obviously the people do not care about the dog. perhaps if you approached them and suggested that you know someone who would like to have it and offer then something for it they would take your offer, cause evidently the dog means nothing to them.
On another note, I have a thing about dogs being left outside especially small dogs. Whay do you even have a dog if it is not inside where you can enjoy it and it can enjoy you.
Maybe you can help it dig under the fence and escape.
