Comparison of intramuscular medetomidine versus medetomidine-vatinoxan sedation in bearded dragons (Pogonavitticeps)

Abstract

Objective: To assess sedation following intramuscular (IM) administration of medetomidine versus medetomidine-vatinoxan in bearded dragons.

Study design: Prospective, randomized, experimental, crossover study.

Animals: A group of 10 (five males and five females) bearded dragons (mean mass ± standard deviation 172 ± 28 g).

Methods: All animals were administered both medetomidine (0.2 mg kg^-1) (MED) and medetomidine (0.2 mg kg^-1)-vatinoxan (4 mg kg^-1) (MED-VAT) IM, with a 14-16 day washout period between treatments. Sedation was assessed using an adapted version of a sedation scale for bearded dragons (scale range 0-12) before (T0), and every 5 minutes from 10 to 45 minutes after treatment administration (T10-T45). Sedation scores were compared: 1) between time points (within treatments) using a Friedman test and Dunn's post hoc test; and 2) between treatments at each time point using a Wilcoxon paired test. Heart rate and respiratory rate (f_R) were analyzed descriptively. At T45, atipamezole was administered IM.

Results: Compared with T0, sedation scores were significantly higher at most time points for both treatments. Highest median (range) scores occurred at T30 for MED [T0, 0 (0-0); T30, 2.5 (1-5); p = 0.0001] and at T35 and T40 for MED-VAT [T0, 0 (0-0); T35, 2 (1-5); p = 0.002; T40, 2 (1-5); p = 0.001]. No significant differences in sedation scores were identified between treatments at any time point. The two protocols caused bradycardia and reduction in f_R. All animals were active and ate 1 hour after reversal administration.

Conclusions and clinical relevance: Both medetomidine and medetomidine-vatinoxan caused similar mild sedation in bearded dragons (median < 3/12). Inclusion of vatinoxan did not enhance sedation in this species.

Keywords: MK-467; lizard; reptiles; α(2)-adrenoceptor agonist; α(2-)adrenoceptor antagonist.