Why do dogs click their tongue

Source: Sarah J. / Creative Content License

When the Nobel Prize-winning ethologist Konrad Lorenz forced a dog to lie flat on the floor in a submissive position, the dog stopped struggling, went slack, and then flicked its tongue as if it was licking its lips or the air. While most dog owners tend to look at all forms of licking by their pets as being signs of affection, Lorenz recognized that in this situation the dog's behavior had a totally different meaning. Some new research now shows that when dogs are stressed, perhaps by recognizing negative emotional states in others, it may trigger this form of non-social contact licking.

Over the past few decades, researchers have begun to recognize that a dog's licking behavior can communicate information about dominance, intentions, and state of mind. The current consensus is that lip or air licking is mainly a pacifying behavior. One thing in common among all pacifying signals is that they contain elements of puppy-like behavior. Juvenile behavior is the canine equivalent of a "white flag." Most adults tend to nurture the young of their own species and there appears to be a strong inhibition against actually attacking them.

Thus, non-dominant, frightened or weak adults will adopt puppy-like postures and perform juvenile actions to avoid aggression. These behaviors usually soften the mood of the threatening animal and will normally avert any sort of physical attack. Many aspects of pacifying behavior contain forms of licking and it makes sense to look at the actions of young puppies to interpret what these signals were meant to communicate in their earliest stages.

As puppies mature in their litter, they begin to lick and clean themselves and their littermates. This mutual licking and grooming serve several social functions. Obviously it helps keep the puppies clean, but in the process, it helps to strengthen the bonds between the puppies. The actual mechanism that builds this affection is mutual satisfaction. A puppy can thus have companions to get at those hard to reach places, like ears and backs and faces and they can pay them back by licking their littermates in their inaccessible regions.

Because friends and familiars groom friends and familiars as a considerate gesture, the very act of licking another dog develops significance as a means of communication. Licking thus shifts from being a utilitarian and useful act to becoming a ritualized gesture. The meaning of this gesture at this time in a puppy's life involves goodwill and acceptance. In effect, each puppy is saying something like, "Look how friendly I am." As the puppy matures, the message sent by licking continues to be friendly but is widened to also mean, "I am no threat," and perhaps also the submissive plea, "Please accept me and be kind."

Licking takes on another meaning a little bit later in the puppy's life, usually around the time that they become less dependent on their mother's milk. In the wild, when a mother wolf returns from hunting she will have already fed herself on her quarry. When she enters the den, the puppies gather around her and begin to lick her face. To a romantic, this may look like a loving greeting with all of the puppies overjoyed at the mother's return after her absence of several hours. They are seen as simply kissing her in happiness and relief.

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The actual purpose of all of this face-licking, however, is really much more functional. Wild canines have a well-developed regurgitation reflex and the puppies lick their mother's face and lips to cause her to vomit up some food. It is most convenient for the mother to carry food in her stomach rather than trying to drag things back to the den in her mouth. Furthermore, this partially digested material makes ideal dining for young puppies. This puppy induced regurgitation is not as often seen in domestic dogs unless the pups are not being well-fed.

Understanding the development of licking behavior helps to interpret another place where it occurs. Face-licking in adult canines can be a sign of respect or deference to a more dominant dog. The dog doing the licking usually lowers his body to make himself smaller and looks up, adding to the effect of juvenile behavior. The dog receiving the face-licks shows his dominance by standing tall to accept the gesture but does not lick the other dog in return.

It is often a stressed and fearful dog who is exhibiting licking behavior and these behaviors have become so ritualized that an anxious dog may lick even when there is no dog or person close enough to be licked. It may lick its own lips, much like stressed humans may bite their lip. Sometimes the dog will simply extend its tongue quickly and appear to be licking the air. At other times the dog may drop down to the floor and nervously lick at its own paws or body.

