paul douglas of the bristol county sheriff’s office and huntah, his covid-detection dog, outside one of the sites they regularly screen: freetown elementary school in freetown, mass. jodi hilton for npr hide caption duke, one of the covid-detection dogs from the k-9 unit of the bristol county sheriff’s office, sweeps through a classroom at freetown elementary school. these differences give dogs a leg up — or perhaps four legs up — in the realm of smell. and even if dogs …