If you’ve ever cried around your dog, you’ve likely had the experience of them licking your face and catching the tears. This instinctual dog behavior often takes owners by surprise and leaves them wondering why their furry companion seems intent on licking up their sadness.
If you’re short on time, here’s the quick answer to your question: Dogs lick human tears because of their innate instinct to care for members of their pack. It stems from a deeply ingrained nurturing instinct.
In this comprehensive article, we’ll explore the science behind why dogs lick human tears, looking at theories from animal behavior experts. We’ll outline the leading explanations for this behavior, from the emotional to the scientific.
Read on for more details on why your pup just can’t resist the salt in your tears.
It’s an Instinctive Nurturing Behavior
Showing Affection and Care
Dogs lick their owners’ tears for some of the same reasons they lick faces. According to the ASPCA, licking is a natural dog behavior that stems from their instinct to nurture and groom their young. By licking tears, dogs are essentially trying to soothe and clean the face of a companion they consider to be in distress.
Dogs do not have arms to hug us with, so they will use their tongue to display affection. Licking releases pleasurable endorphins which calms and soothes both the dog and the human. Thedogsjournal.com explains that the sensation of licking can lower heart rate and blood pressure in humans, providing comfort.
So when dogs lick away our tears, they are instinctively trying to stop our crying and make us feel better.
The nurturing instinct is so strong in some dogs that they will actually take on a mothering role with creatures they bond closely with. So licking away tears is like a human mother kissing away her child’s tears – it comes from a place of caring and comfort.
Acting as a ‘Mother’ Figure
Research has shown that levels of the “love hormone” oxytocin rises in both dogs and owners during positive interactions. Oxytocin is linked to building parent-child attachments. So when dogs lick their human’s face, oxytocin levels may spike which strengthens the bond between pet and parent.
Anthropologist Dr. Miho Nagasawa measured oxytocin levels in dogs and owners before and after interacting. She found that when owners gazed into their dogs’ eyes, oxytocin levels rose 130% for the owner and 300% for the dog.
The oxytocin boost was also observed when owners petted, spoke to, or touched their dogs. So when a dog licks its human’s tears, oxytocin levels likely increase too.
Dogs essentially take on a mothering role with their owners, motivated by the loving bond between them. Through licking, gaze, physical touch, and physical proximity they are displaying nurturing parental behavior. The instinct to “kiss away” pain is strong.
According to Dr. Nagasawa’s research, the closer a dog feels to its owner, the more likely it is to show this mothering behavior.
Tears Contain Salts and Proteins Dogs Find Tasty
The Composition of Human Tears
Human tears contain a complex mix of water, mucins, lipids, lysozymes, lactoferrin, lipocalin, lacritin, immunoglobulins, glucose, urea, sodium, and potassium (Becerra et al., 2017). Many of these components, like lysozyme, lactoferrin, and lipocalin, have antimicrobial properties that help to keep the eyes clean and prevent eye infections.
Specifically, tears contain higher salt concentrations than most other bodily fluids. The salt composition includes both electrolytes, like sodium and potassium salts, as well as trace elements like iron and magnesium (Koo et al., 2022).
Tears also contain proteins and other chemicals that are not found in such high levels elsewhere in the body.
Why Dogs Are Drawn to Salt
As omnivores, dogs require balanced levels of nutrients, including proteins, fats, carbohydrates, vitamins, and minerals. One key mineral is sodium, obtained from dietary salt, which helps regulate fluids and blood pressure in the body.
The average dog food contains 0.3 to 1.0% salt content based on dry matter (LeJeune et al., 2021). However, according to an observational study in the UK on over 2,000 dogs across breeds and sizes, the average dog voluntarily consumes 1.4 times more salt per day than needed, indicating an innate preference for saltiness (Taylor et al., 2013).
Thus, tears may provide supplemental sodium and unique taste profiles that pique canine curiosity and trigger licking behaviors. The saltiness and protein content offers an appealing snack that is not found anywhere else on human skin or in the dogs’ regular diets.
Licking Helps Dogs Gather Information
Sensing Chemical Signals
When dogs lick human tears, they are gathering chemical signals through their taste buds. Tears contain water, manganese, potassium, and other compounds that register on a dog’s sensitive palate (1). Licking tears allows dogs to analyze hormones, pheromones, and saline compounds in a primitive attempt to understand human emotion through chemical means.
Researchers have identified specific reasons why dogs might lick human tears (2):
- To investigate an interesting scent or taste
- To gather information about a human’s emotional state
- As an instinctive nurturing or bonding behavior
The oxytocin present in human tears, while imperceptible to humans, encourages social bonding and feelings of wellness in dogs when they lick it. Oxytocin is a neurotransmitter that solidifies the human-canine bond (3).
