Bacterial aortic endarteritis with sepsis as a rare complication of aortic dissection in a cat

A 14-year-old domestic shorthair cat was examined because of respiratory distress. Thoracic radiography showed a prominent aortic arch and no other abnormalities. Echocardiography documented a mobile flap within the ascending aorta creating 2 lumens, consistent with aortic dissection (AD), mild pericardial effusion with tamponade, left ventricular concentric hypertrophy, and normal left atrial size. Systemic hypertension (200 mmHg) was the presumed cause of AD, prompting administration of telmisartan, furosemide, and amlodipine. The cat clinically improved, became normotensive, and was discharged 2 days later. The cat remained well for 4 months, then became lethargic and died. Necropsy showed a 7.6 cm long aortic intimal flap, severe bacterial aortic endarteritis, and evidence of sepsis including multiple organ necrosis, thrombosis, and embolic glomerulonephritis. Bacterial culture of the kidneys yielded mixed bacterial growth including Pasteurella stomatis, presumably the same bacterium identified in the endarteritis lesion. Infective aortic endarteritis can be a fatal complication of AD.