Dogs are carnivorous mammals in the family Canidae, also known as dogs, and are referred to as the "six livestock" along with horses, cows, sheep, pigs, and chickens. The size and fur color of dogs vary depending on their breed, and their physique is well proportioned; The nose and snout are relatively long; The eyes are oval in shape; Two ears, either vertical or vertical; Limbs agile, with 5 toes in the forelimbs and 4 toes in the hindlimbs, with claws that cannot stretch or retract; The tail is circular or sickle shaped. According to Li Shizhen's "Compendium of Materia Medica", "Dog" means to knock. Dogs bark rhythmically, like knocking on objects, and some people say it is called a dog because of its roughness.