Dogs are so furry that even the most observant of owners can miss details about their appearance. Take dog whiskers, for example. They’re usually visible above the eyes and on the muzzle, but did you know that your dog likely has a tiny beard of whiskers below its jaws? If you examine this area on your pet, you should notice some dark skin sprouting a hair or two. That colored skin resembles what we call a beauty mark in humans. On your dog, it’s actually a collection of nerves, and the thick hairs that sprout from it are not just fur. These whiskers are called “vibrissae,” and like top-secret FBI tools, they allow your dog to investigate everything from you to your home.

The hidden power behind your dog’s vibrissae is their sensitivity. They are extremely receptive to touch. Unlike fur, they have functions other than just keeping your dog warm or cold. They’re designed to transmit detailed information about movement to aid your dog’s guidance and balance.

A few years ago, veterinarian Sophia Yin took her Australian cattle dog, Zoe, to a horse ranch and let the dog sleep in the stables overnight. In the middle of the night, Dr. Yin was startled by a strange, loud howling sound. "It sounded like the loneliest dog in the world," recalls Dr. Yin, DVM, a certified applied animal behaviorist who works at San Francisco Veterinary Specialists. She then realized it was her own pet, Zoe. “She thought she had been left and abandoned,” Dr. Yin recalls.

Your dog may howl when you least expect it -- as you’re warbling a tune at the piano, when a fire engine siren sounds or if your dog is left alone in a strange place. Howling may not be music to your ears, but to your pooch, it is a throwback to its wolf instincts. The purposes, meanings and triggers of howling may surprise you.