Evaluation of neuraxial administration of bupivacaine in bearded dragons (Pogona vitticeps)

Abstract

Objective

To assess the success rate, onset, duration and extent of motor/sensory block following neuraxial injection of two dosages of bupivacaine in bearded dragons (Pogona vitticeps).

Study design

Prospective, randomized, blinded, crossover experimental study.

Animals

A total of 10 adult bearded dragons (0.3 ± 0.1 kg).

Methods

After sedation with alfaxalone (15 mg kg^–1 subcutaneously), neuraxial injections were performed with 1 or 2 mg kg^–1 bupivacaine hydrochloride (0.5%, treatments BUP-1 and BUP-2, respectively) in a randomized treatment sequence with a 7 day washout period. If the initial bupivacaine injection was not successful within 10 minutes, a second injection was performed at the same dose. Mechanical stimulation of limbs, 25%, 50%, 75% of the trunk’s length and cloacal tone were assessed.

Results

Success rate following the first neuraxial injection was 95%, which increased to 100% after the second injection. Motor/sensory block were noted by 5 minutes after the injection of bupivacaine at either dose. BUP-2 was associated with more cranial spread. The median (range) duration of cloacal tone loss was longer following treatment BUP-2 [120 (75–225) minutes] than followed treatment BUP-1 [83 (25–135) minutes; p = 0.03]. Duration of pelvic limb motor block was comparable between both doses, lasting a median of 68 minutes in both treatments (p = 0.94). There was a transient, not clinically relevant increase from baseline in heart rate in treatment BUP-1 only. No significant difference from baseline in respiratory rate was noted in either treatment; however, two animals in treatment BUP-2 became apneic (10–20 minutes).

Conclusions and clinical relevance

Bupivacaine (1 mg kg^–1) is recommended for neuraxial anesthesia in bearded dragons. In treatment BUP-2, extensive cranial spread resulted in apnea and motor block of the thoracic limb in several animals; therefore this dose is not recommended.