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Atherosclerosis is a slow-developing, chronic inflammatory cardiovascular disease syndrome affecting mainly older chickens. It is characterized by the hardening of the arteries, in which plaque material (a combination of fatty substances, cholesterol, calcium, fibrin, and cellular waste products) builds up on artery walls, resulting in the formation of hardened plaques. Over time, this accumulation of plaques cause the arteries to narrow. Without adequate space for blood to flow through the arteries, the connected organs and tissues may not receive enough blood to function properly. Eventually, pieces of the fatty deposits may break off and enter the bird's bloodstream.

Why it Occurs

Atherosclerosis occurs in response to multiple forms of endothelial injuries, most frequently caused by infection with the Marek's disease virus (MDV). Clinical signs of atherosclerosis varies depending on the location of the affected arteries within the body; these can consist of the heart, brain, legs, and/or kidneys. Many times, affected chickens may die acutely or never show any clinical signs of disease.

Necropsy findings

Atherosclerosis lesions consist of accumulations of fats, cholesterol, cellular debris, and inflammatory cells within the vascular media and intima.

Clinical Signs

Difficulty breathing
Enlarged abdomen
Exercise intolerance
Behavioral changes
Weight loss
Chronic weakness
Sudden death


  • History
  • Clinical signs
  • Physical exam
  • Radiographs
  • CBC
  • Necropsy


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Modification of dietSwitch to a low fat diet with supplemental omega 3 fatty acidsH Beaufrere et al.


  • Feeding a balanced, low fat diet
  • Do not expose chickens to second-hand cigarette smoke
  • Do not inbreed
  • Supplement diet with Omega 3 fatty acids

Scientific References

Risk Factors

  • Infection with Marek's Disease virus (MDV) or Chlamydia spp
  • High fat or cholesterol diet
  • Exposure to second-hand cigarette smoke
  • Obesity
  • Cold temperature exposure and stress
  • Hypertension
  • Increasing age
  • Inbreeding
  • Concurrent inflammation
  • Lack of exercise
  • Heavy meat type birds such as broilers and turkeys are highly susceptible to cardiovascular diseases.
  • Roosters are more at risk than hens.
  • Dyslipidemia