ABSTRACT:The paper describes a double symmetrical aortic arch in a dog trapping the oesophagus. Thoracotomy was performed in the fourth inter-costal space under general, isoflurane-maintained, anaesthesia. Cutting of the arterial ligament failed to free the oesophagus. Dissection of further vascular structures revealed the left and right aortic arches to be of similar diameter. A vascular clamp was put on the left arch for 10 min, while the patient's cardiovascular parameters were monitored. The lack of significant cardio-respiratory symptoms indicated the necessity of ligating and cutting the left aortic arch. Removal of additional tissue from the region of the cut on the left arch completely released the oesophagus which was continuously monitored by video-oesophagoscopy. The chest was closed according to a standard thoraco-surgical procedure. The cutting of the left aortic arch and the release of the surrounding tissue restored the normal position of the oesophagus. After surgery, the animal was returned to its owners in a very good condition. Control examination showed complete amelioration of clinical symptoms and subsequent normal development of the dog. Intra-operative clamping of the left aortic arch with simultaneous monitoring by oesophagoscopy ensured a positive outcome of the surgery of the intra-operatively diagnosed double aortic arch.