Because this symbol means "snake winding rod", because this kind of rod was used by ancient wizards. Wizards were doctors or veterinarians at that time. So this symbol was adopted, and the logo of the animal inspection suit was a snake.

Animal quarantine conducts epidemic disease inspection on various animals and their products according to national laws and regulations. Through animal quarantine, the suspected or confirmed epidemic objects are forcibly isolated or properly treated, with the aim of preventing the spread of animal infectious diseases and ensuring animal husbandry production and people's health.