Common pathogenic diarrhea in pigs and its prevention and treatment

There are many causes of diarrhea in pigs in production, such as malnutrition, improper feeding and management, infectious diseases, internal diseases, parasitic diseases and so on. This paper analyzes the mechanism of pathogenic diarrhea in pigs and puts forward prevention and control countermeasures for readers' reference.

1 Classification of common pathogenic diarrhea in pigs

1.1 viral diarrhea

1.1.1 transmissible gastroenteritis is an acute, contagious intestinal infectious disease caused by transmissible gastroenteritis virus of the coronavirus family. Pigs of all ages can be infected, and big pigs rarely die, but the mortality rate of suckling piglets can reach 10% to 100%. The disease is prevalent in local areas and has obvious seasonality, with the highest incidence in winter and spring. The sick piglets suddenly developed vomiting, followed by acute watery diarrhea, elevated body temperature, mental fatigue and anorexia. Feces are white at first, then turn yellowish green, often mixed with undigested milk clots and air bubbles, pH test is acidic, smelly. Diseased pigs are rapidly dehydrated, emaciated, severely thirsty, loss of appetite or abstinence, and usually die after 2-7 days.

1.1.2 Porcine epidemic diarrhea is a highly contagious disease caused by porcine epidemic diarrhea virus of the coronavirus family. It often occurs in winter, especially in December and January. Pigs of different ages could be infected, and only vomiting and anorexia occurred in adult pigs, which could be quieted down naturally after 4-5 weeks of disease. The typical symptoms of nursing piglets are vomiting and watery diarrhea, loss of appetite, depression, rapid weight loss, dehydration and death in severe cases.

1.1.3 Rotavirus belongs to the genus Rotavirus of Reoviridae. It is highly resistant to various physical and chemical factors and is still contagious at room temperature for 7 months. Stress factors such as cold, humidity and poor sanitary conditions can promote the occurrence and development of the disease, so the disease is more common in autumn, winter and early spring, and often occurs in piglets about 10 days old, and sometimes occurs in pigs before and after weaning. At the beginning of the illness, mental malaise, loss of appetite, unwilling to move, and often vomiting. Then diarrhea occurred quickly, the feces were watery or paste, the color was yellow, white or dark, and dehydration occurred after 3-7 days. The lesions were mainly limited to the digestive tract, the stomach of piglets was full of milk clots or milk, the wall of small intestine was thin and translucent, and the contents were liquid, grayish yellow or grayish black. Sometimes the small intestine bleeds extensively and the mesenteric lymph nodes are enlarged.

1.2 bacterial diarrhea

1.2.1 diarrhea caused by Escherichia coli in pigs can be divided into yellow dysentery and white dysentery according to the age of pigs.

1.2.1.1 Yellow dysentery of piglets, also known as early-onset colibacillosis, is an acute and highly fatal disease of newborn piglets, characterized by severe watery diarrhea and rapid death. Generally, infection occurs 1-7 days after birth, suddenly diarrhea, discharge of water-like feces, yellow or grayish yellow, mixed with small bubbles and fishy smell, and then diarrhea becomes more and more serious. The sick pig was thirsty and dehydrated, but there was no vomiting, and finally died in a coma. The lesion is acute catarrhal inflammation of the intestinal tract, of which the duodenum is the most serious.

1.2.1.2 White dysentery of piglets, also known as delayed colibacillosis, is a common disease in 10-30-day-old piglets. The pathogen often exists in the intestines of pigs and does not cause disease under normal circumstances. When there is a sudden change in temperature, sow milk is too thin or too strong and other adverse stress, piglets' resistance decreases and sometimes occurs. The disease is highly contagious and one piglet in a litter has diarrhea. If measures are not taken in time, it will soon infect the whole group. Its typical symptoms are: White, paste, fishy stool, fecal pollution around the anus, like to drill haystacks, no vomiting, body temperature is generally not high, slowly lose weight and die. The case fatality rate is directly related to feeding management and treatment.

1.2.2 Clostridium enteritis is also known as infectious necrotizing enteritis of piglets, commonly known as piglet red dysentery. The pathogen Clostridium welchii type C or Clostridium perfringens type C. Most of the disease occurred in 1-3-day-old newborn piglets with short course of disease and high mortality, while even 4-7-day-old piglets had mild symptoms. Diseased pork chops are red with sticky dung and occasionally vomit.

1.2.3 Porcine dysentery is an intestinal infectious disease caused by a gram-negative bacterium Borrelia pullorum. Both big and small pigs could be infected, but most of them occurred in 2-and 4-day-old piglets. Seasonality is not obvious, slow transmission, long epidemic period, easy recurrence, high incidence, low mortality, normal body temperature, but slightly higher at the beginning of the disease, feces containing a large amount of mucus and blood, often jelly-like. The pathological changes were mainly in the large intestine.

1.2.4 Porcine salmonellosis, also known as piglet paratyphoid, is an intestinal infectious disease of weaned piglets caused by pathogenic salmonella. The main damage to 2-4-month-old pigs, there is no obvious seasonality, showing a regional epidemic. Salmonella is gram-negative bacteria, commonly used disinfectants can kill it in a short time. The body temperature of diseased pigs is slightly higher, showing acute septicemia and severe diarrhea, feces stink, anus, tail, hind legs and other places sticky feces containing blood; chronic patients with repeated diarrhea, feces are yellowish, light green, smelly, skin can appear erythema. Autopsy revealed diffuse sunken irregular ulcers and pseudomembrane in the cecum and colon.

1.3 proliferative enteritis

Also known as ileitis or intestinal adenoma complex. The pathogen is undetermined. The disease mostly occurs in breeding pigs or big pigs weighing about 100 kilograms. The clinical features are long course of disease and black wood tar-like feces. Autopsy showed that the large intestine showed proliferative hemorrhagic enteritis, the mucosa from ileum to cecum showed adenomatous growth and protuberance, and purulent mucus could be extruded when complicated with infection.

