Exudative diathesis is a nutritional disease that impacts young, rapidly growing poultry, most notably chicks. Arising from a dietary deficiency, the disease is characterized by systemic fluid leakage into the subcutaneous tissues. This condition primarily affects birds between one and five weeks of age and is linked to the feed provided during these early growth stages.
Clinical Signs and Symptoms
The most prominent clinical sign of exudative diathesis is a severe edema, which is the accumulation of fluid beneath the skin. This swelling is commonly found on the breast, abdomen, and the inner surfaces of the thighs and wings. The affected skin can develop a noticeable greenish-blue discoloration as a result of subcutaneous hemorrhages and the subsequent breakdown of hemoglobin in the trapped fluid.
This subcutaneous fluid often gives the skin a distinct, jelly-like texture upon touch. Affected chicks display signs of depression and listlessness, often appearing unthrifty with ruffled feathers. Their reluctance to move is apparent, and they may have difficulty walking or stand with their legs spread far apart due to the discomfort and swelling. In some cases, large scabs may form over areas that have been bruised due to the fragility of their tissues.
The Role of Vitamin E and Selenium
The underlying cause of exudative diathesis is a dietary deficiency in both Vitamin E and the trace mineral selenium. Vitamin E is a primary fat-soluble antioxidant that protects cell membranes from oxidative damage caused by free radicals. This protection is particularly important for the endothelial cells that line blood vessels, maintaining their integrity.
Selenium works in concert with Vitamin E to mitigate oxidative stress. It is a component of the enzyme glutathione peroxidase, which neutralizes harmful peroxide molecules within the cell. The relationship between Vitamin E and selenium is synergistic; they support one another in their antioxidant functions, so a deficiency in one can increase the demand for the other.
When both of these micronutrients are deficient, capillaries become fragile and abnormally permeable. This allows protein-rich plasma to leak out of the blood vessels and accumulate in the subcutaneous space, leading to edema. The condition can be worsened by diets high in polyunsaturated fatty acids (PUFAs), which increase the requirement for Vitamin E to prevent oxidative damage.
Management and Prevention Through Diet
Treating an affected flock involves the prompt administration of the deficient nutrients. Supplementing drinking water with Vitamin E and selenium is an effective method for rapid absorption and can lead to the reversal of symptoms if the condition is not too advanced. A single oral dose of Vitamin E can be sufficient to cause remission in chicks if the disease is caught early. For extensive skin lesions, broad-spectrum antibiotics may be used to manage secondary bacterial infections.
Prevention is centered on formulating nutritionally complete feeds. Poultry diets should contain adequate levels of both Vitamin E and selenium, especially for young, growing birds. Feeds should contain at least 0.3 parts per million of total dietary selenium. Using high-quality, stabilized fats and commercial antioxidants in feed can prevent the rancidity that exacerbates the deficiency.
Feed manufacturers often use stable, microencapsulated forms of Vitamin E to ensure its potency is not lost during storage. Properly formulated feeds maintain their nutritional value for about two months. Careful attention to the dietary balance of these nutrients is the most reliable strategy to prevent outbreaks.
Related Vitamin E Deficiency Diseases
A deficiency in Vitamin E can manifest as other distinct syndromes in poultry besides exudative diathesis. One such condition is encephalomalacia, often referred to as “crazy chick disease.” This neurological disorder is characterized by ataxia, loss of balance, and uncontrolled movements, resulting from hemorrhage and edema in the cerebellum. It occurs when diets are low in Vitamin E, especially in the presence of unstable, unsaturated fats.
Another related condition is nutritional muscular dystrophy. This disease affects the muscle tissues, leading to the development of white or yellowish streaks in the breast, leg, gizzard, and heart muscles. While it can be caused by a Vitamin E deficiency, it is more specifically linked to a combined deficiency of Vitamin E and sulfur-containing amino acids. Though they share a common nutritional origin, these diseases are distinct from exudative diathesis as they impact different systems within the bird’s body.