Histologic features of the carotid artery trifurcation in thoroughbreds.

The common, external, and internal carotid and occipital arteries were examined histologically at the trifurcation of the common carotid arteries in 13 Thoroughbred foals (0 to 30 days old) and 64 Thoroughbred adults (2 to 4 years old). Calcification in the media of the common carotid and external carotid arteries was observed in 3 of the 13 foals and in 30 of the 64 adult horses. Calcification resembled that seen in Mönckeberg's arteriosclerosis in human beings, the cause of which is unknown.