Poor Starved Pregnant Little Gal

This little ( weighted all of 22 lbs) girl is approx 1 yr to 16 months old. She has had litters before.
I picked her up at the shelter today to go to the vet. He only needed one look to see that she was in bad shape. Really bad.
She has been starved. She looks fat when you first see her but when you look closely you realize she is bloated. Her back bones, ribs, neck bones are all protruding. She is breathing very shallow. She is a "hot" heart worm positive. She has guardia, hook, whip and round worms and she is PREGNANT..
So sad. Dr Williams at The Animal Health Center in Sikeston MO isn't sure she can take a heartworm treatment and of course that would only happen after the puppies are weaned. I am concerned she won't survive that long. Her shallow breathing is not a good sign. Do we abort, do we try to save her or the pups? So many questions. I say we save her. Dr Williams thinks she is only half way through the pregnancy. I am betting two weeks away..no more then 3 for sure.
Why do people let this happen to their dogs? Why don't they know that heart worm preventative is very reasonably priced. One lunch out a month will pay for  preventative and save the dog's life. It is so easy and yet so many people in this area choose  not to use preventative on their dogs.

Owning a dog should require a written test . IF you fail , well better for the animal they not be placed in that home. I am all for it.......same with kids.. would cut down on the over population there too.