I actually just talked to DH about this a little while ago.
I can't seem to get any info from the neighbors, and unfortunately there's no good way of seeing back there without actually walking into their yard, so I can't really tell what's going on.
The good news is that it's happened a lot less this week, but still sounds like s/he's outside and occasionally (i.e. maybe 20 minutes at a time 3-4 times a day now) just screaming bloody murder. I've tried calling animal control, but they never pick up. There's a JSO officer who DH is friendly with, and he's offered to stop by in the next few days to check the situation out.
Re: Neighbor's dog update