You find a lost dog. You’re a good person so you want to get the little fella back to its rightful owner. Do NOT post a picture of the dog when advertising that you have found a lost dog! Simply post (on Facebook, Craigslist, fliers, etc.) that you have found a lost dog and to call or email you with information. Then when someone calls you about the dog, have them describe the dog to you! Why? Because not everyone is as honest as you are and certain breeds like greyhounds, pitbulls, etc. are desirable for various reasons. There are some very bad people out there who are checking social media sites for lost dogs and pretending they are the owner based on the picture you’ve posted so they can be used as training partners in dog fighting circles. Besides, if someone is looking for their lost dog, they wouldn’t need a picture of their dog. They’ll be able to accurately describe the dog to you.
If it doesn’t have ID, call your nearest vet or shelter and ask them if they will scan it for a microchip. Most will do it for free although I know one vet in North Carolina who will charge you for the two seconds it takes her to scan a chip no matter the circumstance. I did this one time with a dog that showed up in my yard with no collar on. The dog had a microchip which came back with the owner’s number and she was home within the hour.
The reason it’s so important to contact the animal control agency is that most people that have a missing pet will call the local shelter but not everyone will find your post on Facebook or Craigslist. Flyers are great but animals can travel a far distance before being found. When taking these steps, you can list details that are unlikely to make the pet more or less desirable but could help identify it — general things like primary color or that it was found with a red collar or even approximate weight, location the dog was found, etc.
If it’s a dog that looks like it gets groomed, take it to nearby grooming shops. A friend of mine works in a grooming shop and she has identified two lost dogs and helped them find their way home.
Finally, if you have your own pets at home, LEAVE the dog at the nearest vet or shelter! You have no idea about the medical history of the dog or what diseases/parasites it could have encountered and could give to your pet. If you do not have your own pet and are interested in adopting the lost dog if it is not reclaimed, most shelters allow you to place a CIP (Call Interested Party) hold on the dog.