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How are affected pigs identified? The Ministry of Agriculture publishes the criteria

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Recently, the Veterinary Bureau of the Ministry of Agriculture and the China Institute of Veterinary Drug Control jointly compiled and issued the "Safe Use Manual for Inactivated Vaccine against Highly Pathogenic Porcine Reproductive and Respiratory Syndrome," publishing the quality standards for the inactivated vaccine against porcine reproductive and respiratory syndrome, and also publishing the criteria for identifying affected pigs. The manual stipulates that the criteria for identifying affected pigs are: a body temperature above 41°C for at least 3 days; decreased spirit and appetite, conjunctivitis, and respiratory symptoms such as coughing and wheezing; and on gross necropsy, patchy consolidation appearing in the apical or cardiac lobe of the lungs. Meeting the above three criteria means

Recently, the Veterinary Bureau of the Ministry of Agriculture and the China Institute of Veterinary Drug Control jointly compiled and issued the "Safe Use Manual for Inactivated Vaccine against Highly Pathogenic Porcine Reproductive and Respiratory Syndrome," publishing the quality standards for the inactivated vaccine against porcine reproductive and respiratory syndrome, and also publishing the criteria for identifying affected pigs.

The manual stipulates that the criteria for identifying affected pigs are: a body temperature above 41°C for at least 3 days; decreased spirit and appetite, conjunctivitis, and respiratory symptoms such as coughing and wheezing; and on gross necropsy, patchy consolidation appearing in the apical or cardiac lobe of the lungs. Meeting the above three criteria means the pig can be judged as affected.

The inactivated vaccine appears as a milky white emulsion of the water-in-oil type. Take a clean pipette, draw a small amount of vaccine and drip it into cold water; except for the first drop, none should spread. Its quality can be tested by the following methods:

1. Use a 1-milliliter pipette (lower opening inner diameter 1.2 mm, upper opening inner diameter 2.7 mm) to draw 1 milliliter of vaccine at about 25°C, let it flow out vertically and naturally, and record the time required for 0.4 milliliters to flow out, which should be within 8 seconds.

2. Use 5 pigs aged 3-4 weeks that are negative for PRRSV antigen and antibodies, inject 4 milliliters of vaccine into the muscle behind the ear of each pig, and observe for 21 days; no local or systemic adverse reactions caused by the vaccine should appear.

3. Use 10 pigs aged 3-6 weeks that are negative for PRRSV antigen and antibodies, of which 5 are injected with 2 milliliters of vaccine into the muscle behind the ear, and the other 5 serve as controls, raised under the same conditions. After 28 days, all pigs are injected with 3 milliliters of virulent PRRSV NVDC-JXA1 strain (containing 105 TCID50) into the muscle behind the ear on the opposite side, and their temperature is measured daily and they are observed for 21 days. All 5 control pigs should become affected, and at least 2 should die; at least 4 of the immunized pigs should remain healthy and alive.

The manual states that single-dose, repeated single-dose, and overdose inoculation of piglets is safe, and it should be used only under veterinary guidance. After vaccination, piglets have good spirit and appetite, and there are generally no visible adverse reactions at the injection site or throughout the body; inoculating sows will not cause miscarriage, and a small number of sows may experience a transient decrease in appetite, which can recover within 1-2 days.

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