I had this exact problem last year, but with a cat. I knew for a fact that it lived with some local pieces of shit, it was starving, it had had at least one litter of kittens, and everyone considered it a pest except for me. They just left it out at all hours, in all weather. I was terrified that one day I'd see it starved to death, frozen to death, hit in the road or that some day someone would just get pissed off and call animal control. I was really, really attached to this cat, too.
A friend had a small insulated cat-house from when she had an outdoor cat who liked to sleep on her porch, and she loaned it to me. I put it out in the front yard and the cat slept in it just about every night. I gave her food and warm milk every morning.
Then one day, just around this time of year, I opened the door to take her warmed milk out to her and she was curled up in the dirt and mulch by my front door. She was alive...sleeping, waiting for me...but she had a crust of snow on her from where she'd been curled up waiting for me all night. And that was just about e-fucking-nough.
I called our local animal shelter and asked to speak to someone in charge. When the woman called me back, I gave her a rundown of the situation and e-mailed her pictures of the obviously starving cat. I'd also taken pictures of her asleep by my door with snow on her. I told her about the pieces of shit, how she was out at all hours in all weather, and how she'd already had a litter that summer. I told her about how the neighbor kids had a game of swinging her by her tail and letting go to see how far she'd fly. I told the animal shelter woman that I wanted to take this cat in, that I loved this cat, but I already had other cats and couldn't afford the veterinary care.
She made a deal with me. She said that if I made the cat "disappear", the animal shelter would cover the cost of her initial vet bills, including spay and FELV/AIDS check, etc. I would have to take the cat in and not let her out in the neighborhood again, but she would be mine and they would be okay with that. The pieces of shit could be prosecuted for animal abuse if they felt like protesting.
So one day she disappeared, one night in my garage and the next morning to the vet to get actual care. Got her spayed that day, got her checked out, got all her shots and started getting actual food into her. The other cats didn't like her at first, since they were used to regarding her as the enemy on the other side of the window screen. But I just kept her separated for a while and now she and my other female are the best of buddies. They wrestle and cuddle.
She's kind of poorly socialized, but what the hell else could one expect after the way she lived 3/4 of her life?
Anyway, now she's as fat and happy as the other cats and I don't regret what I did one bit.
If you're of a similar mindset, I would definitely go for the insulated house. Can you build an enclosure in the garage, maybe, for now? Just something to get the dog in out of the cold before the weather gets really bad. And maybe your local animal shelter could work out a similar arrangement, covering her spay if you take her in.
I don't know about you, but I couldn't have handled turning my cat over to a shelter. I was just too attached, and it sounds the same way with your pit.
Anyway, that's my two cents.
