It has struck me that the majority of pets owned today are actually in solitary confinement. Most of them come from social structures that are usually composed of many individuals in nature: packs of dogs, clowders(?) of cats.
We disappoint our pets every day, closing the door on their questioning faces, and condemning them to an unknown and unknowable period of solitary confinement.
Unless of course, you have multiple pets. This was the major driver for me to have two dogs, and to now have three cats (not simultaneously). At least they have each other while the humans are away, doing whatever it is that humans do.