Can't imagine why someone would dump Mulroney in a stranger's backyard, him being such a sweet dog. He might already be more than two years old but he's still got the personality of a pup. Oh look, a stick. Must make friends with it now. Oh look, a person. Must be best pal immediately. Only thing he didn't like, in fact veered away from and eyed suspiciously, was some Toronto Maple Leafs trailer parked by the shelter. Read into that what you want.
The best way to check on the adoption status of this dog (and other dogs and cats and other small domestic animals) is to visit Toronto Animal Services adoption website or call 416 338 6668 for the Toronto Animal Services South shelter. If the dog is no longer on the TAS adoption website, it's probably because it's been adopted already.