The Harm and Prevention and Control Methods of Pig Digestive Tract Diseases in Autumn and Winter
The Harm and Prevention and Control of Pig Digestive Tract Diseases in Autumn and Winter
1 Bacterial diarrhea
1.1 Piglet red dysentery: The pathogen is Clostridium perfringens type C. It can cause highly lethal enterotoxemia in piglets within 1 week of age, especially piglets aged 1-3 days, which are the main targets of this pathogen. Clinical manifestations include discharge of pink bloody stool, sometimes mixed with small bubbles; affected pigs refuse to suckle, are sensitive to cold environments, and tremble all over. The disease has a rapid onset, short course, and high mortality rate. The main lesion sites are the ileum and jejunum, which appear dark red on external examination. Necropsy reveals a large amount of red ascites accumulated in the abdominal cavity, the intestines filled with bloody contents, necrosis of jejunal villi, extensive hemorrhage of the intestinal mucosa and submucosa, and bright red mesenteric lymph nodes.
1.2 Piglet yellow-white dysentery: The pathogen is pathogenic Escherichia coli. Yellow dysentery is also called early-onset colibacillosis because it occurs frequently in piglets within 1 week of age. The main clinical manifestation of yellow dysentery is discharge of pasty thin feces, yellow or yellowish-white in color, containing curd flakes, small bubbles, and mucus. The course is short, with a relatively high mortality rate. Dead piglets are severely dehydrated, with edema observable under the skin of the neck and abdomen, purple-red skin under the abdomen, and red anus and vulva; necropsy reveals edema of the gastric mucosa, dark red gastric fundus, and the stomach filled with yellow curd blocks with a sour odor; the distended intestines contain a large amount of yellow liquid contents and gas, and the intestinal mucosa, especially the duodenum, shows acute catarrhal inflammatory changes; petechial hemorrhage of the mesenteric lymph nodes. White dysentery occurs mostly in piglets aged 10-30 days, so it is also called late-onset colibacillosis. Clinical manifestations include discharge of milky white, pale yellow, or grayish-white viscous feces with a special fishy odor. Usually, diarrhea occurs suddenly when the affected pig's body temperature and appetite are normal; the course is long, the mortality rate is low, and dead pigs are pale and emaciated. Necropsy similarly reveals a large amount of curd blocks in the stomach and yellowish-white or grayish-white viscous thin feces in the intestinal cavity. The small intestinal mucosa shows catarrhal inflammatory changes, the intestinal wall is thin and transparent, and the mesenteric lymph nodes are mildly red and swollen.
1.3 Piglet paratyphoid: The pathogen is Salmonella, which mainly infects pigs aged 1-4 months. It occurs more frequently in the low-temperature and rainy winter and spring seasons, and presents as endemic or sporadic. Mixed infections with swine fever and swine enzootic pneumonia are relatively common. In terms of clinical symptoms, the acute type manifests as constipation first, followed by diarrhea, with foul-smelling feces; the chronic type manifests as constipation first, followed by persistent or intermittent diarrhea, with feces mixed with blood, necrotic tissue, and cellulose fragments, yellow or yellow-green in color, with a foul odor. Necropsy reveals necrotizing enteritis in the affected pig, sometimes involving the cecum, colon, and posterior segment of the ileum, with thickening of the intestinal wall and a layer of diffuse necrotic material covering the submucosa. Lymph nodes are swollen, and there are necrotic foci in the liver and kidneys.
1.4 Swine dysentery: The pathogen is Brachyspira hyodysenteriae. This disease is a highly contagious mucoid, hemorrhagic diarrheal disease, and other microorganisms in the intestine also participate in the pathogenicity of this bacterium. Pigs of all ages can be infected, but the main targets are piglets aged 6-12 weeks. Clinical manifestations include first passing yellow or gray soft stool, followed by watery feces, with blood, mucus, and mucosa mixed in the feces. The main lesions are catarrhal hemorrhagic inflammation of the large intestinal mucosa, with the ileocecal valve as a clear demarcation, and the large intestinal mucosa swollen and covered with mucus and cellulose with blood clots.
