http://www.yorkietalk.com/forums/mis...ml#post3536764
Here is an article about how and what you can do to maximize the chance of re-uniting a lost dog to their owner.
On the subject of the found dog; one day running scared and through bushes, and mud and fallen leaves, will leave a Yorkie looking pretty rough. One day without food, on a very small body, will be visually and palpatory perceptible on this Yorkie.
What is concerning is that a lump or bump on his body, may indicate a hematoma, a cracked rib, an unresolved allergic reaction to ticks/mosquitoes/snake bites. This dog should really be seen by a vet today or tomorrow.
When you do take this dog to the vet, any reputable vet will scan for a microchip, and then the process will be put in place to find the owner. Some breeders even tatoo their dogs, this is another way of finding out about the dog.
I hope everything is well with this dog. Good luck at the vets.