Wolf King still lacked the ability to express his thoughts as precisely as humans, but he possessed the intelligence of a child of several years old, was capable of simple reasoning, and had improved intellectually with the help of Suming and Friends of the Animals after some time of interaction.
During this time, he had been howling to Suming, conveying a simple message: freedom.
Freedom is something ingrained in the bones of all wild animals, who would rather endure hunger and cold, battle with nature and humans, and fight other ferocious beasts than to be kept in cages as pets for people's amusement.
The Wolf King and his mate were old and had lived in the zoo for many years. Even if they went to the wild, they most likely wouldn't adapt and wouldn't survive.
But it was different for the wolf cub; it was still young and fully capable of adapting to life in the wild, returning to the vast nature instead of spending its lifetime in this iron cage, being gawked at by people.