2 Viral diarrhea
2.1 Porcine transmissible gastroenteritis: It is a highly contact intestinal infectious disease caused by porcine transmissible gastroenteritis virus. It can infect pigs of all ages; the older the affected pig, the lower the mortality rate. For piglets within 1 week of age, from the appearance of clinical symptoms to death generally takes only 2-7 days, and the mortality rate can reach as high as 100%. After 3-7 days of diarrhea, adult pigs can gradually recover, but they remain physically weak for a period and may also become stunted pigs. Affected piglets show severe watery diarrhea, vomiting, and dehydration. The clinical symptoms of finishing pigs, sows, and boars vary in severity. Common symptoms include anorexia, with occasional vomiting, and severely affected pigs discharge watery feces in a projectile manner. Lactating sows are severely affected after infection, with elevated body temperature, accompanied by anorexia, vomiting, and diarrhea, causing cessation of lactation, which is another factor causing high piglet mortality. The stomach and small intestine are the main lesion sites of this disease. The stomach is filled with milk curds, and the gastric fundus mucosa is congested. The small intestine is congested, the intestinal wall becomes thin and shiny, and the interior is filled with yellow-green or grayish-white liquid material containing foam and undigested milk curds. The mesenteric lymph nodes are congested and edematous.
2.2 Porcine epidemic diarrhea: It is an acute, highly contact infectious disease caused by porcine epidemic diarrhea virus. Winter is the season of high incidence, and suckling piglets are most severely affected, with a mortality rate reaching 80%-100%[6]. The incidence rate in growing pigs and finishing pigs is also very high, but the resulting mortality rate is somewhat lower. Mixed infection with transmissible gastroenteritis is very common. The main clinical symptoms of piglets are difficult to distinguish from transmissible gastroenteritis, all presenting as vomiting, dehydration, and watery diarrhea. Lesions appear only in the small intestine, with intestinal dilation, thinning of the intestinal wall, the interior filled with yellow liquid, and atrophy of small intestinal villi; mesenteric congestion, and mesenteric lymph nodes congested and edematous.
2.3 Porcine rotavirus infection: It is caused by rotavirus, an important intestinal pathogen of various newborn animals including piglets. Late autumn, winter, and early spring are seasons of high incidence of this disease, presenting as endemic. Pigs of all ages can be infected by this virus, and the infection rate is as high as 90%-100%. Adult pigs in most epidemic areas can acquire immunity after infection. Piglets under 8 weeks of age are most severely affected; the younger the piglet, the higher the incidence rate and the higher the mortality rate. The lesions of piglets infected with rotavirus are mainly limited to the digestive tract; gastric activity is sluggish and the interior is filled with curd blocks and milk, the small intestinal wall becomes thin and semi-transparent, the intestinal contents are serous or thin as water, intestinal villi atrophy, mesenteric lymph nodes are edematous, and the gallbladder is enlarged.
3 Parasitic diarrhea
3.1 Porcine coccidiosis: It is a protozoan disease caused by Isospora suis and certain Eimeria coccidia parasitizing the epithelial cells of the small intestine of piglets. Piglets aged 8-15 days are susceptible, and the seasons with high incidence are summer and autumn. Clinical symptoms of affected pigs are mostly discharge of yellow or yellowish-white feces, initially viscous, and after 1-2 d watery thin feces; death or weakness, emaciation, and stunted growth of affected pigs are often due to dehydration. Foreign material mostly covers the jejunal and ileal mucosa of dead pigs, with atrophy and shedding of intestinal villi.
3.2 Nematode disease: The nematodes parasitizing the pig digestive tract include: Trichuris, Ascaris suum, whipworm, nodular worm, Strongyloides, hookworm, Oesophagostomum, etc. Piglets are the main targets, accompanied by abdominal pain, intractable diarrhea, and mucus, pus, and bloody dysentery in the feces. This disease can occur in both free-range and large-scale pig herds.
3.3 Trematode disease: Fasciolopsis buski is the main trematode causing diarrhea in pigs, and humans can also be infected by this parasite. Fasciolopsis buski parasitizes in the small intestine of pigs, causing inflammation of the intestinal mucosa, leading to anemia, emaciation, and diarrhea.
