Why Do Dogs Have Whiskers?

By Karin Krisher

Dogs’ whiskers are pretty intriguing things. The skin around them starts to gray to give you your first sign that your pup is on the dog side of pup, finally. They accidentally rub against you and give you a tickle on the arm when you’re cuddling. And they just look cute.

So we know why they matter to us humans. But why do dogs have whiskers in the first place? Do they serve some sort of purpose? We’re here to tell you that their purpose is greater than you might have imagined.

What Are They?

Just hairs, right? Wrong.

While whiskers are technically stiff hairs, they aren’t as non-functional as their name implies. To think of them in a way that tells us they’re important, let’s call dog whiskers by their actual name: vibrissae.

Notice anything familiar in that word? Its root is the same as vibration—to move quickly to and fro. And whether or not we see our dogs wiggling their whiskers, vibrations are how we all sense things. So it can be inferred that vibrissae are used for sensing the world. But how?

The Brain Factor

If you really want to identify why a certain part of the body exists, it’s always good to look at its relationship to the brain. How much of the brain does stimulation of that area use? Where is the signal located? Of the parts of a dog’s brain devoted to registering the “touch” signal, 40% is devoted to facial sensation—a large amount of that is devoted to the upper jaw, where vibrissae poke out.

That tells us that these whiskers are pretty important, after all. You could even match individual whiskers with individual reactions in the brain, which indicates a high level of specialization. What could they be telling the brain?

The Information Relay

When you tap the end of one vibrissa lightly, your dog will make that “I’m annoyed” face, which consists of a blink and a head turn. That’s because whiskers tell your dog that something is near his face, and he should do what he needs to protect it. In this case, it’s a simple head turn away from your antagonism.

Another action of vibrissae is to whisk slightly when a dog does turn his head, vibrating to drag across a surface and gain information about that surface, like identifying its texture and shape. This action is important to dogs because other biologic factors might get in the way of this process: dogs don’t have hands; muzzles block their vision; eyes can’t focus if an object is too close. The whiskers, which point down and forward, take over those roles.

That also comes into play when assessing maneuverability. Because dogs don’t have shoulders and their width is relatively similar along the body aside from the head, knowing where their whiskers touch can be valuable to deciding whether or not to continue into a space.

The sheer sensitivity of these whiskers has led to us thinking that dogs have a true sixth sense, though that sense is really touch. Weather patterns, ghosts, air currents in a dark room—vibrations can be another way to see and hear things outside the capability of normal human perception.

Guess what? All of this goes for cats, too. Except for the 40% bit; dogs’ whiskers are seriously wired in.

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