eek!
This is deja vue, and not in a good way.
I lived in the same situation, except it was German Shepherd and not a Pit. The dog eventually did get into our yard on a winter's day when the snow was high and the neighbour was walking him in the back alley off leash. He easily got over the fence, jumped on my poor border collie from behind while he was having a poo, and chewed him up badly. He required surgery, a pin in his leg, thousands of dollars in vet bills, and I had to retire him from flyball which was an activity we both loved. The owner refused to pay for anything, because his insurance didn't cover it and it was just "dogs being dogs". I reported it to Animal Control, and they promptly came over and slapped a muzzle order on both our dogs. That in spite of the fact mine was not able to walk, in bandages, had a CGC certificate and FDX, and was clearly gentle. The GS went after the officer when she went into the neighbour's house to question the owner. The officer said she wasn't allowed to exercise any discretion in the matter, and apologized to me. The neighbour ignored the order, of course. It eventually went to a hearing and the muzzle order was lifted off my dog and the German Shepherd went into their records with a permanent muzzle order, which again, the owners ignored. Animal Control took no other action because it was a "dog on dog" attack.
I took the guy to small claims court, sued him and won. He moved away to avoid paying me (yay). I found him and served him papers. I took out a private warrant for his arrest when he still didn't pay. The police caught up with him on a traffic violation, and THEN he paid. It took two years. I don't know if I'd do it again knowing what a long, emotional, expensive process it would be, but justice was served. It wasn't about the money.
The summer after my dog was attacked, a woman was attacked and injured by this dog when she went on to their property by mistake. It could have been a child. It would eventually have been a child, except they finally got rid of the dog. I don't know what happened to it. I'm sorry the dog landed had such horrible owners. But I was very relieved - he was dangerous.
So my advice is this: Take whatever steps you can now to protect yourself and your pets. Put up the fence. Report the dog. If there's dangerous breed legislation in your town, take advantage of it. I'm not saying I agree with it, I don't. But this dog WILL attack, it's a matter of "when", not "if". Use whatever resources you have to prevent it from happening.
Sorry if I'm alarming you - I lived it. It's no fun.