3.4 Toxoplasmosis: As one of the main diseases of pigs, it is a zoonotic protozoan disease. The main symptoms of affected pigs include: initial constipation with mucus on the surface of fecal pellets, persistent high fever (40.5-42°C), complete loss of appetite, and in the later stage foul-smelling diarrhea, with cyanosis visible on the skin of the limbs, underside of the abdomen, ears, etc.
4 Non-infectious causes
4.1 Environmental diarrhea
In autumn and winter, temperatures are low, and piglets under stress are prone to diarrhea syndrome. Factors such as sudden temperature changes, continuous rain, dampness and cold, ventilation and sanitation, and sudden environmental changes that cause stress reactions in the body all become predisposing factors for pig diarrhea. Under low-temperature conditions, growing pigs and medium-large pigs can both produce adverse stress reactions. Nutritional metabolism occurs inside the body, causing functional disorders, while pathological symptoms such as diarrhea or constipation appear externally. Farm staff cannot effectively implement veterinary hygiene system management and biosafety prevention measures, resulting in excessive levels of harmful gases and pathogenic microorganisms, leading to digestive tract diseases.
4.2 Nutritional diarrhea
Long-term deficiency of certain nutrients or improper combination can lead to poor development and abnormal changes (inflammation, necrosis, and shedding) of the gastrointestinal mucosa of pigs; insufficient nutrients in the feed affect the quantity and quality of breast milk. For example, when breast milk is deficient in VB or has excessive protein or lipid content, it can cause gastrointestinal digestive dysfunction, leading to indigestion and diarrhea; protein molecules that have been acted upon by digestive enzymes but not completely decomposed enter the large intestine for fermentation. The final products of fermentation include toxic amines, tyramine, histamine, and putrescine. These substances cause inflammation of the digestive tract, reduce secondary intestinal absorption, and lead to secondary infection; uneven feeding and overeating and drinking cause immediate diarrhea in pigs; accidental ingestion of toxic substances and chemical drugs such as acids, bases, and arsenic can also cause diarrhea.
5 Prevention and control of pig digestive tract diseasesPrevention and control
5.1 Prevention and control of bacterial diarrheaPrevention and control
Due to the abuse of antibiotics in recent years, bacterial drug resistance has gradually increased. In thetreatmentof bacterial diarrhea, relatively sensitive drugs should be selected, and the dosage used should be sufficiently large, and thetreatmentcourse should be sufficiently long. Sulfonamides or antibiotics can be selected fortreatment, such as sulfadimidine, sulfaguanidine, gentamicin, florfenicol, etc. The methods that can be used include oral administration and injection.Treatmentshould adhere to the principle of treating both the sow and piglets, that is, if one pig in the same litter is affected, all piglets in the litter should be treated. While using medication, attention should be paid to improving the environment and sanitation conditions, enhancing nutrition, and promoting the recovery of affected pigs.
5.2 Prevention and control of viral diarrheaPrevention and control
Since there is no specific drug for thetreatmentof viral diarrhea, it can only be prevented through vaccine immunization. Immunization is an important measure to control the occurrence of infectious diseases. Currently, the vaccines used for thetreatmentof viral diarrhea mainly include the porcine transmissible gastroenteritis and porcine epidemic diarrhea bivalent inactivated vaccine, the porcine transmissible gastroenteritis and porcine epidemic diarrhea bivalent live vaccine, and the porcine transmissible gastroenteritis, porcine epidemic diarrhea, and rotavirus trivalent live vaccine. Since live vaccines can both stimulate the body to produce humoral immunity and stimulate the body to produce cellular immunity, and can produce antibodies more quickly, the use of live vaccines is more effective than inactivated vaccines. The use and storage of vaccines should be strictly carried out according to the instructions. In practical application, corresponding immunization measures can be formulated in combination with the local epidemic situation and the actual situation of the pig farm. At the same time, a scientific immunization program should be adopted according to the health status of the body and the maternal antibody status of young pigs. If conditions permit, antibody monitoring can be carried out; if not, the immunization program can be determined based on the successful experience of pig farms under the same conditions.
