Pathological effects of intra-arterial blood transfusions in dogs.

During storage, large cellular aggregates and clots formed in venous blood but not in arterial blood. Contrary to previous opinions, the intra-arterial transfusion of blood containing aggregates and clots did not cause focal brain damage and the presence of aggregates was not essential for the post-transfusion development of cerebral petechial and other minor haemorrhages.