Atherosclerosis refers to the accumulation of plaque (fatty deposits) in the chicken's arteries. These deposits are made up of cholesterol, fatty substances, cellular waste products, calcium and fibrin. As the plaque build up, the wall of the blood vessel thickens and narrows the channel within the artery. This obstructs blood flow and reduces the supply of oxygen-rich blood to tissues of vital organs in the bird's body.
The most frequently affected site in birds is the aorta at the heart’s base. Other sites of importance include the brachiocephalic trunk, pulmonary artery, dorsal aorta, heart valves, and mural arteries. In all cases, atherosclerotic lesions are more pronounced at the level of, or just before, the branching of smaller arteries. Clinical conditions associated with atherosclerosis in chickens include vascular occlusion, rupture, and thrombosis.
Risk factors for the development of atherosclerosis in chickens include:
- Poor Diet: Consumption of a high-cholesterol diet, a diet low in polyunsaturated fatty acids (PUFA) and high in saturated fatty acids, or a high-fat diet enriched in linoleic acid.
- Viral induced: Infection with the Marek's disease virus, which is known to cause atherosclerotic-like lesions in the arteries.
Clinical Signs of Atherosclerosis in Chickens
Atherosclerosis has been associated with clinical signs in multiple organ systems due to reduced blood flow to critical organs. Most clinical signs are related to poor blood supply to the brain or muscles or to secondary cardiopulmonary disease.
Chickens won't usually develop any clinical signs of the disease until the advanced stages, when the artery is severely narrowed or completely blocked. Many times, the first indication of the disease is sudden death related to an unknown cause. When clinical signs do occur, they are usually associated with cardiac failure, caused by reduced blood flow through the arteries. Which may include anorexia, decreased responsiveness, behavioral changes, lethargy, exercise intolerance, difficulty breathing, darkening of comb, falling off perch, ataxia and sudden death.