Efficacy of two methods of intranasal administration of anaesthetic drugs in red-eared terrapins (Trachemys scripta elegans)

The aim of the study was to evaluate the efficacy of ketamine, dexmedetomidine, atipamezole and alfaxalone delivered by two methods of intranasal administration in terrapins. The two methods were used in 21 healthy adult female red-eared terrapins: (A) with fully extended neck and restrained head, (B) with head hidden inside the shell. Ketamine (10 mg/kg) and dexmedetomidine (0.2 mg/kg) were delivered using a micropipette in the left and the right naris, respectively. Atipamezole (2 mg/kg) was administered 60 minutes later. Heart rate, head withdrawal reflex, palpebral reflex, toe-pinch reflex on the pelvic limb and glottal control enabling the insertion of the tracheal tube were recorded at 10-minute intervals. After a washout period of six months, alfaxalone (5 mg/kg) was tested. The first measurement in the alfaxalone trial started 5 minutes after the drug was administered and continued at 10-minute intervals. Heart rate decreased significantly in response to both methods of ketamine and dexmedetomidine administration. There were no significant differences between methods in time to loss of reflexes and full recovery of reflexes. Intranasal administration of atipamezole enabled rapid return to full activity. Alfaxalone administration decreased heart rate non-significantly and did not result in loss of evaluated reflexes. Both methods of drug administration of ketamine, dexmedetomidine and atipamezole resulted in a safe form of sedation and recovery. Intranasal administration of 5 mg/kg of alfaxalone was not effective.