Do Dogs Cry Tears? The Science Behind Canine Emotional Responses
Do dogs cry tears like humans? Explore the science of canine tear production, emotional expression research, and what watery eyes really mean.
Every dog owner has had that moment: you come home after a long trip, your dog greets you with those big, glistening eyes, and you wonder — is my dog crying? The short answer involves some nuance that bridges veterinary ophthalmology, evolutionary biology, and canine cognition research.
Humans are the only animals confirmed to shed tears in response to emotions. Dogs, however, have a rich emotional life expressed through entirely different channels. Understanding what those watery eyes actually mean can help you distinguish between a touching reunion and a veterinary concern that needs attention.
The Science of Canine Tear Production
Dogs have a lacrimal system functionally similar to humans. The lacrimal glands, located above each eye, produce the aqueous (watery) layer of the tear film. Meibomian glands along the eyelid margins secrete the lipid layer that prevents evaporation. Goblet cells in the conjunctiva produce the mucin layer that helps tears adhere to the corneal surface.
This three-layer tear film — lipid, aqueous, and mucin — serves critical functions: lubricating the eyelid movement across the cornea, delivering oxygen and nutrients to the avascular corneal surface, flushing away debris, and providing antimicrobial protection through lysozyme and immunoglobulin A.
According to the Merck Veterinary Manual, basal tear production in dogs averages 15-25 mm per minute as measured by the Schirmer tear test (STT). Values below 15 mm/min suggest keratoconjunctivitis sicca (dry eye), while values above 25 mm/min indicate reflex tearing from irritation or obstruction.
Basal Tears vs. Reflex Tears vs. Emotional Tears
| Tear Type | Trigger | Function | Present in Dogs? |
|---|---|---|---|
| Basal | Continuous production | Corneal lubrication, nutrition, antimicrobial defense | Yes |
| Reflex | Irritants, foreign bodies, bright light, pain | Flush debris, dilute chemicals, protect cornea | Yes |
| Psychic (Emotional) | Sadness, grief, joy, emotional overwhelm | Stress hormone excretion, social signaling (in humans) | Unconfirmed — see research below |
The 2022 Tear Study: What Researchers Actually Found
In August 2022, a team led by Takefumi Kikusui at Azabu University in Japan published a study in Current Biology that generated significant media attention. The study examined 18 dogs and measured tear volume using the Schirmer tear test before and after reunions with their owners versus reunions with familiar non-owner humans.
The findings: dogs produced significantly more tears during reunions with their owners compared to baseline measurements and compared to reunions with familiar caretakers who were not their primary attachment figure. The researchers also found that applying oxytocin drops to dogs' eyes increased tear production, while an oxytocin receptor antagonist reduced it. This suggested the oxytocin-mediated bonding pathway — the same neurochemical system involved in human maternal-infant attachment — might drive the tear increase.
Important Caveats the Headlines Missed
Before concluding that dogs cry tears of joy, consider these methodological limitations:
- Sample size: Only 18 dogs participated, which is small for drawing species-wide conclusions.
- Tear measurement method: The Schirmer test measures total aqueous volume but does not differentiate tear composition. Human emotional tears contain higher concentrations of stress hormones (ACTH, leucine enkephalin) than reflex tears — this compositional analysis was not performed on the canine samples.
- Alternative explanations: Excitement increases heart rate, blood pressure, and autonomic nervous system activity in dogs. Increased parasympathetic activation during positive social interactions could stimulate lacrimal glands without the tears being "emotional" in the human sense.
- No negative emotion testing: The study only tested reunion scenarios (positive arousal). Dogs were not tested during separation distress, fear, or grief situations — the contexts where humans typically cry emotional tears.
The study demonstrates that dogs' tear production increases during emotionally significant reunions. Whether this constitutes "crying" depends on your definition. Veterinary behaviorists generally agree that this is more accurately described as oxytocin-mediated lacrimal response rather than emotional crying as humans experience it.
Evolutionary Basis: Why Wolves Don't Cry Tears
Evolutionary context: Domestic dogs (Canis lupus familiaris) diverged from gray wolves approximately 15,000-40,000 years ago. Wolf pups produce vocal distress signals and facial expressions to solicit care from pack members, but there is no documented evidence of wolves producing excess tears during emotional states.
The oxytocin feedback loop between dogs and humans — where mutual gaze increases oxytocin in both species — is a domestication adaptation not seen in wolves interacting with humans. The 2022 study's findings may reflect a domestication-driven enhancement of the oxytocin-lacrimal connection rather than an ancestral trait.
