What are the symptoms of porcine proliferative enteropathy? Detailed explanation of prevention and treatment methods
Porcine proliferative enteropathy, also known as proliferative enteritis, is a common intestinal infectious disease in growing and finishing pigs. Other names include necrotic enteritis, proliferative hemorrhagic enteropathy, porcine ileitis, terminal ileitis, and porcine intestinal adenomatosis. The clinical manifestations of the disease are mainly intermittent diarrhea, decreased appetite, and stunted growth. Growing pigs and replacement gilts sometimes have bloody diarrhea and sudden death. The characteristic finding on necropsy is thickening of the mucosa of the small intestine and ileum. The histopathological change is characterized by adenomatoid proliferation of immature intestinal cells within the crypts of the ileum and colon. The disease is endemic in various parts of the world.
Pathogen
The pathogen causing porcine proliferative enteropathy is Lawsonia intracellularis, which was also formerly called ileal symbiote. It is an obligate anaerobic bacterium of intestinal cells that cannot grow in cell-free culture media and can only grow on intestinal cell lines from mice, pigs, or humans. It is Gram-negative and has no flagella or cilia.
Epidemiology
Diseased pigs and carrier pigs are the source of infection for this disease.
The feces of infected pigs contain necrotic sloughed intestinal wall cells and contain large amounts of the pathogen. The pathogen is excreted from the body with the feces, contaminating the external environment, and is transmitted through the digestive tract via feed, drinking water, and other routes. Adult pigs are more susceptible, and generally pigs under 2 months of age and over 1 year of age are less likely to develop the disease.
The occurrence of this disease is related to various factors such as the external environment. Sudden climate changes, long-distance transport, excessively high stocking density, feed changes, stress from mixing or moving pens, and improper use of antibiotic additives can all serve as triggers for this disease. In addition, birds and rodents also play an important role in the transmission of this disease.
Pathogenesis
The pathogen mainly invades the ileal mucosa, causing thickening of the inner mucosal layer of the ileum. The first site of infection is the intestinal crypt cells. The epithelial cells infected with the bacteria cannot mature and continue to undergo mitosis, resulting in marked proliferation, which is the formation of porcine proliferative enteropathy.
On the basis of cellular proliferation, due to the body's compensatory and reparative responses, lesions overlap. As the surface fibrotic reaction extends and develops in depth, the inflammatory changes coalesce into necrosis, forming the lesions of necrotic enteritis. These lesions of the intestinal mucosa hinder nutrient absorption, leading to weight loss and decreased feed conversion rate.