Complete history: A 4 year old, female spayed mixed breed, 25 kg dog was presented with a history of acute onset of weakness and respiratory distress.

Complete diagnostic investigation: On presentation the dog was lateral and unresponsive, hypothermic, tachycardic, and tachypneic. T-FAST revealed pleural effusion in the right hemithorax. Thoracic radiographs showed widening of the cranial mediastinum with fluid opacity, and moderate amount of pleural effusion on the right side. Thoracentesis revealed non coagulable blood. Hematology revealed normal PCV and total plasma protein (42%/5.8 g/dl, respectively) that dropped to 20%/5 g/dl, and normal platelet count and coagulation profile. The dog was treated with IV fluids, transexemic-acid and FFP. CT examination revealed mild focal widening of the descending thoracic aortic lumen. A small out-pouching of the lumen was noted at the level of the eleventh thoracic vertebra, representing an aortic aneurysm and bleb. Irregular mineralization of the right ventrolateral aortic wall was demonstrated just cranially to the lesion. The descending thoracic aorta was surrounded by a non-enhancing tissue consistent with a peri-aortic hematoma.

Therapy and outcome: Due to the visible defect in the aortic wall, it was assessed that the likelihood of recurrent bleeding was high, a decision was made to attempt treatment with a stent graft. Following general anesthesia, a marker catheter was inserted to the esophagus. A 10 Fr sheath was inserted to the right femoral artery and an angiography catheter was advanced over a wire. As the normal aortic diameter was 10 mm and lesion length was 15 mm, a 50 mm x 12 mm balloon expandable stent graft was chosen. Following angiography, the stent-graft was placed over the wire and deployed under fluoroscopic guidance. The dog recovered uneventfully, with no evidence of recurrent bleeding and was discharged two days following the procedure with antibiotics, anthelmintic, and anticoagulant treatment. At 10-day follow-up, the dog was doing well and stent position was radiographically confirmed.

Discussion: Aortic aneurisms are uncommon and challenging pathology in the veterinary practice with little available treatment options. Stent-graft placement is a minimally invasive option in which a covered stent is placed over the lesion and prevents its rupture.