A good dog will smell and hear invaders (like sneaky night-time garden raidin' deer... oh, and skunks, so sniff out the door first before engaging dog) from inside the house, and will tell you about it, at which point you can let loose the dog of war or hie out there yerself, popgun in hand.

Purebred Labs confuse me. When I was a kid long ago, Labs were tall huge black dogs with long legs. All the Labs I see now seem to be short-leggedy critters with barrels for bodies.

If you were in Nova Scotia, I'd recommend a Nova Scotia Duck Toller, lovely medium size quiet dogs. They like a good long hike, but they'd just as soon lie on the front step looking unpredictable - it's their eyebrows, I think.