Please post his photo on every sign imaginable.
Visit local shelters every 2-3 days. Call an report his missing to every vet in the area. Even better, post a sign at every vet.

Make campaign-sized signs with his picture and post them along roads.
Go door to door with your sign.
Put your signs on mailboxes/door steps.


My dog Kiara was missing for 5 days, we were able to track her down because a guy saw our signs and spotted her. Never give up.

A few tips for the signs -

LOST DOG
<Photo>
NEEDS MEDICATION
$$$REWARD$$$
<phone number>


Even if he does not need medication, put that on there because it may keep someone from keeping him if he is sick, and they'd want to return him to you.

I wish you a lot of luck. I am so sorry. We went thru the same pain and it is horrible.