Write letters to the editors of your local paper, and let the public know that pet theft happened in your area, and warn people to please watch their pets carefully and to report any suspicious vehicles or people to the local law enforcement agency. Send a flyer to them. If you can, find others on the web with your breed of dog, and ask a few to help spread the word. Whoever has your dog may try to breed it, and may contact someone with a bitch or stud of that breed. Watch for the puppy ads of your breed if your dog is not found and is not spayed or neutered.
Some breeds have a page for lost dogs of that particular breed.
You can also hand out flyers at any nearby dog shows, and get a catalog. You might send flyers to the handlers and owners listed there. Call radio stations and tv news stations. Give a good description of your dog, and be aware that not everyone will know what breed your dog is. You must be very clear in describing your dog.