What are the diagnostic measures for common infectious diseases in pigs?

In late spring and early summer, as the seasons change, the weather is unpredictable, various epidemic diseases occur frequently, and pigs are susceptible to epidemic diseases.

In pig production, pig diseases characterized by typical digestive tract symptoms such as diarrhea are often encountered. The causes include viral diseases, bacterial diseases, and parasitic diseases. These pig diseases all have symptoms of diarrhea and are prone to misdiagnosis, so scientific differentiation and timely confirmation are particularly important.

Yellow scour of newborn piglets

Yellow scour of newborn piglets is an acute, fatal disease caused by pathogenic Escherichia coli. Affected pigs have diarrhea and pass yellow serous thin feces containing small curd flakes, and quickly become emaciated and die in a coma. The gastrointestinal tract is distended, with large amounts of yellow liquid contents and gas, the intestinal mucosa shows acute catarrhal inflammation, and the small intestinal wall becomes thin. It occurs most easily in 1- to 3-day-old piglets, and some piglets develop the disease within 12 hours after birth, with high morbidity and mortality.

White scour of piglets

White scour of piglets is an acute intestinal infectious disease caused by pathogenic Escherichia coli. The feces of affected pigs are milky white or grayish white, serous or pasty, foul-smelling and sticky, and the intestinal mucosa shows catarrhal inflammatory lesions. It mostly occurs in 10- to 30-day-old piglets, with moderate morbidity and low mortality.

Red scour of piglets

Red scour of piglets is a highly fatal enterotoxemia caused by Clostridium perfringens type C, with bloody diarrhea, a short course, high mortality, and diffuse hemorrhage or necrotic changes in the posterior segment of the small intestine. Affected pigs pass bloody thin feces containing fragments of necrotic tissue. The jejunum is dark red, the mesenteric lymph nodes are bright red, there are small petechial hemorrhages on the edge of the spleen, and the kidneys are grayish white. It mainly affects 1- to 3-day-old piglets, and piglets over 1 week old rarely develop the disease, with high morbidity and low mortality.

Swine dysentery

Swine dysentery is an intestinal infectious disease caused by pathogenic Brachyspira hyodysenteriae. The colonic mucosa of affected pigs develops catarrhal hemorrhagic inflammation and fibrinous necrotizing inflammation, with mucous or mucohemorrhagic diarrhea. Affected pigs have reduced appetite, and the feces become soft with strip-like mucus on the surface, after which the feces become yellow and soft or watery, until the feces are full of blood and mucus. The colonic mucosa is swollen and covered with mucus and fibrin with blood clots, and the contents are soft to thin and mixed with mucus, blood, and tissue fragments. Pigs of all ages and breeds are susceptible, but it occurs more often in 7- to 12-week-old piglets. The disease has no seasonality in its occurrence and lasts a long time.

Transmissible gastroenteritis of swine

Transmissible gastroenteritis of swine is a highly contagious intestinal disease caused by porcine transmissible gastroenteritis virus (a coronavirus). Affected pigs vomit, have severe diarrhea, and become dehydrated. Piglet feces are yellow, green, or white and may contain undigested curd lumps. Adult pigs have vomiting and grayish-brown watery diarrhea. The mucosa of the gastric fundus is congested and hemorrhagic, the mesentery is congested, the lymph nodes are swollen, and the intestinal wall becomes thin and translucent. Mortality is high in piglets within 10 days of age, low in pigs over 5 weeks of age, and adult pigs almost never die. It generally occurs in winter and spring, with the peak incidence in January and February.

Porcine epidemic diarrhea

Porcine epidemic diarrhea is an acute contagious intestinal infectious disease caused by porcine epidemic diarrhea virus (a coronavirus). Affected pigs vomit, have diarrhea, and become dehydrated. Affected pigs have watery diarrhea, severe dehydration, depression, and reduced appetite. The small intestine is dilated and filled with yellow liquid, the mesentery is congested, the mesenteric lymph nodes are edematous, and the small intestinal villi are shortened. Pigs of all ages are infected, and morbidity is high in suckling piglets, growing pigs, or finishing pigs. The disease mostly occurs in cold seasons, with the highest occurrence in December and January of the following year.

Paratyphoid of piglets

Paratyphoid of piglets is a disease caused by Salmonella, with clinical symptoms such as septicemia, enteritis, and abortion in pregnant sows. The skin at the base of the ears, on the chest, under the abdomen, and on the hindquarters of affected pigs is purplish red, the feces are foul-smelling and pale yellow or yellow-green, and are mixed with blood, necrotic tissue, or fibrinous flakes. The spleen is enlarged, relatively hard, and dark purplish red, the systemic lymph nodes are congested and swollen, and the mesenteric lymph nodes are enlarged and cord-like. It often occurs in piglets under 6 months of age, and occurs more often in those 1 to 4 months old. The disease can occur in all four seasons, and occurs more often in rainy and humid seasons.