It seems I must remove their dog from their home. Now what?

My biological father states that he loves his 6 y/o German Shepherd more than me or my stepmom. That's fine with us. I'm not an animal person since my kid went to college, and my stepmother is quite practical, so I doubt she cares too much what we do with this poor beast.

My father and his wife have ***NO MONEY***. The dog walker will be $17/visit x 7 days a week. The problem is, the animal is reacting badly to their stress. I found out that my stepmother was under-feeding it for years so that it didn't "get fat". It's 40 lbs underweight! I finally got it to a vet 3 days ago, who told her to double the food she gives it. The vet also found a LOT of health issues we're trying to resolve. ($1K so far!) The dog has lost much of its hair, bites itself and is bleeding from every joint because of a weird skin condition.

8 days ago, I moved them and the dog to my state and into a clean, well-appointed condo. They were in a filthy, dilapidated hovel in rural Missouri. They were letting the dog out X times per day into a poop-filled, disgusting little 12x12 yard they had built literally attached to their front door (You had to walk through poop to get to the cars!). No one told me that my father didn't have the strength to walk the dog, and my stepmother is so handicapped now that she can't either.

The dog has peed, pooped and vomited on the carpet numerous times every day since they got here. My father, who is more physically capable, sits and watches as his crippled wife gets down on her hands and knees to mop up urine with paper towels, then struggles painfully to use her walker to get back up. The carpets had been professionally cleaned 10 days ago. There was an oatmeal container in the middle of the floor when I arrived today. It was very heavy when I picked it up. It was...full of dog poop! That's where they're keeping the poop. It must have weight 6 lbs! Neither of them has the physical strength to carry a 6 lb canister of dog poop to the trash can 6' away. Really!

Since neither of them can manage the animal's needs, and since they cannot afford the vet bills, and since I cannot/will not manage the animal for them, and since they cannot afford the dog walker even once a day...I am not sure what to do. A friend suggested I take it for a walk and let it "run away", while secretly giving it to a German Shepherd rescue. I'm afraid that will kill my father! Another recommended I get it euthanized, which is equally traumatic for them and for me.

Here's the problem: My illogical father has told his wife and me that if the dog doesn't like the new home (it doesn't so far) then he's going to get a travel trailer and drive to a wooded lot that he will buy somewhere (where?) that is fenced (!?!?!) and live out his days in the woods, without power, water or plumbing. OR he's going to fly to Argentina (?!?!?) with the dog and live there. No one is sure how he plans to do these things, but this is what he tells us daily.

The dog needs to go. That's obvious. It's the biggest problem in their lives right now. They cannot afford this animal, they cannot care for it, and it is suffering in many ways. However, my father's suffering will be enormous if I take it away, especially if it is intentional. My father was crying on my shoulder (literally) tonight because he doesn't know where he will find a fenced wooden lot. He's happy enough to leave his wife in my care forever, but he doesn't want to leave the dog. What do I do? I've been their caregiver for 8 days. Help!

Help?