Bless you for wanting to take in this angel!
I rescued my Sam from a supposedly loving home. He looked a lot like this baby, without the injuries. He even had hair loss that the vet thought was demodex. Three scrapings later we had ruled that out. His previous owner had starved him and he was starved for attention. He spent all day crated and then went back in for the night after a few minutes out (Usually being bathed and fussed at for messing his crate.) He was seven months when we got him and so emaciated his ribs, spine, hips, and shoulders stuck out. He weighed only 50 pounds when I took him to the vet after a week to have him checked for worms. He had none. I contacted the previous owner about his weight. He said that he was giving him the recommended amount of food and that his vet said the dog was just skinny. I got the vet records and he had been to the vet twice to be checked for worms. Some vets are as bad as the owners who neglect their dogs. After a change to a combination of Nutro puppy and Nutro High Performance, supplemented with pumpkin and yogurt (to help with the gas), he is healthy as a horse and at 1 year weighs in at 70+ pounds. He is still on the thin side, you can see the outline of his ribs. Lots of love, small meals and quality kibble and you will see miracles!
Best of luck to you both!
Karen, Sam and Heidi