Go knock on their door and talk to them.I know they shouldn't let it on our property. I feel like next time I have to say something since they obviously aren't noticing how irritated I've been. I just hate being "that person" to teach people common sense. Ugh.
Everyone is so quick to call someone else into the situation (animal control)...they may not even know their dog is in your yard.
Talking to someone goes a long way.