No offense to canine lovers, but not all dogs are smart enough to lead humans out of danger, a la Lassie and the fire at the Old Mill. Truth be told, some have trouble just staying near their owners.
So if your four-legged best friend has a habit of wandering off without you, something like the "Pet Tag Flasher" might be worth considering. When worn around the neck (the dog's, not yours), it flashes four red LEDs to help identify the pet's whereabouts in a street crowd or even a packed watering hole because it's waterproof, according to Uber-Review.
But if you have the opposite problem and Rover won't keep his trap shut, there's always the "."