I frequently see this kind of lip-licking or air-licking on the first day of a beginner's dog obedience class. The dogs are often stressed because their handlers are a bit nervous, the surroundings are strange and there are unfamiliar dogs in the room. As the classes proceed, however, the room, the situation, and the other dogs all become familiar, and the licking behavior quickly disappears. I have been told by veterinarians that they often observe the same behaviors in their consulting rooms. The dog licks the air and its lips while it seems to fret about this new environment, filled with strangers and unknown future events.

Some new research indicates that simply recognizing negative emotions in other dogs or people can trigger this kind of licking behavior. The research team was headed by Natalia Albuquerque from the School of Life Sciences at the University of Lincoln in the UK. The dogs used in this study were pet dogs of various breeds. The investigators presented the dogs with photographs of unfamiliar human or dog faces displaying different types of emotions (in this case happy or playful faces versus angry or aggressive faces). The pictures were presented side-by-side and the scientists videotaped which pictures the dogs looked at and what reactions the dogs displayed.

The results show that roughly one out of every five times when the dogs were presented with a canine or a human face showing an angry or aggressive expression, it would trigger a lip-lick or an air-lick from the dog. The investigators interpret this as an indication that seeing such a negative emotional image produced a momentary, low level, stress response in the dog. This mild stress or anxiety was enough to trigger an involuntary quick lick from the dog. They conclude that this confirms that such licking behavior represents an expression of worry or concern on the part of the dog.

There was one interesting quirk in these data. When confronted with a negative facial expression in a human being the dogs were twice as likely to lip-lick or air-lick than they were when confronted with a negative expression from another dog. This is a puzzling finding, for which the researchers really don't have a clear explanation.

However, one speculative possibility is that humans are much more responsive to facial expressions than are dogs. A subtle gesture like a tongue flicking out of the mouth is more likely to be recognized and responded to by humans rather than other canines. If that is the case then as dogs and humans co-evolved that gesture would come to be more likely to be given when the dog's anxiety was triggered by something associated with people. But of course, that is pure speculation.

What is not speculative is that it now appears clear that air-licking and lip-licking in social situations are signs that a dog might be feeling worried or anxious.

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission.

References

Natalia Albuquerquea, Kun Guo, Anna Wilkinson, Briseida Resende, Daniel S. Mills (2018). Mouth-licking by dogs as a response to emotional stimuli. Behavioural Processes, 146, 42-45. doi.org/10.1016/j.beproc.2017.11.006

Adrienne is a certified dog trainer and former veterinarian assistant who partners with some of the best veterinarians worldwide.

Does your dog lick his lips a lot? There are several possible explanations, including thirst, anxiousness or irritated stomach.

Image by Pezibear from Pixabay

You are trying to rest but can't fall asleep because your dog is loudly smacking his lips over and over. What gives?

You get up and offer him some water. Yet, after drinking a bit, your dog's annoying lip-smacking is back. It's almost as if he had peanut butter stuck to the roof of his mouth.

• In a normal scenario, a dog licks his chops repeatedly when he's hungry. If you show a dog a tasty treat or are preparing his meal, you'll likely hear him smacking his chops. In this case, your dog is drooling, and the lip-licking prevents little dribbles of saliva from pouring out of his mouth. He licks his lips because food is around.
• Dogs also lick their lips when they are stressed or uneasy. Usually, this is a very fast lip-lick. It may be almost imperceptible. This is known as a calming signal, as it appears most often when a dog is uncomfortable and under pressure. It's similar to that fast, nervous lip-lick you may see from a politician when he's asked a difficult question. You'll likely see this type of lip-licking if you scold your dog, after another dog growls at him or when he is startled.

What do both these scenarios have in common? There is a visible explanation for the lip-smacking behavior. The behavior occurs in precise circumstances and not out of context. Coming up, we will address some possible causes for out-of-context lip-smacking, when a reasonable explanation cannot be found.

Six Causes of Lip-Smacking in Dogs

Of course, these are only some possible causes. Keep in mind that only a veterinarian can diagnose the problem with absolute certainty.

