I've got two Borders myself and I've never known such a nosey breed of dog.They want to know everything you've got in your hands or shopping bag, sniff every tree, get in every bush thus I would call him nosey or Inky ( short for inquisitive).
Or on a motoring theme Satnav cos they always know where they are going!
Or on a motoring theme Satnav cos they always know where they are going!