Turkeys can experience sudden, fatal cardiovascular events often referred to as “heart attacks.” While these birds rarely suffer from the coronary artery plaque buildup that causes most human heart attacks, their rapid growth predisposes them to catastrophic cardiac and vascular failures. The intense selection for breast muscle mass has created a mismatch between the body’s size and the capacity of the heart and lungs to support it. This biological vulnerability, when combined with environmental or physical stress, results in distinct sudden death syndromes. These health issues primarily affect rapidly growing, heavier male turkeys, which experience the highest mortality rates.
The Phenomenon of Sudden Turkey Death
The most commonly recognized forms of sudden mortality in commercial flocks are Sudden Death Syndrome (SDS) and Aortic Rupture. SDS typically affects healthy, fast-growing male turkeys between 8 and 19 weeks of age. Birds succumbing to this condition often collapse without any preceding clinical signs, indicating an acute systemic failure. Mortality rates generally range from 0.5% to 2%, but can occasionally climb higher in affected flocks.
Aortic Rupture, or dissecting aneurysm, is a noninfectious cardiovascular disorder that results in sudden death. This condition involves the bursting of the aorta, the body’s main artery, which leads to massive internal hemorrhage into the body cavity. The highest incidence is usually observed between 12 and 16 weeks of age. Post-mortem examination reveals a pale carcass and a large blood clot in the abdominal cavity.
Key Physiological Causes of Cardiac Failure
Sudden deaths in turkeys are rooted in two primary physiological issues: a compromised heart structure and a weakened vascular system. One major condition is Round Heart Disease (RHD), or Spontaneous Turkey Cardiomyopathy (STC), which involves an enlarged and poorly functioning heart. In young poults, this condition is characterized by the dilation of both the right and left ventricles, leading to congestive heart failure. In older birds, the syndrome is associated with hypertrophic cardiomyopathy, where the heart muscle thickens, often secondary to high systemic blood pressure.
Structural weaknesses in major blood vessels compound the heart’s inability to efficiently pump blood. The aorta, particularly in the abdomen, is prone to developing degenerative changes in its middle layer, the tunica media. This flaw predisposes the vessel to a dissecting aneurysm, where the wall splits longitudinally and eventually ruptures. The integrity of the aortic wall relies heavily on connective tissues like collagen and elastin.
The synthesis of strong collagen depends on the trace mineral copper. A deficiency in this mineral can directly contribute to the weakening and eventual rupture of the aorta. This structural vulnerability makes the circulatory system highly susceptible to sudden increases in blood pressure.
Factors Driving Cardiovascular Stress
The single largest factor contributing to cardiovascular failure in commercial turkeys is the intense genetic selection for rapid growth and high muscle yield. This accelerated growth rate places unsustainable metabolic demands on the circulatory and respiratory systems, which cannot develop fast enough to keep pace with the massive body size. Turkeys today reach market weight in approximately half the time it took for a bird in the mid-1960s, creating a biological imbalance that underlies most cardiac issues.
Beyond genetics, environmental factors can act as acute stressors that trigger a fatal event in a predisposed bird. Sudden noises, rough handling, or excitement can lead to a rapid spike in blood pressure, which a weakened aorta cannot withstand, resulting in rupture. Furthermore, poor ventilation in brooding houses can lead to low oxygen levels (hypoxia) and increased carbon dioxide, which increase the incidence of Round Heart Disease.
Dietary composition also plays a role in exacerbating cardiovascular stress. High-energy feed formulations, designed to maximize weight gain, contribute to systemic hypertension, which adds strain to the heart and arteries. The copper deficiency, which impairs the structural strength of the aorta, highlights the importance of specific nutritional balance.
Mitigating Cardiac Risk in Turkeys
Poultry management strategies focus on counteracting the effects of the rapid growth rate to allow the cardiovascular system time to mature. Feed restriction is one of the most effective measures, involving carefully controlled feeding schedules during the rapid growth phase, typically from 7 to 15 weeks. By slowing the weight gain, the strain on the heart is reduced, which decreases the overall incidence of Sudden Death Syndrome and Aortic Rupture.
Nutritional adjustments are also implemented to address specific vulnerabilities in the vascular system. Ensuring that the diet contains adequate levels of essential minerals like copper is a preventive step that helps maintain the structural integrity of the arterial walls.
Environmental controls are used to minimize acute stress and respiratory challenges. Reducing sudden noises and ensuring calm handling practices lowers the risk of blood pressure spikes that can trigger an aortic rupture. Maintaining optimal air quality and temperature, particularly by providing enhanced ventilation, helps prevent the low-oxygen conditions associated with increased rates of Spontaneous Turkey Cardiomyopathy.