1. Something Is Stuck in Your Dog's Mouth

A good place to start is to carefully inspect your dog's mouth if your dog allows it. Sometimes a piece of a stick may be caught somewhere, there may be a bad tooth, or your dog may have gingivitis (a bacterial infection). Both can cause drooling and lip-smacking. If you're not comfortable inspecting your dog's mouth, see your vet.

2. Nausea and Digestive Upset

When the dog feels nauseous, he may drool and smack his lips as he gulps down saliva. If the dog is sent out, he'll often try to eat grass. If this is not possible, he may frantically lick other available surfaces, including carpets and walls. If he vomits, the nausea and lip-smacking will probably subside.

If your dog seems to become nauseous at night, it may be that excessive bile is building up in his stomach. Some dogs will smack their lips a lot before vomiting yellow bile at night or in the early morning. A late-evening snack can help prevent this condition. More severe cases may require antacid medications.

3. Discomfort or Pain

In some cases, lip-smacking is a response to pain. Has your dog been limping recently? Does he have some sort of orthopedic disorder? Perhaps neck pain? Does he yelp if you touch him in a certain area? It can quite difficult to pinpoint exactly where the pain is located in a dog. Your vet may be able to figure it out.

4. Dehydration and Dry Mouth

When a dog is dehydrated, it may smack its lips to wet its gums. A good way to assess for dehydration is to lift the skin over the dog's shoulder blades and back. If it immediately springs back, then your dog is still well hydrated. If there is a delay, check your dog's gums. If they are dry and tacky, then your dog is dehydrated. Depending upon the severity of the problem, they will need to be hydrated either orally, subcutaneously, or intravenously.

5. Nervous System Disorder or Seizure

If your dog ingested something toxic, it might affect its nervous system. This can lead a dog to lick its lips excessively. For example, if a dog ingests any part of a poisonous toad, the dog may immediately start to drool, lick his lips, and foam at the mouth. In some cases, even exposure to bitter-tasting substances can make a dog lick their lips over and over. Finally, some types of partial or simple seizures can lead a dog to excessive lip-licking.

6. Salivary Gland Problem

A dog's salivary glands can swell, causing what is called a sialocele. When this happens, the saliva pools in the mouth and doesn't flow normally. It can cause the dog to lick their lips to move the saliva around their mouth normally. Look under your dog's tongue where the salivary glands are located. If you see any swelling, see your vet. This condition can be resolved with a simple surgical drain.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2013 Adrienne Farricelli

Comments

Adrienne Farricelli (author) on October 15, 2017:

Does this happen mostly when she's been on an empty stomach? Some dogs accumulate bile when their stomach is empty for too long and this causes them to vomit bile. Sometimes feeding a snack every now and then helps. Consult with your vet on this to get to the bottom of it.

Eileen Costello on October 12, 2017:

My 16yr old X jack Russell SLAPS her tummy quite aggressively

Amanda Davidson on October 11, 2017:

I have a question! I have noticed that my 10 year old dog who's a pug and Chihuahua mix seems to lick lip smack excessivly when A. She's going to be sick which if she does vomit it's Yellow liquid! ! Or B. When she Needs to go out and poo! What in the Entire World could do that to my baby? And Why? Any possible causes or explainable reasons? Anything I can do to help her? She is my entire world!! I love her Soo much I see her go to be sick I just want to cry! But I can't turn my back on her if she's sick!!! I go stay beside her and try to comfort her I just don't see why needing to go poop would make her vomit bile and smack her mouth!?! Should I be Worried!??? Thank you!

Adrienne Farricelli (author) on March 07, 2017:

If his breath is so bad, it could be he is smacking his lips because of excess salivation due to some problem in his mouth.

