I think the first thing you should do it set up an appointment to talk to your parents family doctor, raise your concerns about the health issues the filthy condition of the house may be causing.
From there the doctor should have resources for you to speak to a mental health professional about an assessment regarding the hoarding as this can be a mental health condition.
After assessment the steps will be in place to start to have the house cleaned & some if not all the dogs removed & rehabilitated.
Avoid biting when a simple growl will do
The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying
Vindication ~ For all those pets who became sick or lost their lives from tainted pet food