You know the sound of a dog's howl.

That drawn-out, melancholy, doleful noise that makes you picture a wolf, nose raised to the heavens, on a mountain top, mouth open, with a full moon lighting up the night sky. But what does a howl signify? Like most of the noises dogs make, howls can have a variety of meanings.

To Find Pack Members

From a genetic standpoint, dogs are closely related to wolves. In the wild, wolf packs would send out scouts to search for food. The scout would howl to find his pack, and the pack would howl in response. If the scout was overdue, the pack would howl to tell the scout it was time to come home. When your dog hears another dog howl, or even an emergency siren, it may trigger an instinct to howl in response as if to say, "I'm over here. Come join me!"

To Ward Off Intruders

On the other end of the spectrum, your dog may howl as an intruder alert. If a strange dog enters your yard or some other area your dog considers his territory, your dog may howl to alert the stranger that this area has already been claimed.

Result of Separation anxiety

Some dogs handle being alone better than other dogs. If you leave your dog for long periods of time and he misses you, he may howl to bring you back. Dogs have a pack mentality, and in his mind, you are a member of your dog's pack. If he misses you, he may howl so you can find your way home to him. Dogs also can be extremely good at training their humans. If you run to see what wrong every time your dog howls, he'll quickly figure out that if he wants your attention, all he needs to do is howl.

To Indicate Pain

Your dog may also howl to signal he's hurting. Dogs' vocabularies are pretty limited to whimpers, whines, growls, barks and howls. He may be trying to tell you something's not quite right.

To Be Part of the Group

Some dogs seem to just enjoy "singing." If your pup bursts forth in a howl when he hears certain songs, musical instruments, or even other dogs or sirens, he may just be joining in for the sure delight of howling. Despite the mournful sound, if your dog's tail is wagging and his body language is otherwise happy while he howls, he may just enjoy singing along.

Learn to Translate

As with all communication from your dog, you should try to learn what your dog is telling you when he howls. Remember he may not be telling you the same thing each time with his howling. If he's howling in pain, of course you want to get him to a vet or pet emergency center as soon as possible. If he's howling when he's alone, you should address the different avenues you can take to help your dog overcome separation anxiety. Otherwise, don't be too concerned about your dog's howling. It's in his nature and sometimes a dog just has to give into his doggy instincts.