Domenic DeCesare on March 01, 2017:

So my dog is a rescued German Shepherd. He has had stomach issues since i got him and needs a hip replacement. ive tried him on all different diets like Orijen, Fromm, and now Primal Raw. His energy level is getting better on the raw and he is more playful but before starting the raw his occasional gross wet licking sounds and weird tongue movements werent nearly as bad as they have gotten lately. its not the raw cuz he was actually doing this right before putting him on the raw. i have had over 40 biopsies taken of his esophogus down to his colon and showing nothing. Im wondering if with him it has to do with his teeth or gums. He may not be chewing food causing stomach issues but if there was a small infection that is growing that could cause this. his breath is putrid now when before it was thought to be stomach acid that wasnt draining from his duodenum. now i gotta get his teeth looked at cuz i can sometimes smell when he yawns across the room. sweetest dog, and he has been riddled with problems since i rescued him. i cant even get his hip replaced until his stomach issue is sorted out according to Ohio State Veterinary Center :( hopefully the oral exam will stop this gross symptom

Adrienne Farricelli (author) on February 21, 2017:

Amanda, how old is your dog? And how early do you remove the water?

Amanda Abbott on February 15, 2017:

Great resource for me! Woke up late at night because my dog was licking and smacking his lips. I gave him water and it stopped. I usually take his water up at night to prevent any accidents. Am I wrong to do this?

Adrienne Farricelli (author) on January 16, 2017:

Brandy, lip smacking and lip licking are soooo close to one another. They actually often occur at the same time often. Try to lick your upper lip with you tongue, Most likely, you'll get a smacking sound. Lip smacking is just the noise produced when the dog uses his tongue to lick his lips and sometimes tip of his nose. It's a more significant type of lip lick. If it's happening when being told to sit or stay down it could be a calming signal or an anticipation for a treat to lick away a bit of drool.

Adrienne Farricelli (author) on January 14, 2017:

Sounds like some form of digestive upset like too much build-up of acid. I would discuss that with your vet.

Baishali Manna on January 13, 2017:

My dog's breed is Spitz n she's 6yrs old.

Sometimes she smacks her lips again n again, n she does it in quite a fast manner.

She seems uneasy n runs all around in the house, attempting to go outside.

She smells the ground, licks the soil in the garden n starts eating leaves (particularly basil leaves in our garden).

Not necessarily she vomits every time. But she seems restless. What may be the reason n how to prevent it?

Brandy on January 11, 2017:

I am a little confused.

Are the terms lip smacking, and lip licking being used interchangeably here, or am I misunderstanding?

My boxer specifically smacks his lips when being told to sit, or stay down.

He is not licking his lips.

This is the 3rd article I have read about "lip smacking", and I have more questions than I had when I started, because every article seems to be using the terms interchangeably.

Adrienne Farricelli (author) on November 24, 2016:

Cheryl, inform your vet about your dog's lip smacking. Perhaps he's no longer chewing his food and he's having digestive issues?

Cheryl on November 20, 2016:

My fog had all of his teeth pulled and 3 months later he started doing the lip smacking???! Not sure why! He's not sick and drinks plenty of water

Adrienne Farricelli (author) on January 15, 2016:

Maybe see the vet to just rule anything medical out? Some dogs are reluctant to lie down because they have abdominal pain. If this is a new behavior, it could be medically related , something to rule out just in case.

Andrew on January 07, 2016:

My pit doing this at night is one of the most obnoxious things to me. I want her to stop but I have no idea how to go about it since she doesn't exactly understand English. She will do it pretty much every night when I let her up on the bed to sleep. She'll jump up and get next to me, but instead of laying all they way down she will do this awkward sulking posture where she keeps her front legs extended with her head facing down as if she's a sad beaten step child. (I've had her since a pup and I have never beaten her as discipline btw) When I tell her to lay down all the way she will sigh/grumble and hesitantly flatten out. This is when she will start the God awful lip smacking and teeth clicking every couple seconds that she will continue to do for a good 5 min. What gives? She seems nervous or resistant to getting comfortable even though she came to the end of the bed to stare at me obviously wanting up. I don't think any of the things mentioned in the article because she's happy and healthy throughout the day. Do I just have to accept this as part of her going to bed ritual?

