Sequin,
No, it's not the first time their dog has come over, it's just the first time in a while. It is the first time he's come over since we've been letting our girls free range (they're only 14 weeks).
I am very seriously considering putting up a strand of barbed wire along the top of our fence, as I believe that would fix our problem nicely. The problem with electric fencing there is that we have a lot of brush and trees, so I think we would have a difficult time keeping it hot.
I understand what you're saying about responsible dog owners, and irresponsible dog owners. As I mentioned, I have an exceptional red heeler. She's out with the chickens all day, along with my lab (both breeds known for attacking chickens). The neighbors have a boxer, who they have no control over at all. I would NEVER consider owning a boxer if that was the only one I knew.
SpottedCrow - I agree, I think that's the thing that bothered me most about the conversation with her... these birds are pets, not something to be exchanged at will.
Chicks4kids -
I'll have to try that! I'll bet a few rounds fired would scare this dog off for a while. If I see him over here... I like that idea more than killing somebody else's pet. I will if I have to, but I'd prefer not to.