1, Streptococcus pyogenes: Streptococcus pyogenes often infects suckling piglets, showing acute death and died when found. The anatomy of farmers showed that inguinal lymph nodes were congested, a small amount of cellulose oozed from abdominal cavity, and the spleen was swollen and congested. However, organs such as lungs and kidneys often have no typical clinical symptoms.

2. Porcine pneumonia: Porcine pneumonia mainly infects large and medium-sized pigs, which is also called throat lock madness clinically. After the onset, sometimes farmers can see the neck swelling of sick pigs. Acute porcine pneumonia has obvious dyspnea, abdominal respiratory symptoms and subacute symptoms similar to infectious pleuropneumonia, and will not lead to the death of pigs. Anatomy shows that the boundary between infected lung and normal lung is obvious, and there are a lot of white foam in trachea.

3. Infectious pleuropneumonia: Infectious pleuropneumonia mainly harms large and medium-sized pigs. Before the death of sick pigs, there will be symptoms of dyspnea such as dog sitting breathing and abdominal breathing, and red or white foam will flow out of the nose after death. Streptococcus pyogenes mainly causes the acute death of suckling piglets, while contagious pleuropneumonia mainly causes the acute death of Zhongda pigs.