Porcine "chorophysis" is an acute infectious disease of pigs caused by Pasteurella multocida. It is also called porcine epidemic. The main characteristics of this disease are sepsis, throat and surrounding tissues. Acute inflammatory swelling, or fibrinous exudative inflammation of the lung pleura. The causative agent of this disease is Pasteurella multocida, a small coccobacterium that is Gram-negative and has the characteristics of dense staining at both ends. This bacterium has weak resistance and will die within 2 to 3 days after drying. It can survive in blood and feces for 10 days and in decaying corpses for 1 to 3 months. It will die immediately in sunlight and high temperature. It can survive in 1 caustic soda and 2 Lysol can kill it quickly.

This disease is susceptible to both large and small pigs, with a higher incidence rate in small and medium-sized pigs. Sick pigs and infected pigs are sources of infection. The pathogen mainly exists in the lung lesions and various organs of sick pigs, and in the respiratory tract and intestines of healthy pigs. It is excreted through secretions and excreta, and is transmitted through the respiratory tract, digestive tract and damaged skin. Swine pneumonia is often sporadic and can occur throughout the year, and sometimes it can become endemic.