Brown and white terrier mix, lost near Texas State campus

I lost my brown-and-white terrier mix yesterday around 3pm near the Texas State University campus in San Marcos on Aquarena Springs Drive, by the LBJ Student Center. He's a medium-sized guy, about 20 pounds, with a bright red collar and a small silver tag that has my number. There’s a heart-shaped white patch on his chest and a tiny scar on his left hind leg that you can spot when he lies down. He’s a bit shy with strangers but warms up quickly, and he’s been my hiking buddy since I adopted him last year; this dog means the world to me. If anyone spots him, please text me—I’m really worried and would be so grateful to bring him home.