Your neighbor has no right to allow their dog to roam the streets, and especially your yard. Keep in mind that you don't pay good money for a place to live so that others can impose unnecessary inconveniences on you. I would make it well known that the second you see the dog wandering into your yard or out onto the street (without a leash), you will call animal control, and then follow through on the threat. People need to learn to be responsible for their pets, and often they are coddled into thinking that it is alright to allow their dog to do what it wants.
I have a 5' chainlink fence around my yard (actually wish it was 6'), with locked gates, and a locked enclosure for my russians (my redfoot gets free roam of the yard when we are able to give him direct supervision). I still do not feel comfortable leaving them in their enclosure when I am not outside to watch them, because we have a problem with the worst of feral animals... pre-teen and teenage kids. Over the summer they have followed the creek into our backyard (the creek lies outside of the fence), and proceeded to take snapping turtles, snakes, and frogs, as well as kill several of the largest water snakes that lived back there, and wounded a duck. I would hate to know what they would do if they knew their were tortoises in that enclosure. We have called the police on them several times, as well as chasing them off of the property, and following them home in a vehicle (they are a lot less cocky when their parents find out what they have been up to).
You just have to exercise your rights as a property owner, even though it will make you feel like a jerk. You have the right to do so. I know of a woman that was having trouble with her neighbors dogs who would come in and raid her chicken coup. She called animal control who came out to talk with the dog owner, and told the woman that she has every right to shoot the dogs if they are on her property and damaging her property (namely, the chickens). The neighbors learned the lesson quickly. That's a bit extreme though
