It happens in an instant. We stop the van on a remote forest road and let the dogs out to stretch their legs. Nose-to-the-ground hound dog Scooby investigates every rock and clump of grass near the van, then meanders over to a thickly coiled rope a dozen feet from our tires. The rope fires off a sharp warning rattle. Scooby recoils, terrified. Good dog, Scooby.