A 14 year old giant panda presented with unilateral scrotal swelling. Palpation and conscious ultrasound were suggestive of testicular neoplasia. Anaesthesia was required to obtain radiographs and magnetic resonance imaging (MRI). Immobilisation was achieved with ketamine and medetomidine, and anaesthesia was maintained with sevoflurane in oxygen. Tumours were discovered in both testes and castration was performed. Prior to surgery buprenorphine was administered by slow intravenous injection. Apnoea occurred after approximately 10 mcg/kg had been injected so administration was discontinued. Manual ventilation was required for the majority of the general anaesthetic duration. Spontaneous ventilation returned shortly before transfer to the recovery area. Intramuscular atipamezole administration did not induce a normal recovery; the panda remained profoundly sedated. Further atipamezole had no effect. Due to the apnoea associated with buprenorphine administration during general anaesthesia naltrexone was administered resulting in the panda standing within five minutes post injection.