Aortic - Iliac Thrombosis in Bovine

Abstract

Blood is maintained in a fluid form within the vascular system by the body maintaining a balance between the clotting mechanism, fibrin and platelets deposition on the one hand and the activity of fibrinolytic enzymes on the other. Thrombosis occurs if the clotting mechanism and the fibrin and platelets deposition within the vascular system become excessive and exceeds the fibrinolytic activity of the fibrinolysin. Three factors known as the Virchow's triads consisting of damage to vessel wall and endothelium, changes in the blood flow and changes in the composition of the blood are generally considered to constitute the main pathogenetic mechanism of thrombosis. Because of the low blood pressure and the nature of the blood flow on the veinous side of the circulation, veinous thrombosis occurs more commonly than arterial thrombosis.

Arterial thrombosis involving either the aorta, cranial messenteric artery, coronary artery or iliac arteries are commonly known to occur in horses infected with Strongylus vulgaris, in cats with idiopathic cardiomyopathy and in man due to atheriosclerosis or atheromas. In cattle most cases of thrombosis reported involved the caudal vena cava (1,2,3,). Thrombosis affecting smaller arteries and arterioles in cattle are known to occur in malignant catarrhal fever as the result of fibrinoid degeneration and arteritis or arteriolitis and in infection with Haemophilus somnus which causes ischaemic septicaemic thrombomeningoencephalitis. Thrombosis affecting larger arterial blood vessels are rare. This paper describes unique cases of extensive thrombosis of the aorta, it's branches and the iliac arteries in three cows examined at postmortem.