Lost male dog, Hattiesburg — 9-month-old puppy with white muzzle and chest

Lost off Highway 49, North Camp Shelby gate area I am frantic that he got loose and left our home area. He's an inside dog, not accustomed to being on his own and we are right off Highway 49. He's still just a puppy (9 months) and I am worried sick. He's microchipped. Weighs about 65lbs but is short and stocky. He has white around his muzzle and on his chest, and darker areas on either side of his neck, as shown (almost like he's wearing a pair of headphones around his neck).