I am sorry to hear that Chris. Hell is other people.
We have a similar situation on the ground floor where the tenant is borderline senile squalor syndrome, which is also called Diogenes syndrome I think. She used to have three boxer dogs too, and never ever cleaned up after them, though thankfully the dogs have now gone. But if you go into her home the rubbish is piled up to the roof. I worry that it might bring vermine into the building, but beyond that it does not bother us. No smells as we are two floors up on the other side of the building. But we have thought about talking to social services about her.