Analgesic and motor-blocking action of epidurally administered levobupivacaine or bupivacaine in the conscious dog

Abstract

ObjectiveTo compare the analgesic and motor-blocking effects of epidurally administered levobupivacaine and bupivacaine in the conscious dog. Study designProspective, randomized, cross-over study. AnimalsSix adult female Beagle dogs. MethodsEach animal received three doses of levobupivacaine or bupivacaine (0.5, 1.0 and 1.5 mg kg−1; concentrations 0.25%, 0.50%, and 0.75%, respectively) in a total volume of 0.2 mL kg−1 by means of a chronically implanted epidural catheter. Onset, duration (through pinch response in the sacral, lumbar and toe areas) and degree of analgesia and motor-blocking status was determined with a scoring system and at regular intervals over 8.5 hours before (baseline) and after drug administration. ResultsEpidurally administered levobupivacaine and bupivacaine had a similar dose-dependent analgesic action with no significant differences in onset (range: 5–8 minutes), duration (bupivacaine: 42 ± 28, 135 ± 68 and 265 ± 68 minutes, and levobupivacaine: 28 ± 33, 79 ± 55 and 292 ± 133 minutes; 0.25%, 0.50%, and 0.75%, respectively) or maximum degree of analgesia. However, levobupivacaine tended to produce a shorter duration of motor block than bupivacaine and the difference in the motor to nociceptive blockade times was significant at the highest dose. ConclusionEpidural levobupivacaine produced an analgesic action similar to that of bupivacaine. Clinical relevanceEpidural levobupivacaine is suitable for clinical use in dogs, mostly at the highest dose if a high degree of analgesia is required.