Help for vet care for neglected puppy

We just had a 6 to 8 week old puppy chained in our yard when we were not home. We filed a police report and talked with neighbors, vets, etc. And no one knows whose it is. You can see all ribs and spine. He is covered in fleas and has worms. He doesn't eat dry food just yet so we are mixing dry and wet with some formula replacement. He is not chipped. We are needing help funding his first few vet appointments and needs for him.