Diagnostic Methods and Prevention and Control Measures for Swine Erysipelas

I. Epidemiological characteristics. This disease mostly occurs in feeder pigs aged 2-6 months. Diseased pigs and carrier pigs are the main sources of infection for this disease. The main route of infection is the digestive tract, but it can also be infected through skin wounds, or transmitted by blood-sucking insects such as mosquitoes and flies. This disease can occur in all four seasons.

II. Symptoms and lesions. Clinically, this disease can be divided into acute, subacute and chronic types.

Acute type: namely the septicemic type, the body temperature of diseased pigs suddenly rises above 42°C, they refuse to eat, have an unsteady gait and may even lie down and be unable to stand. Conjunctival congestion, eyes bright and spirited. Red patches appear on the skin of the chest, abdomen and inner thighs, which fade easily under finger pressure and then immediately return to red. The course of disease is short, with sudden death, and the mortality rate reaches 80-90%, or it turns into the urticarial type or chronic type. When suckling piglets and just-weaned pigs develop swine erysipelas, they generally become ill suddenly, with neurological symptoms, convulsions and falling to the ground to death, and the course of disease generally does not exceed 1 day.

Subacute type: At the beginning of the disease, body temperature rises to around 41°C, with poor spirit and appetite, and constipation. After 2-3 days, clearly demarcated urticarial patches appear on the chest, abdomen, shoulders, back and limbs, in square, diamond or roughly circular shapes, slightly raised above the skin surface, with a diameter of about several cm. They feel hard to the touch. Mild cases subside after several days and recover on their own, while severe cases form brownish-red scabs that remain unchanged for a long time. Some turn into septicemia or the chronic type. The course of disease is 1-2 weeks, and the mortality rate is relatively low.

Chronic type: The joints of the limbs of diseased pigs become inflamed and swollen, with lameness; pigs with endocarditis have difficulty breathing, cyanosis of visible mucous membranes, weak constitution, slow growth, a long course of disease, and relatively few deaths. Necropsy shows fibrinous exudate in the joint cavity; cauliflower-like vegetations can be seen on the surface of the heart valves.

III. Diagnosis. A preliminary diagnosis can be made based on epidemiological characteristics, clinical symptoms and necropsy changes. Atypical cases require laboratory testing.

IV. Prevention and control measures

1. Vaccination: (1) Inactivated swine erysipelas vaccine: inject aluminum hydroxide inactivated vaccine subcutaneously or intramuscularly, with 5 ml for 1 immunization, and the immunization period can reach 6-8 months. (2) Attenuated live swine erysipelas vaccine: when using the GC42 attenuated vaccine, dissolve it according to the number of doses specified on the bottle label by adding 1 ml of 20% aluminum gel physiological saline, and always inject 1 ml subcutaneously; for oral administration, use 2 ml per pig, and the immunization period is 6 months. (3) Inject the triple live vaccine against swine fever, swine erysipelas and swine pasteurellosis, or the aluminum hydroxide bivalent inactivated vaccine against swine erysipelas and swine pasteurellosis; the immunization effect is the same as that of the single vaccine.

2. Drug treatment: (1) Amoxicillin powder for injection, intramuscular injection at 15 mg per kg body weight, 1-2 times daily, for 2-3 consecutive days. (2) Penicillin, intramuscular injection at 20,000 units per kg body weight, twice a day, for 2-3 consecutive days. (3) Ceftiofur powder for injection, intramuscular injection at 20,000 units per kg body weight; 1 injection can maintain drug efficacy for 9 days. (4) 10% sulfadiazine sodium injection, 20-40 ml per pig per day by intramuscular injection, 1-2 times daily. (5) Anti-swine erysipelas serum also has a relatively good therapeutic effect.

3. Strengthen feeding and management: (1) Do a good job in pig pen and environmental hygiene, and disinfect regularly. (2) Do not introduce pigs from epidemic areas. Newly purchased pigs must first be isolated and observed for 2-4 weeks, and only healthy ones may enter the pig herd. (3) Strict quarantine system to prevent all virus-carrying animals and contaminated materials from entering the pig herd.