Prevention and Control Methods for Common Intestinal Diseases in Pig Farms

Pig intestinal diseases are numerous and diverse, with complex causes, and they cause great harm to pig production. Here is a brief overview of the types of diseases, causes of onset, and prevention and treatment methods, for reference by pig farms.

Types:

Porcine enterovirus infection Porcine enteroviruses have 6 different serotypes. The ways of acquiring infection are usually: infection of piglets shortly after weaning when maternal antibodies disappear; infection when several litters of piglets are mixed together. Different clinical symptoms are associated with different serotypes, and may present as: polioencephalomyelitis, reproductive disorders, diarrhea, pneumonia and pericarditis, myocarditis, etc. Severely infected piglets may show focal myocardial necrosis.

Rotavirus infection This disease mostly occurs in piglets within 8 weeks of age, with a relatively high mortality rate, reaching up to 50%. Sick pigs are depressed and unwilling to move. In the early stage of the disease, they often vomit after eating, and pass watery or pasty yellow-white or gray-brown feces, often dying within 3 days to 7 days due to dehydration. Necropsy shows the stomach filled with curdled milk, mucosal shedding, and in some sick pigs, small intestinal mucosal congestion or hemorrhage. Currently there are no specific drugs or preventive vaccines. In epidemic areas, newborn piglets should receive colostrum early to obtain the protection of maternal antibodies.

Intestinal adenomatosis complex, also called proliferative enteropathy of pigs, is mostly seen in pigs aged 3 days to 8 days. According to lesion characteristics, it can be divided into 4 types: intestinal adenomatosis, necrotic ileitis, regional ileitis, and proliferative hemorrhagic enteritis. Clinical manifestations include sick pigs being listless, with reduced appetite, severe diarrhea, weight loss, rough coat, and anemia. If the course of the disease is prolonged, black tarry feces will be passed, which gradually becomes lighter afterward; some pigs do not show abnormal feces, but the visible mucosa is pale.

Yersiniosis occurs mostly in summer and winter, and is sporadic. The incubation period in sick pigs is 2 days to 3 days. In the initial stage, body temperature is 40°C to 41°C, appetite is reduced or lost, and there is watery diarrhea. The feces often contain mucus and shed intestinal mucosa. In the later stage, body temperature drops, the skin becomes cyanotic, and the pig becomes emaciated and dehydrated. Necropsy shows swelling of solitary lymphoid follicles in the colon and rectum, protruding toward the serosal layer or mucosal layer. The small colon and rectum have ulcerative lesions.

Porcine epidemic diarrhea is caused by coronavirus, and mainly occurs in the cold season of late winter and early spring. At the beginning of the disease, body temperature is normal or slightly elevated, with depression and reduced appetite, and watery, gray-yellow or gray feces with a sour odor, containing undigested food. Older pigs have milder symptoms. Younger pigs are prone to vomiting after eating and pass gruel-like or watery thin feces. Necropsy shows the small intestine is distended, filled with yellow contents, the intestinal wall becomes thinner, and the mesentery shows branching congestion. The younger the piglet, the higher the mortality rate.

Porcine transmissible gastroenteritis Pigs of all ages are susceptible, and it occurs mostly in piglets under 2 weeks of age in late winter or early spring. It spreads very quickly and has a relatively high mortality rate. Piglets often vomit after suckling, and soon develop severe diarrhea, passing watery yellow or gray-white feces. Pigs after weaning have mild symptoms, showing only reduced feeding and diarrhea, with individual pigs vomiting after eating, but the mortality rate is relatively low. Finishing pigs and sows have milder symptoms, manifesting as poor appetite, with individual cases showing vomiting and watery diarrhea. Generally, diarrhea stops after 5 days to 8 days, and the sick pigs recover. Necropsy shows obvious catarrhal inflammation of the gastric fundus and intestinal mucosa, and congestion of mesenteric blood vessels; some affected piglets may develop concurrent pneumonia.

Porcine colibacillosis mainly includes piglet yellow scour, white scour, and piglet edema disease. Yellow scour can occur in piglets within 7 days of birth, and is more common at 1 day to 3 days of age. Some piglets suddenly become ill and die within 12 hours or 3 days after birth. The main symptoms of affected pigs are passing yellow or yellow-white watery thin feces containing curds, reduced or no suckling, dehydration, sunken eyeballs, and rapid emaciation; if not treated in time, they die within one or two days. White scour mostly occurs in piglets from 10 days to 30 days of age. The feces of sick pigs are milky white, pale yellow-green, or gray-white, with a fishy odor, often mixed with mucus and pasty, containing bubbles. If not treated in time, diarrhea worsens, breathing accelerates, walking becomes unsteady, and death occurs in 5 days to 6 days; necropsy shows the colonic contents are paste-like or ointment-like, milky white or gray, and sticky; the small intestinal mucosa has catarrhal inflammatory changes, the intestinal wall becomes thinner, and the mesenteric lymph nodes are mildly swollen. Piglet edema disease is mostly seen in weaned piglets with vigorous growth and development. Sick pigs have eyelid edema and ataxia, and neurological symptoms appear in the later stage.

Porcine treponemal disease, also called swine dysentery or swine bloody dysentery, is an infectious disease caused by Brachyspira hyodysenteriae. It occurs mostly in pigs from 7 weeks to 12 weeks of age. Its characteristics are hemorrhagic large intestinal mucosal lesions, diarrhea, and necrotic inflammation. General disinfectants can kill this pathogen. In the initial stage, the body temperature of sick pigs can reach 40°C to 41°C, and they pass yellow or gray soft feces. In the later stage, the feces become watery, often mixed with blood, mucus, and mucosa, making the feces oily or gelatinous. Sick pigs arch their backs and tuck their bellies, rapidly become emaciated, have reduced appetite, increased thirst, and later die from malnutrition and dehydration. Necropsy shows catarrhal hemorrhagic enteritis in the large intestine; the intestinal wall is swollen and thickened, the mucosa is congested and hemorrhagic, and the intestinal contents are thin, mixed with blood and dark red; in some cases, necrotic inflammation appears, covered with caseous pseudomembrane. For clinical diagnosis, fresh feces are generally collected, smeared, stained with crystal violet, and examined under a microscope. More than 5 slender, curved treponemes with pointed ends can be seen per field of view. If fresh diseased feces are examined under dark-field microscopy, large spirochetes with lively movement can be seen.