Symptom Identification and Prevention and Treatment Methods for Necrotic Enteritis
Necrotic Enteritis
Overview
Necrotic enteritis, also known as enterotoxemia, is an acute infectious disease caused by Clostridium perfringens. It mainly manifests as affected chickens passing black droppings or droppings mixed with blood, and dead chickens are characterized by necrosis of the mucosa of the posterior segment of the small intestine.
The occurrence of this disease usually has obvious predisposing factors, such as high flock density and poor ventilation; sudden changes in feed and low protein content in the feed; unreasonable and frequent use of antibacterial drugs, leading to intestinal flora disturbance and decreased digestive function; and it is more likely to be induced after coccidiosis occurs. This disease occurs more frequently in chickens raised on litter, and more frequently in starter and grower chickens. In broilers, the disease is mostly seen at 2 to 8 weeks of age. It can occur in all four seasons, but occurs more frequently in humid seasons when coccidiosis is prone to occur. Because there are many factors that induce this disease, that is, it is caused by comprehensive factors, some people call it "intestinal toxin syndrome." The name "intestinal toxin syndrome" first appeared in technical promotion materials of a veterinary drug manufacturing enterprise in Shandong. This disease name "intestinal toxin syndrome" has now been widely accepted among the public, and because of its diverse causes, it may be more readily accepted by grassroots breeders or veterinarians than the disease name "necrotic enteritis." Nevertheless, the disease name "intestinal toxin syndrome" has not yet been recognized by the national authoritative veterinary authorities and still cannot be considered officially respectable.
Clinical Symptoms
This disease often occurs suddenly, and affected chickens often die suddenly without obvious symptoms. In cases with a slightly longer course, affected chickens may show depression, rough and disordered feathers, and poor appetite or complete loss of appetite. The droppings are abnormal, containing incompletely digested feed particles (undigested feed), so they appear light yellow, mixed with blood, and shed intestinal mucosa may be seen, appearing in segmented pieces; when mixed with blood, they resemble earthworms. Under normal circumstances, the morbidity and mortality of this disease are not high, and if treated promptly, it subsides within 1 week. However, if complicated by viral diseases or colibacillosis, mortality increases significantly.
Necropsy Changes
After opening the abdominal cavity of a fresh dead chicken, a putrid corpse odor rarely seen in general diseases can be smelled. The most characteristic changes are in the intestinal tract, especially in the middle and posterior segments of the small intestine. The intestinal surface appears dirty gray-black or dirty black-green, the intestinal lumen is distended with gas, reaching 2 to 3 times that of normal intestines, and the intestinal wall is thickened. The contents of the intestinal lumen are liquid, foamy, and blood-like or black-green. The intestinal wall is congested, sometimes with hemorrhagic spots, and the mucosa is necrotic, showing bran-like necrotic foci of varying size and shape; some form pseudomembranes that are easy to peel off. Other organs are mostly congested with no specific changes, and it has been reported that widespread degenerative necrosis can be seen in the liver.
Diagnosis
A preliminary diagnosis can be made based on epidemiological characteristics and characteristic pathological changes. Confirmation of this disease mainly relies on microscopic examination of smears from diseased material and isolation and identification of the pathogen. From freshly dead chickens, scrapings of intestinal mucosa or liver impression smears can be taken, subjected to Gram staining, and under the microscope large numbers of uniform Gram-positive, short, thick, large bacilli with blunt rounded ends can be seen, arranged singly or in pairs, staining evenly, and possessing capsules. In diagnosis, attention should be paid to distinguishing it from undigested feed caused by problems with feed ingredients and from ulcerative enteritis.
Prevention and Treatment Measures
Prevention of this disease mainly involves strengthening feeding management, improving the disease resistance of chickens, taking effective measures to reduce the effects of various stress factors, and doing a good job in preventing other diseases. For chickens raised on litter, controlling the occurrence of coccidiosis is of great significance for preventing this disease, especially controlling coccidiosis in broilers raised on litter on the ground.
It is worth noting that during treatment, improving chicken house hygiene conditions, reducing density, strengthening ventilation, and doing a good job in feeding management are very important for rapidly controlling this disease.