Adrienne Farricelli (author) on May 12, 2015:

Hello bob, it depends on what is causing the lip smacking behavior in the first place.

bob on May 11, 2015:

Can it be stopped

Adrienne Farricelli (author) on January 15, 2015:

Dogs are so interesting, they each seem to have their own personalities! Thanks for sharing your story, it adds another reason for dogs smacking their lips that wasn't included in the article.

samsowner on January 15, 2015:

I have a yellow lab. He smacks his lips as a form of talking. Whenever I am petting him he is fine, but if I start talking to him, he starts smacking his lips. Sometimes when I stop petting him, he will look at me and smack his lips. It's really annoying, but I guess better than barking!

Adrienne Farricelli (author) on June 10, 2013:

Thanks for stopping by epbooks. Sounds like a displacement behavior,

https://pethelpful.com/dogs/Understanding-Dog-Disp...

Elizabeth Parker from Las Vegas, NV on June 10, 2013:

Excellent hub. I've also noticed my dogs will nibble on their legs if they are feeling uncomfortable or stressed. Usually distraction helps them and they forget all about what is disturbing them. Thanks for writing!

Agnes on May 16, 2013:

That's great idea. I did not think of it! I was always trying to give him water to drink, but he didn't want it.

Adrienne Farricelli (author) on May 15, 2013:

Monis Mas, my dogs do that too prior to vomiting, they smack their lips, drool ans swallow a lot. Sometimes though I noticed it happened when my dog swallowed something that was irritating her throat and giving her bread helped her feel better.

Andreea Cojocariu from Atlanta, GA on May 14, 2013:

Did not know it was a sign of pain! Good to know!

Agnes on May 13, 2013:

Excellent infirmation. MY doggie does it, when he doesn't feel well, and is about to vomit. I have some time to grab a newpaper or take him on a tiled floor!

Eiddwen from Wales on May 13, 2013:

as always another truly interesting hub for all dog owners.

Eddy.

Adrienne Farricelli (author) on May 12, 2013:

Thanks for stopping by MJennifer! I wrote this also because my girl Rottie who is recovering from a torn cruciate ligament started doing it as well at night, right when I tried to lower the dosage of her pain meds and my vet once mentioned this can be due to pain. I think at night the home is also quiet and just like us, dogs concentrate on their pain more during this time. My horse used to "flehem" every time I offered him honey for some reason, so I sometimes used that to my advantage to get great pictures of him "smiling!"

Marcy J. Miller from Arizona on May 12, 2013:

Excellent hub, Adrienne. One of my furries has a significant lip-smacking habit, particularly at night, that I have ascribed to the discomfort of his spondylosis. During the day, he's extremely happy and active, and we've made great strides in his treatment -- he's doing better than he was three years ago, if you can imagine -- but I believe that at night, when he's not moving about as much, his achy bones catch up with him.

I've also noted the "tonguing" you mention in our youngest member of the pack, the McNab. You've described it perfectly. He does it when he's just sniffed the sole female's rear -- and he looks possessed when he does it. I never made the connection to the flehmen (which I see in my horses). Very interesting.

I'm glad you thought to write on the subject, since I haven't seen it covered anywhere before!

Adrienne Farricelli (author) on May 12, 2013:

Thanks for stopping by, sounds like you are describing a "flehmen response" which is seen a lot in felines, but not so often in canines. In canines it is known as " tonguing" as the tongue is pushed back and the dog may foam at the mouth a bit while his teeth chatter. This is often done upon smelling a urine spot for the reasons you explained.

Bob Bamberg on May 12, 2013:

That's a behavior observed in cats, too, alexadry. I'd be pushed back in my recliner and my cat would jump up, sit on my chest and sniff my mouth. Then she'd engage in that lip smacking. It's a way to direct molecules of scent to the vomeronasal organ in the roof of the mouth. It would gross me out...it's really an unpleasant sound (to me, anyway). Good information, voted up, useful and interesting.