Evaluation of neuraxial anesthesia in bearded dragons (Pogona vitticeps).

OBJECTIVE: To assess the feasibility, success rate, onset, duration and extent of motor/sensory block following intrathecal injection of lidocaine in bearded dragons (Pogona vitticeps).

STUDY DESIGN: Prospective experimental study.

ANIMALS: A group of eight adult bearded dragons (0.333 ± 0.048 kg).

METHODS: The animals were sedated with alfaxalone (15 mg kg-1 ) subcutaneously. Neuraxial injections were performed with 1% lidocaine (2 mg kg-1 ) or 0.9% sodium chloride (0.2 mL kg-1 ) in all animals with a 7 day interval. If the initial injection did not result in motor block of the pelvic limbs within 10 minutes, a second injection was performed at the same dose. Measurements consisted of bilateral mechanical stimulation of limbs; 25%, 50%, and 75% of the trunk's length; and cloacal tone. Animals were monitored for any untoward side effects by monitoring heart rate (HR), respiratory rate, righting reflex and head position.

RESULTS: Success rate following the first injection of lidocaine was 50% (four out of eight animals) and increased to 75% (six out of eight animals) following a second injection. Onset of motor/sensory block occurred within 5 minutes in all successful injections. Duration and extent were variable, with most bearded dragons presenting motor/sensory block of cloaca and pelvic limbs (six out of six) and 25% of the trunk (five out of six) with mean ± standard deviation (range) duration of 49 ± 28 (25-100), 48 ± 25 (25-90) and 40 ± 14 (25-50) minutes, respectively. Confirmation of intrathecal injection by aspiration of cerebrospinal fluid was not possible. Neuraxial lidocaine significantly increased depth and duration of sedation, with a transient increase in HR, compared with saline.

CONCLUSION AND CLINICAL RELEVANCE: Neuraxial lidocaine is a feasible technique with moderate success rate and low risk of complication in bearded dragons. This technique has potential for improving the management of anesthesia in this species.