It is not enough to have a cat, and it is not enough to have a dog.

The original sentence should be that chickens are not more than six years old and dogs are not more than eight years old, which means that the normal life span of chickens is six years and that of dogs is eight years.

The book Yi Yao tells some bizarre stories. The book is about the Jin Dynasty, but there are only six chickens and eight dogs, which comes from this ancient book.