol, ropivacaine and tramadol-ropivacaine combination in dogs undergoing elective ovariohysterectomy. The effect of isoflurane concentration was also evaluated. This study was performed on 24 female mongrel dogs, pre-medicated with chlorpromazine (0.5 mg kg-1, IV) and, anesthetized with propofol and isoflurane. The dogs were randomly divided into three groups. The first group receveid epidural tramadol (2 mg kg-1, GT group), the second group received ropivacaine (1.5 mg kg-1, GR group), and the third group received a tramadol-ropivacaine combination at the above-mentioned doses (GTR group). At pre-defined time points, classified into pre-, trans-, and postoperative periods, cardiorespiratory variables and analgesia were analyzed for a period of up to 420 min following epidural anesthesia. The check analgesia was check of approximately 105, 217 and 382 minutes, in GR, in GT and GTR respectively, and no cardiovascular and respiratory depression. The drugs used in this study are considered safe and effective for ovariohysterectomy due to the cardiorespiratory stability and trans-operative analgesia provided by them. However, the combination of ropivacaine and tramadol ensured a greater reduction in the inhaled anesthetic dose and better analgesia during in the postoperative period.