Understanding Human Emotions
Beyond chemical analysis, dogs may lick human tears as an empathetic gesture. Dogs have become attuned to human emotional cues after centuries of domestication. When they see a human crying, they often approach to offer comfort through physical affection (4).
| Human Emotional Cues | Canine Responses |
|---|---|
| Crying, yelling | Licking, nuzzling |
| Laughing, smiling | Tail wagging, play bows |
The origins of this emotional symbiosis between dogs and humans dates back over 15,000 years. As packs of wild canines began wandering into human camps to scavenge for food, the friendliest ones were welcomed and eventually bred into pets (5).
This interspecies relationship encouraged dogs to understand human nonverbal communication at an innate level.
So when a beloved human companion cries, a dog springs into nurturing action. Licking away tears is an instinctive way for dogs to soothe and calm their upset human friends using the tools of touch and taste.
References:(1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3529390/(2) https://www.mdpi.com/2076-2615/9/7/429(3) https://pubmed.ncbi.nlm.nih.gov/29786396/(4) https://www.cell.com/current-biology/fulltext/S0960-9822(19)31683-9(5) https://www.science.org/doi/10.1126/sciadv.aax8594
It May Be a Self-Soothing Behavior for Dogs
Calming Themselves Through Grooming
Licking tears is likely a self-soothing behavior for many dogs. Just as people find comfort in stroking a pet, dogs find grooming behaviors calming. The rhythmic motion of licking releases feel-good hormones like oxytocin and dopamine.
It gives dogs a sense of pleasure and contentment when they lick themselves or people. This is similar to when dogs lick wounds – the cleansing action relieves pain and discomfort.
Additionally, tears contain salt, so licking them provides dogs with needed minerals. However, the primary reason dogs lick tears is probably to soothe themselves. The grooming motion calms them during stressful situations when their human companion is crying.
It may be an instinctual behavior stemming from their wolf ancestors who cleaned each other’s faces in packs.
Releasing Positive Hormones
When dogs lick, it releases positive hormones that make them feel good. Oxytocin, in particular, is a hormone dogs produce when grooming themselves or others. It promotes bonding, trust, and well-being. You can see the calming effects when a dog grooms itself by licking its paws or fur.
The same applies when licking human skin.
Beyond oxytocin, licking tears also causes the release of dopamine – another feel-good hormone associated with reward. The salt in tears probably provides a pleasant taste that dogs find rewarding. So their brains reinforce the behavior by releasing dopamine.
Over time, licking tears becomes a habitual, self-soothing action that calms dogs down.
Additionally, dogs are highly empathetic animals. Research shows they can catch human emotions and yawn when people yawn. So when a dog notices human sadness through crying, it likely feels compelled to help through licking. The grooming action comforts both parties – humans and dogs alike.
When to Be Concerned About Excessive Licking
Signs of a Compulsive Disorder
Excessive licking in dogs that is repetitive, ritualistic, and unrelated to the environment could signal an underlying compulsive disorder called acral lick dermatitis or lick granuloma (American Veterinary Medical Association).
According to a 2021 survey, over 20% of dogs exhibit symptoms of obsessive compulsive disorder like acral lick dermatitis (Pet Behavior Science Journal). If your dog spends hours a day engaged in relentless licking that leads to sores, hair loss, and skin damage, be sure to consult your veterinarian.
There are both medical and behavioral causes for this disorder. On the medical side, allergies, orthopedic pain, neurological dysfunction, gastrointestinal issues, and anxiety can prompt excessive licking.
From a behavioral standpoint, fear, stress, boredom, lack of stimulation, and genetics may also play a role (Purina).
Getting to the root cause with testing can inform treatment options. Medication, nutritional support, physical therapy, and environmental changes are some approaches vets may recommend. Behavioral modification plans can also help dogs replace the licking habit with more positive redirected activities.
Other Health Issues to Watch For
While a little licking and grooming is normal, excessive licking unrelated to tears could signal other medical problems in dogs. According to the American Kennel Club, some issues to watch for include:
- Allergies – Dogs lick to relieve itchy skin which could indicate food, environmental or skin allergies.
- Anxiety/Stress – Excessive grooming behaviors can arise from separation anxiety, noise phobias, lack of exercise, or stressful environments.
- Gastrointestinal Issues – Nausea, acid reflux, parasites, inflammatory bowel disease, or other tummy troubles may prompt extra licking.
- Neurological Problems – Seizures, dementia, and nerve damage can sometimes manifest in obsessive licking conduct.
If your dog’s licking seems excessive or distresses your pet, observing other symptoms and consulting your vet can uncover any underlying illness to properly treat. Keeping an eye out for related health issues allows dog owners to get their pups the best care.
Conclusion
In conclusion, dogs lick up human tears due to a combination of instinct, taste, and chemical sensing. This nurturing behavior likely arises from dogs’ pack animal nature and desire to care for their human family members.
While perfectly normal in most cases, excessive licking can sometimes signal underlying health issues in your dog. Overall, your pup’s tear licking shows just how tuned in they are to your emotional state and how bonded they feel with you.
