I'm trying to figure out what a computer would even want a pet for? If you think about it, computers only know what we teach them, their entire logic is made up of 1's and 0's, no emotion, no want, no care. While it is possible to simulate emotion in certain robots it is not possible to actually give them emotions.
We as human beings keep pets to entertain us, as friends and loyal creatures. But if the above is true then computers can not be entertained so they'd have no desire for pets, nor would they desire to take over the world unless we specifically told them to. (Which considering some humans in the world I guess that could be a possibility.)
Ahh oh well, if it happens I just hope I'm lucky enough to be one of the dogs they use to breed with.
See that? Optimism!