Hi,
So sorry to hear about his story, but glad that you got him back, there are some strange people in the world.
When Halli had her first litter of pups about 2 years ago she lost quite a bit of weight, she wasn't wanting to eat the kibble for first few weeks and was refusing each time we tried to give it to her, so we started making her food and put her on a raw/natural diet, from what i can remember, it was a combination of beef mince, turkey mince, kangaroo mince, vegetables finely chopped (not a large amount), chicken carcass chopped up and also chicken wings chopped up into chunks, we also used pearl barley and lentils that had been soaked till they were almost in a mushy state, eggs, a very small amount of garlic(helps with keeping fleas away), liquid fish oil (three omegas), you can also use organs and muscle meats such as liver, heart, kidney, etc.
We used to make it in big batches on the weekend and then put the rest in zip lock bags or containers and freeze it and then defrost it the day before to feed it to her. She put all her weight back on in a very reasonable amount of time and helped with her coat and all round look as well. We have put all our dogs back on a similar model now (for a few months now), and they love it, there is never anything left in their bowls, and we can control exactly what they are eating and make sure they are meeting all their nutritional requirements as well.
We have revised the recipe quite a bit since we first started because our 3's needs change and variety makes sure they don't get bored with it, as well doing extensive amounts of research. But if you decide to do a raw/natural kind of diet and need a hand with anything let me know, my partner and i have done a fair bit of research on it and have quite a few recipes that we are more than happy to share, i am glad to help where/if i can.
P.s sorry this is a bit long and all over the place.