(Photo Credit: Instagram / @carsonshelterpups) In a busy shelter, even the sweetest dogs can disappear into the background, especially when they’re scared. That’s exactly what happens to Hunter, an 81-pound shelter dog featured in a recent Instagram video shared by @carsonshelterpups. The four-year-old spends most of his time tucked into the back of his kennel, where he seems to feel a little safer. Volunteers explain that the shelter is so full…