This is a real problem, and lacks much of a good solution. One of the best things might be to pick up some of the commercial material sold at lawn and garden stores. It is meant more for flower beds, but a band around the edge of your property might help.
There was a long thread here recently on cats, but had some good ideas that might work on dogs too. Rather than try to summarize it, I will give you a link,
http://www.askmehelpdesk.com/cats/ideas-dealing-stray-neighborhood-cats-6270.html. Not everybody liked my ideas.