Have hope that he will turn up, especially if he is microchipped. A cat recently came into my clinic and we scanned her for a chip. Luckily she had one and we reunited her with her owner. She had been missing for 6 months and the owners thought she was dead. They were so happy to have her back. Most vets will let you post lost flyers too and we've gotten a few dogs reunited with their families that way as well.