Background:

The epidural administration of local anaesthetic agents was advocated for use in any surgical procedure caudal to the diaphragm in dogs but was superior for procedures involving the pelvis, hind limbs, and perineal area. The aim of this study was to determine anaesthetic profiles of bupivacaine (BP) and levobupivacaine (LP) in epidural anaesthesia (EA) and to compare their effects on hemodynamics, blood gases, hematological and biochemical parameters in conscious dogs. Materials, Methods &

Results:

In this study, a total of 20 adult male dogs from different breeds referred to our clinics for castration purposes were used and allocated into two groups; 10 dogs in BP and 10 dogs in LP groups. In this study, each animal received a 0.5% of either BP or LP epidurally, (a fixed total volume of 0.2 mL/kg) followed by 0.3 mL saline solution to flush the dead space in the valve and catheter. Throughout the epidural anaesthesia, heart rate, respiratory rate, systolic and diastolic blood pressure, mean arterial blood pressure, and body temperature were monitored. Similarly, during the study, haematological measurements at 0th, 2nd, 4th, 6th, and 8th h and biochemical measurements at 0th, 2nd, 4th, 6th, 8th and 24th h in blood samples were examined. Simultaneously, blood gases, and Na+ and K+ levels in arterial blood samples were measured at 0th, 30th, 60th, 120th and 240th min. Nocifensive and motor block status were qualitatively assessed at regular intervals baseline, 5, 10, 15, 30, 45, 60, 75, 90, 105, 120 min and every 30 min thereafter. Duration of the analgesia was 124.9 ± 28.6 min in the BP group and 77.5 ± 16.8 min in the LP group (P < 0.05). Motor block duration was determined as 248.2 ± 44.2 min for the BP group and 185.9 ± 38.08 min for the LP group (P > 0.05). Motor and sensory block time was longer in the BP group than in the LP group, and similarly, BP generated sensory and motor block in a shorter period of time. While complete motor block was not observed in two animals in the LP group, complete motor block was seen in all the animals in the BP group. Motor block level was determined as 2.8 ± 0.4 in the LP group and 3 ± 00 in the BP group. There were no statistically significant differences between the levels of motor block. In both groups, decreased heart rate and arterial blood pressure were seen following EA. This decline was higher in the BP group. After epidural anaesthesia, slight decline in respiratory rate and body temperature were observed in both groups. There were no significant differences between the groups regarding cardiopulmonary data. Within each group, statistically significant changes in respiratory rates, body temperatures and blood pressures with regards to times were observed in both groups (P < 0.05).

Discussion:

Similar to the data in the literature, the duration of analgesia and motor block were longer with BP than with LP, and both agents showed close initiation analgesia and motor blockade. The reason for longer motor block by BP may be attributed to its higher lipophilic nature and penetration ability to the myeliniated motor fibrils. In present study, arterial blood pressure dropped, and this was higher in the BP group than in the LP group. These drops were attributed to the ability of sympathetic blockade of BP and LP.