Anesthetic efficacy of dexmedetomidine-ketamine in eastern box turtles (Terrapene carolina carolina) is enhanced with the addition of midazolam and when administered in the forelimb versus the hindlimb.

OBJECTIVE: To compare dexmedetomidine-ketamine (DK; 0.1 and 10 mg/kg, respectively) with midazolam (M; 1.0 mg/kg) or 0.9% sodium chloride (S; 0.2 mL/kg) administered IM in the forelimb (F) or hindlimb (H) in eastern box turtles (Terrapene carolina carolina).

ANIMALS: 20 clinically healthy, captive adult eastern box turtles.

METHODS: In a randomized, blinded, complete crossover study with 1-week washout periods, turtles were administered each of 3 treatments: F-DKS, F-DKM, or H-DKM. Palpebral reflex, muscle tone, and withdrawal responses were serially assessed and used to calculate cumulative sedation scores at each 5-minute time point. The ability to intubate was evaluated. At 60 minutes, atipamezole (1.0 mg/kg) and either flumazenil (F-DKM, H-DKM; 0.05 mg/kg) or 0.9% sodium chloride (F-DKS; 0.5 mL/kg) were administered IM.

RESULTS: All treatments resulted in clinically relevant anesthetic effects. F-DKM produced significantly higher sedation scores than H-DKM or F-DKS at all time points between 10 and 60 minutes (P < .05). Sedation score variability was observed with all treatments with significantly higher variability for H-DKM (P < .05). Intubation was successful in 32, 89, and 11% of turtles in F-DKS, F-DKM, and H-DKM, respectively. Median (range) recovery time was 10 (5-22), 16 (7-45), and 12 (4-28) minutes for F-DKS, F-DKM, and H-DKM, respectively.

CLINICAL RELEVANCE: In eastern box turtles, forelimb dexmedetomidine-ketamine resulted in clinically relevant anesthetic effects that were heightened with the addition of midazolam. Hindlimb administration of midazolam-dexmedetomidine-ketamine resulted in reduced and more variable anesthetic effects compared to forelimb administration, supporting a hepatic first-pass effect.