Special topics on swine diseases: What is Porcine Infectious Gastroenteritis (PIG)?

Pathogen:

Porcine Infectious Gastroenteritis (PIG) is a highly contagious intestinal disease in pigs. It is characterized by vomiting, severe diarrhea, and dehydration. Pigs of all ages can be affected, with mortality rates in piglets under 10 days of age being very high, up to 100%. For pigs older than 5 weeks, mortality is very low, and adult pigs rarely die.

Epidemiology:

Infected pigs and carrier pigs are the primary sources of infection for this disease. Pigs of all ages can be infected and show mild symptoms, often recovering naturally. However, piglets under 10 days of age have the highest incidence and mortality rates, with mortality decreasing steadily as age increases. Other animals are not susceptible to this disease. The occurrence of the disease shows seasonality, with outbreaks more common in the cold winter and spring months (January to February being peak infection periods), and less frequent in summer. Outbreaks are also more common during the peak farrowing season. The virus is transmitted primarily through direct contact between pigs. Sow’s milk can also harbor the virus, transmitting it to suckling piglets, and the disease can also spread through the respiratory tract. Virus-contaminated feces can be orally or nasally transmitted. Pigs recovering from the disease can shed the virus for up to 8 weeks, making them a major source of infection in affected farms.

Symptoms:

The typical clinical signs in piglets include sudden vomiting, followed by severe watery diarrhea with yellowish or pale green feces. Infected pigs rapidly become dehydrated, lose weight, appear lethargic, and have rough, dull fur. Suckling piglets may reduce or stop nursing, show signs of tremors, thirst, and emaciation, and often die within 2-5 days. Mortality in suckling piglets under one week of age can range from 50% to 100%, with mortality decreasing as the piglets age.

In growing pigs, fattening pigs, and adult sows, symptoms primarily include loss of appetite or complete loss of appetite, watery diarrhea with yellow-green, egg-gray, or brown feces, often with bubbles. Lactating sows may have reduced or stopped milk production. In these animals, the disease usually improves after 3-7 days with recovery, and death is rare.

Lesions:

The body of infected pigs shows significant dehydration. The main lesions are found in the stomach and small intestine. The stomach is filled with curd-like masses, and the gastric mucosa is congested, sometimes with hemorrhagic spots. The small intestine shows thinning of the intestinal wall and is filled with yellow-green or white liquid containing bubbles and curd-like masses. The mesenteric lymphatic vessels are devoid of chyle, and the small intestine wall is thin and translucent, with dilated intestines filled with semi-liquid or liquid content. The villi of the small intestine mucosa are atrophied.

Prevention and Control:

1.To prevent the introduction of the disease, do not purchase pigs from infected areas, especially during the high-risk winter and spring seasons. Isolate and observe all newly purchased pigs. If an outbreak occurs, immediately disinfect with Roxycide disinfectant powder and isolate infected pigs. Sows about to give birth should be placed in disinfected farrowing pens.

2.Regularly disinfect pigsty environments and maintain good husbandry practices. Ensure cleanliness in the environment, provide proper warmth and protection from cold, but avoid excessive humidity and heat. Fresh air should be maintained in the pigsty to enhance the health and disease resistance of the herd.

3.Implement vaccination programs. For large-scale pig farms and areas with a history of the disease, use a weakened live vaccine for infectious gastroenteritis. Pregnant sows should be vaccinated 20-30 days before farrowing with 2 ml per sow. For newborn piglets, administer 0.5 ml per piglet, for pigs weighing 10-50 kg, administer 1 ml, and for pigs weighing over 50 kg, administer 2 ml. The immunity period lasts for 6 months.

4.During outbreaks, an emergency control measure is to use Newcastle Disease Virus (NDV) strain I vaccine for pigs, diluted 50-100 times.

5.During disease outbreaks, it is advisable to withhold food or reduce feed intake, and promptly administer fluids. Provide a large amount of isotonic glucose saline solution and clean drinking water to help larger pigs recover more quickly and reduce mortality in piglets. For piglets unable to drink, administer intravenous or intraperitoneal injections of a 5%-10% glucose solution combined with Gentamicin and 5% sodium bicarbonate or a glucose-glycine solution (glucose 43.2g, sodium chloride 9.2g, glycine 6.6g, citric acid 0.52g, potassium citrate 0.1g, anhydrous potassium phosphate 4.35g, dissolved in 2 liters of water). Oral electrolyte solutions can also be administered.

6.Use antibiotics to prevent secondary infections and alleviate symptoms. Although antibiotics do not directly treat this disease, they can effectively prevent or treat secondary bacterial infections that complicate the disease. Common secondary infections include Escherichia coli, Salmonella, pneumonia, and coccidiosis, which can exacerbate the disease and contribute to mortality.