The dog gave birth to four babies.

There is a folk saying that two cats and one dog have more sex, which means that people who encounter this situation will be developed. It's actually a homophonic terrier.

Dogs belong to Carnivora Canidae. Dogs are distributed all over the world. There is also a "hierarchy" when living in groups, which can maintain the stability of the whole group and reduce the struggles and wars caused by competition for food, living space and the opposite sex.