.017 - the one untapped game demographic

My roommate just showed me this hilarious video of a dog howling along with the wolf in Zelda: Twilight Princess. And it made me wonder...why isn't entertainment made for pets too?
It know it sounds funny(and it might be because its 3am), but there's a bit of revelation under this idea of non-human game design. Sure dogs can't really understand movies(or at least I don't think they can), but they can move and bark. And given the recent rise and success of movement-based games(including the motion sensing Wii and games like DDR and Guitar hero), doing something as crazy as that can't be that unreasonable.

What if one day instead of walking your you could put him in front of video game where he walks his self? What if he could also learn to sit through the same experience? Better yet, what if Lassie could undergo his/her own adventure without tearing up your house?

The benefits of making games for pets are endless, but yet why do we continue making games just for our entertainment?