In clinical practice, if the samples of diseased pigs need to be sent for examination, the one with a relatively typical clinical disease should be picked out, preferably representing the characteristics of the disease in the whole animal group. The typical tissues of the disease were collected from one or two dissected pigs, mainly lymph nodes, spleen, lungs, kidneys, serum, and tonsils. For the detection of antibodies or pathogens in sows, it is easier to carry out by collecting umbilical cord blood than collecting blood through the ear vein or anterior vena cava in clinical practice.