Anaesthesia of a Sumatran tiger on eight occasions with ketamine, medetomidine and isoflurane

Case. An 18-month-old male Sumatran tiger was referred for endoscopy and di latation of an oesophageal stricture. Anaesthesia and bouginage was underta ken on eight occasions 2-3 weeks apart to dilate the oesophageal stricture. Clinical findings. On the first occasion, sedation was induced with a combi nation of medetomidine (30 mu g/kg) and ketamine (2.35 mg/kg) given intramu scularly. Cardiopulmonary depression (chararcterised by bradycardia, ventri cular arrhythmias, hypoventilation and cyanosis) was severe and in subseque nt anaesthesias the medetomidine dose was decreased to about 18 mu g/kg and the ketamine dose increased to about 3 mu g/kg given intramuscularly. Immo bilisation was adequate and the severity of the cardiopulmonary depression was reduced at the revised drug dosages. Atipamezole was effective in rever sing both the cardiopulmonary and central nervous system depression. Conclusion. The dosage of medetomidine and ketamine recommended in the lite rature for immobilising tigers produced severe cardiopulmonary depression i n this animal. A reduced dosage of medetomidine and higher dosage of ketami ne provided adequate restraint with decreased cardiopulmonary depression.