Necrotic enteritis, also known as enterotoxemia, is an acute infectious disease caused by Clostridium perfringens. It mainly manifests as affected chickens passing black droppings or droppings mixed with blood, and dead chickens are characterized by necrosis of the mucosa of the posterior segment of the small intestine.
The occurrence of this disease usually has obvious predisposing factors, such as high flock density and poor ventilation; sudden changes in feed and low protein content in the feed; unreasonable and frequent use of antibacterial drugs, leading to intestinal flora disturbance and decreased digestive function; and it is more likely to be induced after coccidiosis occurs. This disease occurs more frequently in chickens raised on litter, and more frequently in starter and grower chickens. In broilers, the disease is mostly seen at 2 to 8 weeks of age. It can occur in all four seasons, but occurs more frequently in humid seasons when coccidiosis is prone to occur. Because there are many factors that induce this disease, that is, it is caused by comprehensive factors, some people call it "intestinal toxin syndrome." The name "intestinal toxin syndrome" first appeared in technical promotion materials of a veterinary drug manufacturing enterprise in Shandong. This disease name "intestinal toxin syndrome" has now been widely accepted among the public, and because of its diverse causes, it may be more readily accepted by grassroots breeders or veterinarians than the disease name "necrotic enteritis." Nevertheless, the disease name "intestinal toxin syndrome" has not yet been recognized by the national authoritative veterinary authorities and still cannot be considered officially respectable.
Clinical Symptoms
This disease often occurs suddenly, and affected chickens often die suddenly without obvious symptoms. In cases with a slightly longer course, affected chickens may show depression, rough and disordered feathers, and poor appetite or complete loss of appetite. The droppings are abnormal, containing incompletely digested feed particles (undigested feed), so they appear light yellow, mixed with blood, and shed intestinal mucosa may be seen, appearing in segmented pieces; when mixed with blood, they resemble earthworms. Under normal circumstances, the morbidity and mortality of this disease are not high, and if treated promptly, it subsides within 1 week. However, if complicated by viral diseases or colibacillosis, mortality increases significantly.
Necropsy Changes
After opening the abdominal cavity of a fresh dead chicken, a putrid corpse odor rarely seen in general diseases can be smelled. The most characteristic changes are in the intestinal tract, especially in the middle and posterior segments of the small intestine. The intestinal surface appears dirty gray-black or dirty black-green, the intestinal lumen is distended with gas, reaching 2 to 3 times that of normal intestines, and the intestinal wall is thickened. The contents of the intestinal lumen are liquid, foamy, and blood-like or black-green. The intestinal wall is congested, sometimes with hemorrhagic spots, and the mucosa is necrotic, showing bran-like necrotic foci of varying size and shape; some form pseudomembranes that are easy to peel off. Other organs are mostly congested with no specific changes, and it has been reported that widespread degenerative necrosis can be seen in the liver.
Diagnosis
A preliminary diagnosis can be made based on epidemiological characteristics and characteristic pathological changes. Confirmation of this disease mainly relies on microscopic examination of smears from diseased material and isolation and identification of the pathogen. From freshly dead chickens, scrapings of intestinal mucosa or liver impression smears can be taken, subjected to Gram staining, and under the microscope large numbers of uniform Gram-positive, short, thick, large bacilli with blunt rounded ends can be seen, arranged singly or in pairs, staining evenly, and possessing capsules. In diagnosis, attention should be paid to distinguishing it from undigested feed caused by problems with feed ingredients and from ulcerative enteritis.
Prevention and Treatment Measures
Prevention of this disease mainly involves strengthening feeding management, improving the disease resistance of chickens, taking effective measures to reduce the effects of various stress factors, and doing a good job in preventing other diseases. For chickens raised on litter, controlling the occurrence of coccidiosis is of great significance for preventing this disease, especially controlling coccidiosis in broilers raised on litter on the ground.
It is worth noting that during treatment, improving chicken house hygiene conditions, reducing density, strengthening ventilation, and doing a good job in feeding management are very important for rapidly controlling this disease.