Anaesthesia was induced with alfaxalone to effect [ 0.2 mgkg ( -1 ) intravenously ( IV ) every 20seconds ] , initially maintained with 8mgkg ( -1 ) hour ( -1 ) alfaxalone IV and infusion adjusted ( 0.5 mg kg ( -1 ) hour ( -1 ) ) every five minutes according to alterations in heart rate ( HR ) , respiratory rate ( fR ) , Doppler blood pressure ( DBP ) and presence of palpebral reflex .