Sorry you lost your roo!!! Can you call animal control for assistance with the dogs that are running loose? Are the chickens in a fenced in are or free roaming? You may want to consider fencing them for a while until the dogs are deal with....Also, a lot of folks swear by electric wire to keep predators (other than owls, hawks etc.) out
We all have a significant investment of time and $$$$ in our birds. Since I have no patience with people who won't control their animals, I have a three step process for this type of issue. No exceptions. 1. Tell the owner with a warning if another incident occurs. 2. Call Animal Control or Sheriff. 3. If it happens again, BANG!!!.
It's my responsibility to keep them safe. Knowing that there are animals out there that will kill them, our chickens are well protected by a fenced run and coop that is locked up every night.
We are building apen right now even though a chain link dog lot wasn't enough. Also that's exactly what it was, somebody in the apartments near where we live didn't keep their dogs on a leash and let them pack up!