By Teresa K. Traverse
You probably don’t think twice about your dog’s tongue, but it does a lot more than just lick your face.
“The tongue is an essential part of the mouth in a dog,” says Dr. Alexander Reiter, professor of dentistry and oral surgery at the University of Pennsylvania in Philadelphia. Dogs use their tongues to eat, lap water, swallow, and cool themselves down, too.
“The tongue is a muscle,” says Dr. Ann Hohenhaus, a staff doctor at Animal Medical Center in New York City. “Like all muscles, it's controlled by nerves. And in the case of the tongue, the nerves come straight off the brain to control the tongue.”
Here are nine facts about dog tongues that may surprise you.
Some Dogs Have Blue Tongues
Chow Chows and Shar-Peis both have blue or dark tongues, and no one knows exactly why, Hohenhaus says. The link they share is that they’re both Chinese breeds and closely genetically related, she says.
It can be more difficult for a veterinarian to identify certain problems when a dog’s tongue is blue. “These animals are at a minor disadvantage in a veterinarian’s ability to assess health,” Hohenhaus says. “In a dog whose tongue is normally pink, a blue tongue tells us that they’re not oxygenating well.”
In some cases, a blue tongue can be a sign of lung or heart disease or a rare hemoglobin disease, Hohenhaus adds.
Dog Tongues Are Not Cleaner Than Human Tongues
The phrase “licking your wounds” is incredibly common, but letting a dog licks his wounds isn’t actually a good way to help heal a cut. Nor is it true that dog saliva has healing properties for human wounds. While the licking motion of the tongue may help a dog clean an area, the healing properties of canine saliva have never been proven, Reiter says. Another commonly held myth is that dogs have cleaner mouths than humans, but both contain more than 600 types of bacteria.
“That is just this constant myth that people have,” Hohenhaus says. “Nobody would put bacteria on a wound. Why would you put a tongue, which has all this bacteria, on a wound? It doesn’t make sense.”
Dogs Groom Themselves, Too
Cats regularly lick their fur to groom themselves. Dogs also partake in this ritual, but their tongues just aren’t quite as effective at getting the job done.
A lot of this has to do with basic biology. Cats have rough tongues that feel like sandpaper. That’s because the feline tongue is covered in papillae or tiny barbs, which help cats get knots and tangles out while grooming, Hohenhaus says. “A dog is at a disadvantage because it has a smooth tongue,” she says.
Although your dog can use his tongue to help remove dirt or shed fur, you will still need to brush him out to prevent or remove matts and tangles.
Dogs Use Their Tongues to Help Cool Themselves
When dogs pant, it serves as a way to cool themselves. The process is known as thermoregulation. Hohenhaus explains that dogs don’t have sweat glands all over their body like humans do, only on their paw pads and noses. This means dogs can’t sweat through their skin to cool off. Instead, they rely on panting. When dogs pant, the air moves quickly over their tongue, mouth, and the lining of their upper respiratory tract allowing moisture to evaporate and cool them down.
Some Dogs Are Born with Tongues That Are Too Big
“There are some rare situations where puppies are born with tongues that are too large to do normal functions such as suckling at the teat,” Reiter says. This rare condition is called macroglossia. In his 20 years of experience, Reiter has only seen two cases.
Some breeds—like Boxers—are prone to having larger tongues that hang of out of their mouths. This usually doesn’t cause the dog any problems, and doctors can surgically reduce the size of the tongue or recommend other treatments, if necessary.
A Dog’s Tongue May Influence the Way His Bark Sounds
In the same way that your tongue influences the way you speak, a dog’s tongue affects the way he barks. “Any structure in the mouth will to some degree participate in creating voice and sound,” Reiter says.
Think of what happens when you take a glass of wine and run your finger around the rim, Reiter says. The sound will change depending on how much liquid is in the glass. Likewise, the size of a dog’s tongue will affect the sound of his bark. “Most definitely the tongue plays a role in how a bark will sound,” Reiter says, but “the actual bark is made by something different.”
In terms of shape, dog tongues are longer and narrower than human tongues. “A dog tongue is differently mobile in part because dogs don’t speak,” Hohenhaus says. “They don’t need to move their tongue around to [pronounce] the letter S or T.”
Dogs’ Tongues Have Fewer Taste Buds Than Humans
Dogs have more taste buds on their tongue than cats, but not nearly as many as humans. (They have about one-sixth the number of taste buds of humans.) Dogs can taste thing that are bitter, salty, sweet, and sour. Cats, on the other hand, can’t taste sweetness, Hohenhaus says. “But we also think that dogs choose their food more by smell than by taste,” she says. “Smell is more important, and dogs have an incredible sense of smell.” All this suggests that a dog’s sense of taste is less sensitive than a person’s, Hohenhaus explains.
Dogs Use Their Tongues to Express Emotion
Many dog owners know how nice it can be to get “kisses” from their dogs. But it can be difficult to interpret exactly what a dog licks means, according to the experts. Hohenhaus says it’s probably a dog’s way of exploring his environment, in the same way that babies do with their mouths. “Dogs use their tongues to lick other dogs’ faces during times of happiness and excitement,” Reiter adds.
Be cautious about letting your dog constantly lick your face, though. “There is some research that bacteria causing periodontal disease can transfer from dogs to humans,” Reiter says.
Dogs Drink Water Differently Than Cats
Dogs and cats both use their tongues to drink water, but the process is very different. A cat uses the tip of his tongue to pull water upward and then quickly snaps his jaw shut to catch the liquid in his mouth. A dog uses “a simple lapping process with the tongue curled slightly backward to form a ‘spoon’ that collects as much water as possible and quickly puts it back into their mouth,” Reiter says. Check out this video to see the difference.