However, necropsy surveys may underestimate the prevalence of this disease because it cannot be diagnosed solely on the basis of gross examination.Factors that predispose birds to the development of atherosclerosis remain unclear, but hyperlipidemia, endothelial inflammation, toxic substances, immune complex disease, species of bird, inappropriate longterm diet (high fat or cholesterol intake), and lack of exercise have been implicated. 1 Median age of affected adult birds typically ranges from < 2 to 13 years. No sex predisposition is evident. 2,3 Birds appear to be more susceptible to the development of atherosclerosis than are any mammals, except for humans. 4 Avian species affected by atherosclerosis include many orders of birds, which range from domestic species to those maintained in zoologic collections. Most atherosclerosis studies in birds have involved investigations of turkeys, Japanese quails, chickens, or pigeons. 5 Each order of bird develops atherosclerotic plaques in a different location, which suggests that slightly different mechanisms may exist for each species. The most common location is the aorta at the base of the heart, but plaques may also develop in the brachiocephalic artery, pulmonary artery, descending aorta, heart valves, and mural coronary arteries. 6 Except for turkeys, all birds studied do not have aneurysmal dilation, which is in contrast to humans with atherosclerosis. 6 Risk factors for development of atherosclerosis include increases in plasma cholesterol, VLDL, intermediate-density lipoprotein, LDL, LDL a , and apoprotein B concentrations. Decreased concentrations of HDL, particularly HDL 2 , and apoprotein A 1 are also risk factors