Special topics on swine diseases：Red Dysentery

Special topics on swine diseases：Red Dysentery

Pathogen
The causative agent is Clostridium perfringens type C, also known as Clostridium welchii type C. This is a Gram-positive, encapsulated, non-motile anaerobic bacillus with oval spores located centrally in the bacterial body. This bacterium can produce lethal toxins, mainly α and β toxins, which can cause enterotoxemia and necrotizing enteritis in piglets. After spore formation, the bacteria are highly resistant to external conditions.

Epidemiology
This disease primarily affects piglets aged 1 to 3 days, with very few cases in piglets older than one week. The mortality rate generally ranges from 20% to 70%, and it can sometimes reach 100%. The bacteria are commonly present in the intestines of sows and are excreted through feces, contaminating the sow's teats and bedding. When newborn piglets suckle the sow's milk or ingest contaminated material shortly after birth, the bacteria enter the jejunum and proliferate, causing infection. This disease affects pigs and sheep, and can also infect cattle, horses, chickens, and rabbits.

Symptoms
The disease can be classified according to the course of illness into the following types: most acute, acute, subacute, and chronic.

• Most Acute Type: Piglets may show symptoms within 1 day after birth. Symptoms are often not obvious, and affected piglets are weak, quickly becoming critically ill, and eventually die.
• Acute Type: This is more common. Sick piglets continuously pass reddish-brown, liquid feces containing grayish tissue fragments, and become increasingly emaciated and weak. The disease typically lasts for 2 days, with death usually occurring on the third day.
• Subacute Type: Piglets show persistent diarrhea. Initially, they pass yellow soft feces, which later become liquid, containing necrotic tissue fragments. Affected piglets become severely emaciated and dehydrated, typically dying within 5 to 7 days.
• Chronic Type: Affected piglets may have intermittent or persistent diarrhea for over a week, with feces being yellowish-gray and pasty. The jejunum appears dark red, filled with bloody fluid, and the villi are necrotic. The mesenteric lymph nodes are bright red. In prolonged cases, necrotizing inflammation predominates, with yellow or gray necrotic pseudomembranes on the mucosa, which can be easily peeled off. Necrotic tissue fragments are present in the intestinal lumen. The kidneys appear grayish, and ascites may increase with blood-stained fluid, and in some cases, pleural effusion may occur.

Prevention and Treatment
Good sanitation and disinfection of the pigsty and surrounding environment are crucial, especially in the farrowing house. The sow's teats should be cleaned and disinfected before delivery. Using Roxycide disinfectant can help reduce the incidence and spread of the disease. Currently, it is common to vaccinate pregnant sows with Clostridium welchii type C aluminum hydroxide vaccine and piglet red dysentery dry powder vaccine. The sow should be injected intramuscularly with 5 ml of the vaccine one month before farrowing, and a second dose of 10 ml should be administered 2 weeks later to immunize the sow. Newborn piglets can obtain passive immunity by suckling the sow's colostrum, which is the most effective method for preventing the disease.

Piglets should receive an injection of anti-porcine red dysentery serum, with 3 ml administered intramuscularly per kilogram of body weight. This provides adequate protection, but early injection is crucial for better efficacy. Once the disease is detected, treatment should include administering Cefotaxime, Florfenicol, Fluoroquinolones, Ligosan, Berberine, Sulphadimethoxine SMM + Trimethoprim TMP, or other medications by stomach tube, along with oral administration of Montmorillonite and Tannic Acid Proteins. Supplementing with water and electrolytes (water, glucose, NaCl, KCl, NaHCO3) is essential. In severe cases, Loperamide or Atropine may be used if necessary.