Cardiovascular lesions in cobalt-vitamin B12 deficient sheep.

Cardiovascular lesions were observed at necropsy in five of six sheep which were subjected to an experimentally induced cobalt-vitamin B12 deficiency during a period of 34 weeks. The classical symptoms of cobalt-vitamin B12 deficiency (anorexia, cachexia, anaemia) were seen in all six sheep at week 20 of the experiment. Histologically, lesions of the auricular epicardium and myocardium consisted of a high concentration of inflammatory cells dominated by polynuclear eosinophils as well as the haemorrhagic inflammation of blood vessels accompanied by necrosis of auricular tissue. The similarity between the lesions observed in the present experiment and those seen in arteriosclerosis, led to the suggestion that a deficiency of vitamin B12 may be implicated in the pathogenesis of arteriosclerosis. A hypothesis is advanced in this respect.