Medetomidine/ketamine anaesthesia in cats

The medetomidine/ketamine combination was evaluated as an anaesthetic in cats undergoing ovariectomy. It was compared with acepromazine/ketamine, xylazine/ketamine and zolazepam/tiletamine combinations. 60 animals, divided into 6 groups of 10 animals were involved. Medetomidine highly potentiated the anaesthetic effects of ketamine and balanced the two main disadvantages of this drug: weak muscle relaxation and poor analgesia in deep organs. 80 micrograms medetomidine/kg--5 mg ketamine/kg provided a duration of anaesthesia longer than 1 mg acepromazine/kg--10 mg ketamine/kg, and not significantly different from those induced by 1 mg xylazine/kg--10 mg ketamine/kg or 7.5 mg zolazepam/kg--7.5 mg tiletamine/kg. Furthermore, it produced a better muscle relaxation than acepromazine/ketamine and zolazepam/tiletamine combinations. The analgesia in deep organs observed after medetomidine/ketamine administration appeared to be more substantial than that observed after acepromazine/ketamine or xylazine/ketamine combinations. The stimulating effect on heart rate of ketamine compensated the bradycardiac effect of medetomidine. Nevertheless, the administration of 80 micrograms medetomidine/kg--5 mg ketamine/kg resulted as with xylazine/ketamine, in decreasing heart rate whereas acepromazine/ketamine and zolazepam/tiletamine combinations did not exhibit bradycardiac effect. It was concluded that the medetomidine/ketamine combination provided a suitable anaesthesia for cats characterized by rapid induction, good muscle relaxation, good analgesia and bradycardia.