I would not in my wildest dreams leave my home with my dogs left outside, even with a very well fenced and well planned yard. Why? I agree with all the reasons that have already been covered. However, my worst nightmare would be to come home and find that anyone, adult or child, had entered the yard and left the gate open or even more horrible that someone had plain and simple taken my dogs to be used for whatever reason they might have. I wouldn't leave my home and leave my children outdoors in the most securely fenced area. Why on earth would I do the same to my dog? Never, is the appropriate word, never is it OK.