Actually when I was younger my father wanted to get me a dog (I still have no idea why, because I am petrified of them!) but anyways, he asked a Rav if he is allowed to get one and the Rav said halachically there is no problem, however it is not something a yiddishe home should have, and on shabbos a dog is muktza so you would have to send it away ever shaboos.
Besides the point who over here really wants a dog??