I am so sorry, Dedalus.
The problem is that even if your neighbors acknowledge responsibility, even if they keep their dogs confined, that is no assurance that the same thing, or something similar, won't happen to your other cats. There are other dogs who may get into your yard, not to mention wild animals like foxes, coyotes, raccoons, etc. Just a few weeks ago, a friend who lives in town went out into her attached garage and came face to face with a coyote. Fortunately, she had brought her cats in for the night that particular day - often, they stay out all night.
Cats are at risk from so many animals. Here, I have outbuildings that cats can shelter in, not to mention that my own dogs act as a deterrent to larger predators. And still, those cats who I have not been able to bring into the house because I've simply run out of room last less than a year.
Can you bring your cats in at night? Or build them some predator proof shelter in which you can confine them at night?