1.4 parasitic diarrhea

1.4.1 coccidiosis mostly causes diarrhea in 1-3-week-old piglets, especially in 6-10-day-old piglets. From July to August, the weather is rainy, humid, the temperature changes greatly, and when the pig house is wet, coccidiosis is easy to break out. The infected pigs began to pull yellow-brown to gray paste feces and became watery diarrhea and progressive emaciation after 1-2 days. If concomitant or secondary infection, the fatality rate will increase.

1.4.2 Ascaris lumbricoides is susceptible at the age of 3 ~ 6 months. Except that Ascaris lumbricoides larvae migrate to lungs and other organs with blood flow, resulting in Ascaris pneumonia, adults parasitize in the small intestine, secrete toxins, dyspnea and dysentery in diseased pigs. The pigs suffered from progressive weight loss, growth retardation and growth retardation. Ascaris lumbricoides can be found in the small intestine during autopsy, and catarrhal enteritis, bleeding or ulcers can be seen in severe cases.

2 prevention and treatment of pathogenic diarrhea

The main countermeasure for the prevention and treatment of pathogenic diarrhea is to adhere to the principle of "prevention first, prevention is more important than cure", strengthen feeding management, pay attention to environmental hygiene and disinfection, ensure reasonable feeding density and cool in winter and summer in the enclosure. In addition, it is necessary to develop immunization procedures suitable for this field or the region, and appropriate treatment should be taken once the disease occurs.

2.1 Prevention and treatment of viral diarrhea

At present, there is no specific method for the treatment of viral diseases at home and abroad, so we should adhere to the principle of "prevention is more important than cure" for viral diarrhea. The main countermeasures are as follows:

2.1.1 introduction should not be introduced from epidemic areas or diseased pig farms, but should be self-propagated and self-raised so as not to bring pathogens. If the introduction is necessary, it should be isolated and observed for one month before you can mix with the group.

2.1.2 for porcine transmissible gastroenteritis and rotavirus, it is best to use the attenuated vaccine of transmissible gastroenteritis and rotavirus to intranasally inoculate sows 5-6 weeks and 1 week before parturition. The passive immune protection rate of 3-day-old suckling piglets can reach more than 95%. For pig farms or areas where the disease has occurred, fattening pigs and boars can be vaccinated once again after the arrival of autumn; for porcine epidemic diarrhea, inactivated aluminum hydroxide vaccine can be used for porcine epidemic diarrhea, pregnant sows are vaccinated with 4 ml at 20-30 days before delivery, piglets below 25 kg are vaccinated with 1 ml, pigs with 25 kg and 50 kg are vaccinated with 2 ml, and pigs with more than 50 kg are vaccinated with 4 ml. The inoculation site was Houhai acupoint, and immunity was produced 15 days after inoculation.

2.1.3 there is no specific treatment for viral diarrhea, and symptomatic treatment is mainly adopted for the virus, such as feeding convergent antidiarrheal tannic acid protein, bismuth nitrate and other drugs, and using sulfonamides and antibiotics to prevent secondary bacterial infection. commonly used drugs such as dysentery, sulfamethazine and other drugs have a certain effect, at the same time, it is best to use antiviral drugs, such as amantadine and so on.

2.2 Prevention and treatment of bacterial diarrhea

With the continuous expansion of the scale of pig breeding, pollution is becoming more and more serious, coupled with the improper use of antibiotics and feed additives containing antibiotics, resulting in drug resistance of many bacteria, drug-resistant strains have become the main problem affecting the pig industry. Therefore, comprehensive measures should be taken to prevent and cure porcine bacterial diarrhea, and the common countermeasures are as follows:

2.2.1 prevent the source of infection from entering the pig farm regularly disinfect the pig farm with disinfectant, usually strictly manage, irrelevant personnel are not allowed to enter the pig farm, strictly prevent the introduction of the source of infection. Imported pigs must be isolated and observed to create a good living environment for weaned pigs and eliminate all kinds of stress.

2.2.2 adding microecological agents to inhibit the growth and reproduction of harmful bacteria, adjust the microecological balance in pig intestines, and reduce the occurrence of diarrhea.

2.2.3 the practice of adding appropriate amount of copper, zinc and other trace elements to the feed has proved that adding 250 mg / kg copper and 300 mg / kg zinc oxide to the feed can not only enhance the body resistance, but also has the effect of antibacterial and anti-diarrhea.

2.2.4 after the treatment of the disease, it is best to select the sensitive drugs of the pig farm through the drug sensitivity test. In addition, attention should be paid to the alternate use of drugs to prevent the production of drug-resistant strains.

2.3 Prevention and treatment of parasitic diarrhea

Parasitic diarrhea is mainly related to feeding management and sanitary conditions, so the common countermeasures are as follows:

Strengthen feeding and management, pay attention to the supply of trace elements and vitamins, and improve the resistance of the body. The enclosure is regularly cleaned, kept clean and dry, and feces accumulate to ferment to kill eggs, coccidia oocysts and other pathogenic microorganisms.

Prophylactic deworming with corresponding drugs, such as ivermectin or avermectin, which acts on nematodes in the body. Deworming is carried out once a year in spring and autumn, and the feces discharged within a week after medication should be collected and concentrated for accumulation and fermentation. From July to August, anti-coccidiosis drugs should be added to the feed to control porcine coccidiosis. As coccidia are prone to drug resistance, they must be added in sufficient quantities and pay attention to the rotation of drugs.

Keeping cats, dogs and chickens in pig farms should be prohibited, strict anti-rodent measures should be implemented, and the route of animal transmission should be cut off.