Effects of simultaneous cholesterol loading upon vitamin D toxicosis in dogs

Histopathological investigation of the distribution and characteristics of the lesions in beagle dogs given excessive vitamin D2 was undertaken with special attention to changes in the vascular system. At the same time, the effects of simultaneous cholesterol loading upon these lesions were also examined. Oral administration of vitamin D2 at the dose of 480, 000 I.U./kg/day for 21 days produced medial edema, disorganization of the elastic laminae and degeneration of smooth muscle cells in the aorta, and intimal edema, disruption of calcified internal elastic lamina and proliferation of smooth muscle cells in the coronary arteries. Metastatic calcification was observed in the lungs, trachea, kidneys, thyroid glands, parathyroid glands, choroid plexus, submandibular and parotid glands, prostate, stomach and retina. Simultaneous cholesterol loading at the dose of 300 mg/kg/day showed an additional deleterious effects on these changes, leading to the so-called Monckeberg's type sclerosis in the aorta characterized by the complex deposition of calcium, polysaccharides and a little amount of lipids in the media.