Yep Make flyers post every where in stores near where there are public phones, Go to some houses handing out a flyer with picture
Call all the rescues in your area including the animal controls every morning and evening.. as for any dogs that are close to coloring of your dog not just the breed also Vets..again the color description ...I had someone call me on a lost dog that had a microchip I had implanted Owner did not register the chip in their name anyway The lady who worked at a vets office said she had a cattle dog in their possession which they traced the chip back to me

That red and white cattle dog she was describing was a purebred Brittany..I have seen GSP's described as Pit bull crosses,,why I say describe the coloring of the dog along with the breed
Good Luck..we also have had dogs return months later because of signs finally found to microchips being scanned and traced