Why do dogs lick their owners?

31 January 2024

📌 HOME FOOD Blog: Why Do Dogs Lick Their Owners?

Why Do Dogs Lick Their Owners?

Dogs are amazing creatures that communicate with us not only through looks or tail wags but with a whole arsenal of behavioral gestures. One of the most common and heartfelt is licking. Many owners see it as a sign of love, but behind this gesture lies much more: from natural instincts to complex emotional mechanisms and even signals about health. In this blog, we will explore why dogs lick their owners, what exactly they are trying to tell us, and when this gesture should be considered normal and when it warrants closer attention to the behavior.

Evolutionary Mechanisms of Licking: How Ethology Explains It

From the perspective of ethology—the science of natural animal behavior—licking has deep evolutionary roots formed long before dogs became pets. One of the first to systematically study such behavioral patterns was Konrad Lorenz, the founder of modern ethology. He viewed licking as part of innate social rituals fixed in dogs due to their pack organization and close ties with relatives—wolves and jackals.

In wolf packs, puppies lick the muzzles of adults, stimulating them to regurgitate semi-digested food—a natural way to feed offspring. Over time, this gesture became a universal social signal: a display of submission, a request for attention, or confirmation of friendly intentions. That is why even adult dogs today use licking as a gentle way to show peacefulness and trust.

Modern dog behavior studies confirm that this phenomenon is highly multifunctional. Scientists note that licking is accompanied by the release of endorphins in the dog—hormones of pleasure and calm. Thus, this gesture often serves as an emotional regulator: the dog can relieve tension, seek support, or restore contact with the owner.

Additionally, during domestication, licking became part of interspecies “social glue”: the dog seems to “check” us using smell and taste receptors, gathering information about our emotional state, stress level, or even hormonal profile (yes, dogs can distinguish the scent of adrenaline and cortisol!). Recent studies show that when a dog licks an owner’s face or hands, the human’s oxytocin level—the attachment hormone—also rises, strengthening the bond between the two species.

So, from an ethological viewpoint, licking is not just affection or mischief. It is a complex, evolutionarily formed language combining ancestral social behavior, emotional self-regulation, and a powerful tool for interspecies communication. Most importantly, it is how a dog says: “You are mine, I trust you.”

Is Licking Dangerous for Humans: Hygienic and Medical Perspective

Licking is a natural gesture for a dog, but from a hygiene standpoint, it has nuances. In most cases, contact with saliva from a healthy, vaccinated, and regularly dewormed dog poses no significant threat to humans. However, it cannot be called completely safe—and here’s why.

A dog’s oral cavity hosts a large number of microorganisms: bacteria, fungi, and conditionally pathogenic flora. Most are harmless to humans, but some can cause skin or mucous membrane irritation, especially if the person has:

weakened immunity;
cracks or wounds on the skin;
chronic dermatological conditions.

Special attention should be paid to licking the face, mouth, and eye area. These mucous membranes are most sensitive and can easily become entry points for infections. Rare but possible cases include transmission of bacteria like Pasteurella or Capnocytophaga, or helminths if the dog is not dewormed.

Additionally:

if the dog eats raw meat, risks are slightly higher due to possible intestinal bacteria;
in children and elderly people, reactions may be stronger due to immature or weakened immunity.

However, it is important to emphasize: the risk is minimal if the dog is:

regularly vaccinated;
systematically treated for parasites;
has healthy teeth and gums;
eats quality food and has stable microflora.

Another View: Does Dog Licking “Immunize” Us?

Some scientists and popular media hypothesize that regular dog licking may provide humans with a form of immunization—not classical vaccination, but something like “immunizing subinfection.” The idea is that animal saliva microflora in small doses reaches the owner’s skin and mucous membranes, potentially stimulating the immune system and increasing microbial tolerance.

This concept draws from similar data showing positive effects of close animal contact on immune development—for example, a Japanese study found lower allergy risk in children raised with dogs or cats. However, direct studies proving that dog licking specifically builds human immunity are scarce. While appealing, in the scientific community it remains more hypothesis than fact.

Thus, while some owners may enjoy an “immune bonus” from dog licking, it does not replace standard hygiene—washing hands after saliva contact, especially with scratches or wounds, remains vital for safety and health.

Why Licking Sometimes Becomes Obsessive and What to Do

Although licking is a natural communication method, it can sometimes turn obsessive. Such “over-licking” may signal something amiss in the dog’s life. Most often, causes lie in emotional state or physical discomfort.

Main Causes of Obsessive Licking:

Stress and anxiety. Like humans, dogs can “self-soothe” with repetitive actions. Licking releases endorphins, so the animal subconsciously uses it to relieve tension. This often occurs after moves, loud noises, family changes, new pets, or prolonged solitude.
Boredom and lack of activity. If energy has no natural outlet—walks, play, training—the dog may switch to licking as an accessible action.
Behavioral pattern reinforced by attention. Owners sometimes unintentionally encourage it—smiling, petting, or talking when licked. The pet learns: “The more I lick, the more attention.”
Medical causes. Obsessive licking of hands or face may attempt to highlight personal discomfort: nausea, mouth pain, allergy, panic, or hormonal issues. Sudden onset warrants ruling out medical problems.

What Owners Should Do: Gentle, Evidence-Based Strategies

1. Add More Activity and Walks

Regular physical exercise is the simplest way to relieve psychological tension. Suitable options:

long walks;
search games;
scent trails;
obedience training;
trick work.

A tired (healthily) dog is a calm dog.

2. Redirect Attention to Alternative Behavior

When the dog starts obsessively licking, gently redirect to another action:

give a treat or calming cookie
offer a puzzle snack;
ask for a known command and reward.

This builds new neural links: instead of “lick → attention,” “perform → reward.”

3. Use Calming Supplements

Gentle, natural calming complexes help reduce anxiety, especially in emotionally sensitive dogs. Proven options include supplements based on:

CBD (cannabidiol)—regulates stress responses, improves sleep, reduces excessive excitability;
5-HTP—gently raises serotonin levels, promoting balance;

4. Avoid Accidentally Reinforcing Obsessive Behavior

Do not scold or raise your voice—it only increases anxiety. Instead:

calmly turn away;
remove your hands or stand up;
offer an alternative “correct” behavior.

Consistency is key to success.

5. Check Health

If obsessive licking appears suddenly or with other symptoms (restlessness, vomiting, itching, appetite changes), schedule a vet exam. Medical causes should be ruled out first.

Scientific Perspective

While the “immunization through licking” idea remains largely hypothetical, modern research reveals a profound biochemical kinship between dogs and humans. For instance, scientists found that positive social contacts—eye contact, petting, “gentle gestures”—raise oxytocin levels in both parties, the hormone of trust and attachment. This hormonal “chemical dialogue” truly explains why licking is often seen as unconditional love: when a dog licks us, it is not just a cute gesture but part of a deeper social language shaped by evolution.

So next time your four-legged friend licks you, it may be more than tenderness—a true “exchange of love”: physical, chemical, heartfelt. Let it remind us how special our bond with them is.