they recognize voice and smell of feet as they wake up smelling feet, walk in the park smelling feet, eat their meals smelling feet, lie down to rest smelling feet. if amdl were to remove her boots and socks her dog would have instantly recognized her. if i were gone for 6.9 months in sg, my dog could smell the dirty hawker and food court floors on my shoes and vomit. thus i change my socks and shoes whenever i get home after a long trip.