Spontaneous and Stress-Induced Myocardial Infarction in Aged Atherosclerotic Dogs

Abstract

Male, mongrel dogs, six to eight years of age, were placed on an atherogenic regimen which included I¹³¹ administration and/or thiouracil with cholesterol feeding and, in some cases, the addition of 10 per cent lard to the diet. As is usually observed in such experiments, the degree of hypercholesterolemia and atheromatosis varied greatly. However, in nine out of ten dogs with blood cholesterol levels of 1,800 mg. per cent or above for over 16 weeks, myocardial infarction appeared (a) spontaneously, (b) after pitressin administration, and (c) after exposure to a stresser. Myocardial infarction has been noticed only rarely previously. Reasons are given for the belief that the advanced age of the animals which were used here played a role in the genesis of infarction.