In wolves, visual signaling around the eyes serves different functions. The lighter facial markings around wolf eyes enhance gaze communication during coordinated hunting and social hierarchy maintenance. Dogs have retained and exaggerated some of these signals — breeds with more pronounced facial markings and larger-appearing eyes may have been inadvertently selected during domestication because they trigger human caregiving responses.
The tear production observed during dog-owner reunions might represent an evolutionary byproduct: as dogs evolved to bond with humans through oxytocin pathways, and oxytocin stimulates lacrimal glands, the visible tears became a secondary signal that humans interpret as emotional. This creates a feedback loop where humans respond to the tears with comfort, reinforcing the dog's attachment behavior.
How Dogs Actually Express Emotion (It's Not Through Tears)
Dogs have a sophisticated emotional communication system that does not rely on tears. Understanding these channels helps you read your dog's emotional state more accurately than watching for watery eyes.
Vocal Communication
Research published in Applied Animal Behaviour Science has documented distinct vocalization patterns for different emotional states in dogs:
- Separation distress: High-pitched whining, howling, and barking with shorter inter-bark intervals (typically 0.5-2 seconds apart). Puppies begin producing isolation calls as early as 2-3 weeks of age.
- Play solicitation: Lower-pitched, more variable "play barks" often paired with play bows (front end down, rear elevated).
- Fear/anxiety: High-pitched yelping, whimpering, or prolonged low growling with a closed mouth.
- Contentment: Soft sighing, low grumbling during petting, and rhythmic breathing patterns during rest.
Body Language and Facial Expression
The Dog FACS (Facial Action Coding System), developed by researchers at the University of Portsmouth, has identified 27 distinct facial action units in dogs. Key emotional indicators include:
| Emotional State | Facial Indicators | Body Indicators |
|---|---|---|
| Distress/Sadness | Inner eyebrow raise (AU101 — "puppy dog eyes"), ears pulled back, lip corners drawn back | Low tail carriage, tucked tail, lowered body posture, reduced activity |
| Joy/Excitement | Open mouth with relaxed lips, ears forward or neutral, bright eyes with normal aperture | Full-body wag, play bows, zoomies, relaxed muscle tone |
| Fear | Whale eye (sclera visible), ears flattened, lip licking, yawning | Cowering, trembling, tucked tail, attempts to hide or flee |
| Grief/Loss | Reduced facial animation, decreased responsiveness to stimuli, prolonged staring at specific locations | Appetite decrease, sleep pattern disruption, searching behavior, clinging to owner |
When Watery Eyes Signal a Medical Problem
Important: Persistent or excessive tearing (epiphora) is almost always a medical concern, not an emotional one. If your dog's eyes are consistently wet, stained, or producing discharge, consult your veterinarian. Early treatment of eye conditions prevents corneal damage and vision loss.
Common Causes of Excessive Tearing in Dogs
Brachycephalic breeds (French Bulldogs, Pugs, Shih Tzus, Boston Terriers) are especially prone to epiphora due to their shallow orbits and shortened facial structure. The medial canthus (inner eye corner) often has insufficient space for proper tear drainage through the nasolacrimal duct.
Specific conditions include:
- Nasolacrimal duct obstruction: The tear drainage pathway from the eye to the nose becomes blocked. Congenital in some breeds (Poodles, Cocker Spaniels), acquired through inflammation or dental disease. Diagnosis involves nasolacrimal flush under sedation ($200-$500 at most general practices).
- Entropion: Eyelid rolls inward, causing eyelashes to rub against the cornea. Common in Shar-Peis, Chow Chows, Bulldogs. Requires surgical correction ($500-$1,500 per eye).
- Distichiasis: Abnormal eyelashes grow from the meibomian gland openings and irritate the cornea. Seen in Shih Tzus, Lhasa Apsos, Dachshunds. Treatment ranges from manual epilation to cryosurgery ($300-$800).
- Keratoconjunctivitis sicca (KCS/dry eye): Paradoxically, early KCS can cause reflex tearing before the condition progresses to obvious dryness. Immune-mediated destruction of lacrimal glands is the most common cause. Lifelong cyclosporine or tacrolimus treatment costs $15-$40/month.
- Corneal ulcers: Painful scratches or erosions on the corneal surface trigger profuse reflex tearing. Fluorescein staining confirms diagnosis. Treatment costs $100-$300 depending on severity.
- Allergic conjunctivitis: Environmental allergens (pollen, dust mites, mold) cause bilateral redness and tearing. Often seasonal. Antihistamine eye drops or systemic oclacitinib (Apoquel) at $1.50-$3.00/day depending on dog weight.
- Glaucoma: Increased intraocular pressure causes pain, tearing, and eventual blindness if untreated. IOP above 25 mmHg is abnormal (normal canine range: 10-25 mmHg). Emergency treatment with dorzolamide/timolol drops ($20-$40/bottle) or surgical intervention ($1,000-$2,500).
