Experimental canine atherosclerosis and its prevention. The dietary induction of severe coronary, cerebral, aortic, and iliac atherosclerosis and its prevention by safflower oil.

Severe atherosclerotic lesions were produced without thyroid suppression in seven out of eight dogs by feeding semisynthetic diets containing 5 per cent cholesterol and 16 per cent hydrogenated coconut oil for 12 to 14 months. Occlusive plaques were located in the coronary arteries and major cerebral arteries as well as in the aorta and iliac vessels. The lesions were characterized by an intense sclerotic reaction to areas of lipid deposition and foam cell accumulation in the intima. The diet induced a rapid elevation of plasma-free and esterfied cholesterol, triglyceride, and phospholipid, and the extent of aortic atherosclerosis was shown to be partially dependent on mean plasma cholesterol concentration. A second group of eight dogs were fed a diet identical with the first except for the replacement of 4 per cent hydrogenated coconut oil by 4 per cent safflower oil. Despite receiving the same amounts of dietary cholesterol and fat, this second group of dogs was completely protected from the atherogenic process. Plasma lipids became only slightly elevated and no induced atherosclerotic lesions were found at autopsy. Circulating thyroid hormone concentrations were similar between the two groups of dogs and the thyroid glands had a normal morphology in both groups.