Anaesthesia recovery quality after racemic ketamine or S-ketamine administration to male cats undergoing neutering surgery

Postoperative anaesthesia recovery and analgesia qualities were compared in cats anaesthetised with racemic ketamine (RS-ket) or S-ketamine (S-ket) undergoing orchiectomy. Twenty client-owned male cats received medetomidine (0.03 mg/kg) and S-ket (6 mg/kg; n = 10) or RS-ket (10 mg/kg; n = 10), all intramuscularly. After routine orchiectomy, animals received atipamezole (0.15 mg/kg) intramuscularly. Thirty and 60 min after atipamezole administration, one observer unaware of the treatment identity evaluated analgesia using a visual analogue scale (VAS) and, by means of four points scales, sedation, unprovoked behaviour and behavioural reactions to external stimuli. Cats with a VAS > or = 15 mm were to receive butorphanol. Times to sternal and standing positions were recorded. After 60 min, cats were given carprofen (4 mg/kg) subcutaneously. Anaesthesia with S-ket, at 60% of the RS-ket dose, provided faster recoveries. At 60 min, undisturbed cats in S-ket group had a trend towards fewer behavioural changes. Cats in RS-ket group were more sedate at 30 min and responded with a lower intensity to external stimulation. Immediate postoperative analgesia was considered adequate for both groups and no cat required butorphanol administration.