Tear Staining: What Those Rusty Marks Mean
The reddish-brown staining on light-colored fur below the inner eye corner is caused by porphyrins — iron-containing molecules excreted in tears, saliva, and urine. When tears remain on the fur and are exposed to air, porphyrins oxidize and create the characteristic rust color.
This is cosmetic in mild cases but indicates chronic tear overflow. Breeds most affected include Maltese, Bichon Frises, Poodles, and Shih Tzus. Daily wiping with a damp cloth and products containing boric acid or mild hydrogen peroxide solutions (like Angels' Eyes or Eye Envy, typically $12-$25 for a 4 oz bottle) can manage staining, but addressing the underlying cause of excess tearing is more important.
Myths vs. Facts About Dogs and Crying
| Common Myth | Scientific Reality |
|---|---|
| "My dog cries tears when I leave for work because they're sad." | Separation anxiety in dogs manifests as vocalization, destructive behavior, pacing, drooling, and inappropriate elimination — not tear production. Wet eyes during departures are coincidental or related to environmental irritants. |
| "Dogs cry at the vet because they know something bad is about to happen." | Tearing at the vet is reflex tearing from stress-induced autonomic arousal, bright examination lights, or physical restraint pressure around the head/neck. Dogs do react to veterinary environments, but the tears are physiological, not emotional. |
| "If a dog howls, it's crying." | Howling is a distance-increasing vocalization inherited from wolves. It serves location communication, social bonding, and response to high-pitched sounds. It is not equivalent to human crying and does not necessarily indicate distress. |
| "My dog shed a tear when their companion died — they were grieving." | Dogs do experience grief-like behavioral changes after losing a companion (decreased appetite, lethargy, searching behavior). However, documented tear production during grief has not been scientifically confirmed in dogs. The observed moisture was more likely reflex tearing or coincidental basal tear overflow. |
| "Dogs don't feel emotions deeply enough to cry." | MRI studies by Gregory Berns at Emory University demonstrated that dogs have emotional processing in the caudate nucleus similar to humans. Dogs experience joy, fear, attachment, and likely grief. The absence of emotional tears reflects a different communication system, not an absence of feeling. |
Breed Variations in Tear Production and Eye Anatomy
Not all dogs are equally likely to show visible tearing. Breed-specific anatomy plays a major role in how much tear overflow you'll observe.
High-Epiphora Breeds
Brachycephalic breeds consistently show the highest rates of tear overflow due to their compressed facial structure:
- Pugs: Shallow orbits cause prominent globes (exophthalmos) with incomplete blink coverage. Tear film evaporates faster, triggering reflex tearing. Median STT values: 22-30 mm/min (above normal range).
- French Bulldogs: Medial entropion and lower punctal aplasia (missing tear drainage openings) are common. Estimated 15-20% of Frenchies have congenital punctal abnormalities.
- Shih Tzus: Long facial hair wicks tears onto the face. Combined with mild medial entropion and prominent medial canthal folds, chronic epiphora affects an estimated 40-60% of the breed.
- Pekingese: Extreme brachycephaly with nasal fold trichiasis (nose fold hair rubbing on cornea) causes constant irritation and tearing.
Breeds with Minimal Visible Tearing
Dolichocephalic breeds (long-nosed) and mesocephalic breeds with proper eyelid conformation typically have efficient tear drainage:
- Greyhounds, Whippets, Salukis: Tight eyelid conformation and deep-set eyes result in efficient tear drainage with minimal overflow.
- German Shepherds, Belgian Malinois: Normal orbital anatomy with efficient nasolacrimal drainage. Visible tearing usually indicates genuine medical concern in these breeds.
- Labrador Retrievers, Golden Retrievers: Generally good eye conformation, though older Labs can develop acquired nasolacrimal issues.
