My mind would never make the leap from yelling and closed blinds to child abuse and poisoned dogs.
I live in a subdivision and the blinds at the back are always closed!! I also think some families just yell. It doesn't equal abuse. You said yourself they don't degrade the kids. So, while it may not be how you do things it is really none of your business. You could nicely ask them to try to be quiet as you have children sleeping.
If you see/hear abusive things that is obviously is a different story but it doesn't sound like it in this situation.