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Watch a dog panting during a hot day, and it's almost impossible to ignore how long a dog's tongue is compared to the tongue in humans. This is ultimately not surprising, considering the importance of this body part when it comes to a dog's health and overall well-being. 

For those wondering, the average length of the human tongue is about 3 inches. Dogs obviously have much longer tongues and there are several good reasons behind this feature. 

You're not imagining things if your dog's tongue looks larger when your dog is hot

You're not imagining things if your dog's tongue looks larger when your dog is hot

A Dog's Radiator

In humans, sweating is the primary way to cool down, there's no bones about that. When a person’s brain senses that his body’s internal temperature is starting to rise, the sympathetic nervous system kicks in activating the body's sweat glands, which ultimately leads to sweating. 

While in humans sweat glands are developed over large areas of the skin surface, in dogs, sweat glands are only limited to the foot pads; however, these glands do not play a significant role in cooling dogs down. Rather, dogs mainly cool themselves down by panting. 

When panting, dogs are able to cool down courtesy of the surface area of their tongues. Here, upon the dog breathing quickly and shallowly, the air passes over the tongue. Next, saliva evaporates and blood circulating through the tongue cools down, circulating back to the rest of the dog's body, ultimately cooling him down, explains veterinarian Dr. Wendy C. Brooks in an article for Veterinary Information Network. 

Of course, a larger surface area grants a more efficient cooling system so a longer tongue comes extra handy, so don't be surprised if Rover's tongue looks longer and larger after going for a run!

Here's what's happening: when a dog overheats, his tongue tends to increase in size for the purpose of accommodating more blood which can be cooled down further through contact with the air, explain Caroline Coile and Margaret H. Bohman in the book: "Why Do Dogs Like Balls? More Than 200 Canine Quirks, Curiosities and Conundrums Revealed." The end result? You got it. A much cooler pooch, in the dog days of summer.

 A Grooming Device

Deprived from hands, dogs rely on their long tongues to reach areas that would be difficult or close to impossible to reach otherwise. Next time your dog engages in a grooming session, watch him carefully.

That long tongue allows your dog to reach right in between each toe, and when he flips his body, head-to tail, with the agility of an acrobat, he is able to reach his private areas courtesy of the length of his tongue.

And when your dog suffers from a runny nose, it's not like he can grab a tissue and just forcefully blow his nostrils! Dogs though have their own canine way of getting rid of annoying nasal secretions and this method can be so efficient that you may hardly never know when Rover's nose is actually dripping.

First of all,  consider that dogs are very attuned to the sensation of any mere watery secretions. The moment they sense a little trickle, it is quickly wiped off with a quick flick of the tongue. You may barely notice this, as it happens so quickly, but if you take a look at the picture below you can see how easily a dog's tongue can reach each nostril to wipe off any discharge.


A Ladle of Water 

Not too long ago, the exact mechanisms of how dogs lapped up water were finally revealed. All it takes to understand the mechanism is watching a slow motion video as the one below. Here's a summary of what happens exactly. 

When your dog approaches the water bowl and lowers his long tongue to drink, it curls up and pulls up a small pocket of water which is stored underneath the tongue, and then inserted into the mouth like a ladle. 

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This may seem like an inefficient way for dogs to drink compared to our strategy of gulping water from a glass, but there's an evolutionary reason as to why dogs drink this way. 

Albeit slow, this method of drinking allows dogs to keep their eyes up and look around. This way they can keep an eye on any prey or predator around them, explains veterinarian Dr. Justin Lee in the book "It's a Dog's Life...but It's Your Carpet, Everything You Ever Wanted to Know About Your Four-Legged Friend."

A long tongue therefore allows dogs to use it like a handy ladle. This adaptive drinking strategy prevented them from slurping up water with their head angled which, back in the days when dogs literally lived in a dog-eat-dog world, could have potentially been costly if a predator happened to be nearby.

Did you know? According to an ancient legend by Southeastern Native American tribes, dogs have a long tongue because Running Water, who was a great hunter, grew tired of his dog's tattling (back in time when dogs were considered like people and talked), so he caught hold of his dog's tongue and pulled as hard as he could, leading to why dogs have long tongues today. 

Hanging Tongue Syndrome in Dogs 

Something worthy of mentioning is a curious condition known as "hanging tongue syndrome." As the name implies, affected dogs have a long tongue sticking out, but this is due to something medically going on. 

The tongue may be sticking out because the dog has lost his lower canine teeth, which used to keep the tongue in place or the dog may have sustained some type of trauma to the jaw or nerves responsible for holding the dog's tongue in place. 

Did you know? Chinese crested dogs often have a tongue hanging out. This is because most Chinese crested dogs have numerous missing teeth. This peculiarity is what often causes Chinese crested to win the title of Ugliest Dogs. 

Chinese crested dogs often have a tongue hanging out.

Chinese crested dogs often have a tongue hanging out.

Now That You Know...

As seen, there are several great evolutionary reasons as to why dogs are blessed with long tongues. The next question though is: with such a long tongue, can dogs ever bite it? This question makes perfect sense, considering how tongues are in a vulnerable position right in the middle of a dog's sharp teeth!

  We might not know yet exactly what mechanism prevents dogs from biting their tongues, but in mice, a study has shown that special premotor neurons, responsible for controlling jaw and tongue muscles, play a role in preventing the mouth from closing unless the tongue is simultaneously retracted. Quite fascinating, huh?

However, as with all thing in life, not everything is fool-proof. When dogs play vigorously , biting the tongue is not all that uncommon considering how a dog's long tongue is often out and "in the way".

 Fortunately though, tongue injuries among dogs heal very well because the tongue has an excellent vascular supply, explain Dale Kressin and Steve Honzelka, two board-certified veterinarians specializing in animal dentistry. 

Did you know? The longest tongue belonged to Brandy, a boxer whose tongue measured an astounding 1 foot 5 inches. Another Guinness World Record for the longest tongue belonged to Mochi “Mo” Rickert, a female St Bernard from South Dakota whose tongue measured an impressive 7.3 inches!

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