Put your clothing or his bedding out and maybe he’ll get the scent. Post colored fliers on your car window, all around the area he’s missing from and at businesses and vets offices if allowed. (Put them in zip lock bags if rain is predicted.) Give some to the mail carriers and utility workers in the area. Notify animal control and check with them daily. I recently saw where someone was looking for their dog and offering a reward and gave fliers to high school students who helped them find their dog. Just a thought.