Short Communication| Volume 47, ISSUE 6, P793-796, November 2020

Effects of intracoelomic alfaxalone–dexmedetomidine on righting reflex in common garter snakes (Thamnophis sirtalis): preliminary data

Published:August 12, 2020DOI:



      To evaluate the effect of dexmedetomidine on alfaxalone immobilization in snakes.

      Study design

      Nonblinded, crossover study.


      A total of eight mature common garter snakes (Thamnophis sirtalis).


      Snakes were administered each of three treatments intracoelomically: alfaxalone (30 mg kg–1; treatment A), alfaxalone (30 mg kg–1) combined with dexmedetomidine (0.05 mg kg–1; treatment AD0.05); and alfaxalone (30 mg kg–1) combined with dexmedetomidine (0.10 mg kg–1; treatment AD0.10). A minimum of 10 days elapsed between experimental trials. Times to loss of righting reflex (LRR) and return of righting reflex (RRR) were recorded. Heart rate (HR) was recorded every 5 minutes throughout the period of LRR and averaged for each snake. Times to LRR and RRR, and mean HR in snakes that achieved LRR were reported.


      LRR occurred in eight (100%), five (63%) and three (38%) snakes in treatments A, AD0.05 and AD0.10, respectively. For all treatments, time to LRR ranged 3–20 minutes. Median (range) times to RRR were 39 (30–46), 89 (62–128) and 77 (30–185) minutes for treatments A, AD0.05 and AD0.10, respectively. In animals where righting reflex was lost, mean HR was lower in all dexmedetomidine treatments compared with treatment A.

      Conclusions and clinical relevance

      In this pilot study, alfaxalone resulted in reliable immobilization, whereas dexmedetomidine and alfaxalone combinations resulted in highly variable durations of immobilization with low HR in immobilized animals. For snakes that achieved LRR, the addition of dexmedetomidine (0.05 mg kg–1) to alfaxalone appeared to extend the period of immobilization compared with alfaxalone alone.


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        • Bennell P.M.
        • Whittem T.
        • Tudor E.
        A controlled randomized clinical trial to assess postoperative analgesia after thiopental-isoflurane anaesthesia or total intravenous anaesthesia with alfaxalone in dogs.
        J Vet Pharmacol Ther. 2019; 42: 268-277
        • Bessler S.M.
        • Stubblefield M.C.
        • Ultsch G.R.
        • Secor S.M.
        Determinants and modeling of specific dynamic action for the Common Garter Snake (Thamnophis sirtalis).
        Can J Zool. 2010; 88: 808-820
        • Bunke L.G.
        • Sladky K.K.
        • Johnson S.M.
        Antinociceptive efficacy and respiratory effects of dexmedetomidine in ball pythons (Python regius).
        Am J Vet Res. 2018; 79: 718-726
        • Doss G.A.
        • Fink D.M.
        • Sladky K.K.
        • Mans C.
        Comparison of subcutaneous dexmedetomidine–midazolam versus alfaxalone–midazolam sedation in leopard geckos (Eublepharis macularius).
        Vet Anaesth Analg. 2017; 44: 1175-1183
        • James L.E.
        • Williams C.J.
        • Bertelsen M.F.
        • Wang T.
        Anaesthetic induction with alfaxalone in the ball python (Python regius): dose response and effect of injection site.
        Vet Anaesth Analg. 2018; 45: 329-337
        • Scheelings T.F.
        • Baker R.T.
        • Hammersley G.
        • et al.
        A preliminary investigation into the chemical restraint with alfaxalone of selected Australian squamate species.
        J Herpetol Med Surg. 2011; 21: 63-67
        • Schnellbacher R.
        • Hernandez S.M.
        • Tuberville T.
        • et al.
        The efficacy of intranasal administration of dexmedetomidine and ketamine to yellow-bellied sliders (Trachemys scripta scripta).
        J Herpetol Med Surg. 2012; 22: 91-98
        • Sladky K.K.
        • Mans C.
        Clinical anesthesia in reptiles.
        J Exot Pet Med. 2012; 21: 17-31
        • Sleeman J.M.
        • Gaynor J.
        Sedative and cardiopulmonary effects of medetomidine and reversal with atipamezole in desert tortoises (Gopherus agassizii).
        J Zoo Wildl Med. 2000; 31: 28-35
        • Strahl-Heldreth D.E.
        • Clark-Price S.C.
        • Keating S.C.J.
        • et al.
        Effect of intracoelomic administration of alfaxalone on the righting reflex and tactile stimulus response of common garter snake (Thamnophis sirtalis).
        Am J Vet Res. 2019; 80: 144-151