A one and a half year old healthy male cross breed dog, weighing 18 kg was anaesthetized by veterinary students for castration surgery at a teaching veterinary establishment. The dog was premedicated with intramuscular 0.05 mg kg
1 acepromazine (Neurotranq, Alfasan, Holland). Anaesthesia was induced by intravenous (IV) co-administration of 0.25 mg kg
1 diazepam (Zepadic, Caspian Tamin Pharmaceutical Co., Iran) and 5 mg kg
1 ketamine (Alfasan, Holland) mixed in the same syringe and administered via a 20 gauge catheter inserted in the right cephalic vein. The dog’s trachea was to be intubated using an 8-mm cuffed tracheal tube in order to maintain anaesthesia with halothane in oxygen. Intubation was performed by a fourth year student, with the aid of a laryngoscope. The endotracheal tube cuff was inflated. However, before the tube could be fixed to the patient or connected to the Y-piece of the anaesthetic circuit, the tube disappeared from sight in the mouth and pharynx. The attendant surgery Resident was not able manually to get hold of or to remove the tube.

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