Evaluation of neuraxial anesthesia in bearded dragons (Pogona vitticeps)

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

Prospective experimental study.

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

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.

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.

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.