What This Means for Dog Owners: Practical Guidance
Understanding the science behind canine tear production changes how you respond to your dog's watery eyes. Here's a decision framework for real situations:
When to Monitor vs. When to See the Vet
| Scenario | Likely Cause | Action |
|---|---|---|
| Brief tearing during excited greeting, stops within 2-5 minutes | Autonomic arousal / oxytocin response | No action needed — normal physiological response |
| One eye tearing persistently, other eye normal | Foreign body, corneal scratch, localized infection, or unilateral duct obstruction | Vet visit within 24-48 hours; sooner if dog is squinting or pawing at eye |
| Both eyes tearing with yellow/green discharge | Bacterial or viral conjunctivitis | Vet visit within 24 hours — prescription antibiotic drops likely needed ($30-$60) |
| Tearing with squinting, redness, and apparent pain | Corneal ulcer, glaucoma, or uveitis | Emergency vet visit — corneal ulcers can perforate within 24-48 hours if untreated |
| Chronic tear staining on a brachycephalic breed, no discomfort | Anatomical epiphora | Daily cleaning + discuss nasolacrimal evaluation at next wellness exam |
| Tearing started after new food, environmental change, or seasonal shift | Allergic conjunctivitis | Monitor 3-5 days; if persistent, vet visit for allergy assessment |
Daily Eye Care for Tear-Prone Breeds
If you own a brachycephalic breed or a dog with chronic epiphora, a consistent eye care routine prevents secondary skin infections (moist dermatitis) and keeps your dog comfortable:
- Wipe twice daily with a sterile, pre-moistened eye wipe (Optixcare Eye Cleaning Wipes or Eye Envy pads, $8-$15 for a 90-count pack). Use a separate wipe for each eye to prevent cross-contamination.
- Trim periocular hair every 2-3 weeks. Use blunt-tipped grooming scissors (like the Gimars Professional Rounded Safety Scissors, ~$8) to carefully trim hair that contacts the corneal surface. Never use pointed scissors near your dog's eyes.
- Apply a barrier product if staining is severe. A thin layer of petroleum jelly or a commercial product like Eye Envy Tear Stain Barrier ($14-$18) applied below the inner eye corner prevents tears from soaking into the fur.
- Flush monthly with a sterile saline eyewash (available at pharmacies for ~$5-$8) to clear debris from the tear duct openings. Gently direct the stream from the outer to the inner eye corner.
Frequently Asked Questions
Why do dogs have watery eyes if they don't cry emotional tears?
Watery eyes in dogs are caused by basal tear production (continuous lubrication), reflex tearing (response to irritants, pain, or bright light), or anatomical issues that prevent proper tear drainage. The brief increase in tears some dogs show during owner reunions may be related to oxytocin-driven lacrimal stimulation, but this is physiologically different from human emotional crying.
Can dogs feel sad without crying?
Yes. Dogs experience sadness, grief, and distress — neuroimaging and behavioral studies confirm this. They simply express these emotions through body language (lowered posture, reduced tail wagging, decreased appetite), vocalization (whining, howling), and behavioral changes (withdrawal, clinginess, sleep disruption) rather than through tears.
How do dogs process emotions differently from humans?
Dogs process emotions primarily through the limbic system, similar to humans, but their emotional communication evolved around olfactory signals, body postures, and vocalizations rather than facial expressions involving tears. The canine amygdala is proportionally larger relative to brain size than in humans, suggesting strong emotional processing capacity. However, dogs lack the prefrontal cortex complexity that enables humans to have meta-emotional awareness (thinking about their feelings).
What does it mean when my dog whimpers and has wet eyes?
Combined whimpering and tearing most likely indicates physical discomfort rather than emotional sadness. Common causes include eye irritation (foreign body, corneal scratch), ear infection, dental pain, or gastrointestinal upset. If this combination persists for more than a few hours or is accompanied by behavioral changes, consult your veterinarian for a physical examination.
Is it normal for my dog to tear up when eating?
Some dogs experience gustatory lacrimation — tear production stimulated by eating. This can be normal in brachycephalic breeds due to the close anatomical relationship between the oral cavity and nasolacrimal system. However, if tearing during meals is new or worsening, it could indicate a dental problem (tooth root abscess near the nasolacrimal duct) or an oronasal fistula. A veterinary dental exam is warranted for new-onset eating-related tearing.
How is canine tear production different from humans?
Humans are the only confirmed species that produces psychic (emotional) tears containing stress-specific biochemical markers. Human emotional tears contain elevated levels of adrenocorticotropic hormone (ACTH), leucine enkephalin, prolactin, and potassium compared to reflex tears. Canine tear composition has not been shown to vary based on emotional state, though the 2022 oxytocin study suggests the mechanism for emotion-linked tear variation may exist in dogs — it simply hasn't been studied at the biochemical level yet.
Key sources referenced in this article:
- Nagasawa, M., Mitsui, S., En, S., et al. (2022). "Dogs' tears increase in volume during reunions with their owners." Current Biology, 32(16).
- Merck Veterinary Manual — Eye and Orbit: Structure and function of the canine lacrimal system.
- Berns, G. (2013). How Dogs Love Us. Emory University fMRI research on canine emotional processing.
- Kaminski, J., Waller, B.M., Diemoitz, R., et al. (2019). "Evolution of facial muscle anatomy in dogs." PNAS, 116(29).
Dr. Hannah Wickes
All our authors care for dogs every day — read more of their work on the authors page.