5.3 Prevention and control of parasitic diarrheaPrevention and control
Due to the characteristic that coccidia easily develop drug resistance,treatmentor prevention should involve planned alternating or combined use of anticoccidial drugs.Treatmentdrugs are mostly oral sulfonamides, coccidiostats, or diclazuril. To achieve the besttreatmenteffect, earlytreatmentis essential. Nematodetreatmentand prevention drugs include levamisole, albendazole, ivermectin, etc. Toxoplasmatreatmentuses sulfonamide drugs, such as sulfamethoxypyridazine, sulfadimethoxine, compound sulfamethoxazole, etc. To achieve preventive effects, it is necessary to ensure good environmental sanitation in and around the pig farm, strictly prohibit keeping cats, and guard against oocyst contamination of feed and drinking water. Raw meat scraps are prohibited in pig feeding, and swill should be cooked before feeding. Trematodetreatmentdrugs include praziquantel, bithionol, nitrothiocyanamine, etc.
5.4 Comprehensive prevention and control
Strengthen nutrition: Provide complete-price feed to the pig herd, ensure balanced nutritional supply for the pig herd, strictly prevent deficiency of vitamins and trace elements, and by improving the feed quality level of the pig herd, enhance the resistance of the pig body, thereby resisting pathogens, especially enhancing defense against intestinal pathogens, and reducing the possibility of outbreaks of pig intestinal diseases. Provide sufficient clean and hygienic water. Strictly prevent pigs from drinking contaminated and icy cold water sources.
Keep warm: Appropriate temperature can not only ensure that piglets obtain better resistance, but also prevent newborn piglets from being crushed to death because they are afraid of the cold and huddle close to the sow. Generally, the temperature for newborn piglets aged 1-3 days should reach 30-35°C, 27-30°C for 4-7 days of age, and 22-26°C for 8-30 days of age. The main methods for keeping piglets warm include: heat preservation boxes, heat lamps, adding heating equipment, etc. Close doors and windows, block gaps, prevent external cold wind from entering the pig house, and try not to use water to wash pig pens in cold seasons.
Disinfection: Disinfection should select appropriate disinfectants and disinfection methods according to the type and characteristics of the pathogen. For disinfection with pigs present, acid-based and aldehyde-based disinfectants can be selected; for empty barn disinfection, alkaline disinfectants can be selected. Moreover, try to choose highly effective disinfectants to achieve better disinfection effects, and ensure sufficient disinfection dosage. The sow farrowing room should be thoroughly cleaned, washed, and disinfected. A disinfection pool and disinfection room should be set up at the entrance of the farrowing room, and vehicles and personnel entering and leaving must undergo strict disinfection. A regular disinfection system should be established during normal times. It is recommended to disinfect 1-2 times per week, prepare disinfectant fresh at the time of use, and carry out spray disinfection of pigs. This practice can inhibit and spread diseases and achieve the purpose of reducing the infection rate of diseases. Once an infectious disease is found on a pig farm, the pig house and equipment should be disinfected once a week, and in severe cases, once every other day. During disinfection, it is necessary to first clean the manure and dirt in the pen, then remove the surface soil, and finally use disinfectant solution for disinfection.
Isolation: It is strictly prohibited to introduce piglets andbreeding pigs，from affected pig farms.The best method that can be adopted by pig farms is self-breeding and self-raising. If it is determined that piglets need to be introduced from outside, they must be isolated and observed for 30 days. Once a problem occurs, it should be solved promptly to prevent the spread and transmission of disease. During normal times, feeders should do a good job in the prevention and inspection of pig diseases. Once an epidemic is found, it should be isolated promptly, and activelytreatedto prevent the spread of the epidemic.
In summary, pig digestive tract diseases have always been the main diseases troubling pig farms in autumn and winter, and the causes are very complex. For pig digestive tract diseases, pig farms must focus on prevention. While adopting immunization and drugtreatment, they should achieve scientific and standardized feeding management, do a good job in biosafety measures, and establish a series of comprehensiveprevention and controlmeasures to ensure the sustainable and stable development of pig production.