You should do one of the following:
1. Contact your local animal control to pick up the dog/puppy.
2. Follow the steps below to attempt to locate the owner (actively search for 7 days) while you care for the dog/puppy:
Report the stray dog/puppy to your local animal control. Check with your local shelter for specific requirements in your area.
Check with the local humane society, animal shelters, rescue groups and veterinarians to see if anyone has reported a lost dog/puppy. The shelters and vets usually keep a Lost/Found pet list to help owners reunite with their pets. It is best if you call as many as you can. Most people contact these places first to advise them of their missing dog.
It is very helpful if you can also take the dog/puppy to a veterinarian to have them check for a microchip to identify the owner.
Place a “found” ad in at least one local newspaper. When placing the ad, be general when you describe the pet, as you will want all callers to describe the dog/puppy’s unique characteristics in detail in order to confirm that this is the actual true owner. Some dishonest people may try to claim an animal which does not belong to them.
Post flyers around the area you found the pet. Include places that have bulletin boards, such as pet stores, shopping centers, gas stations, and farm supply stores.
If, after actively searching for one week (7 days) as described above, you are unable to locate the owner, the dog then belongs to you. You can keep the dog or try to find a new home for the dog.