My Dog Bear Its Teeth? Canine Facial Signals
Why does my dog bear its teeth? Explore the canine science behind teeth-baring, submissive grins, and aggression signals with expert behavioral insights.
Search “dog bear teeth” online and you’ll find a tangle of conflicting advice. Some sources say it’s always aggression. Others insist certain breeds are just “smiling.” The reality, as decades of canine behavioral research demonstrate, is far more nuanced — and understanding the science behind why dogs expose their teeth can fundamentally change how you read your dog’s emotional state.
The Two Faces of Teeth-Baring: Snarl vs. Submissive Grin
Before we dig into the evolutionary and neurological mechanisms, you need a reliable framework for telling these two behaviors apart. Veterinary behaviorists distinguish them through a constellation of signals, never a single feature in isolation.
| Feature | Aggressive Snarl | Submissive Grin |
|---|---|---|
| Lip position | Upper lip lifted vertically, exposing canines and incisors; muzzle wrinkled | Lips pulled horizontally backward (commissures retracted), exposing mostly front incisors |
| Muzzle tension | Pronounced wrinkles (rugae) on the bridge of the nose | Smooth muzzle, no wrinkling |
| Eye expression | Hard, direct stare; visible sclera (“whale eye”); fixed pupils | Soft, squinty eyes; averted gaze; relaxed brow |
| Ear position | Pinned forward (alert breeds) or flat against head (fear-based aggression) | Pulled back and relaxed, often with head lowered |
| Body posture | Stiff, leaning forward; weight on front legs; tail high and rigid or stiff-wagging | Lowered body; weight shifted back; tail low or tucked; may crouch or roll |
| Vocalization | Low-pitched growl (often 100–400 Hz); may escalate to bark | Usually silent, or soft whine/high-pitched vocalization |
| Context triggers | Resource guarding, territorial intrusion, pain, fear, redirected frustration | Greeting a higher-status individual, being scolded, meeting unfamiliar dogs/people |
The critical insight from ASPCA behavioral resources is that context determines meaning. A Dalmatian grinning when you walk through the door after work is performing an appeasement greeting — not threatening you. A German Shepherd snarling over a bone is issuing a clear warning. Confusing the two can lead to punishment of a friendly behavior or, worse, ignoring a genuine bite-risk signal.
The Evolutionary Origin: Why Ancestral Canids Exposed Their Teeth
Research published in the Journal of Veterinary Behavior has demonstrated that domestic dogs retain the full repertoire of ancestral agonistic (conflict-related) and affiliative (bonding-related) facial displays, but with one significant modification: dogs direct these signals toward humans far more frequently than wolves do. This is partly a product of domestication selecting for neoteny — the retention of juvenile traits into adulthood. Adult dogs, like wolf pups, remain socially oriented toward caregivers and continue using appeasement signals well past the age at which wolves would stop.
The Merck Veterinary Manual notes that the submissive grin in dogs is functionally analogous to the “submissive grin” observed in wolf pups greeting adult pack members. In wolves, this behavior typically fades as pups mature and establish rank. In dogs, it often persists lifelong — particularly in breeds selected for strong human-directed social engagement, such as Golden Retrievers, Dalmatians, and many spaniel breeds.
The Neurological Mechanism: How the Brain Produces a Snarl or Grin
Teeth-baring is controlled by the interplay of several neurological systems:
- The amygdala processes threat assessment. When a dog perceives a potential threat (a stranger approaching its food bowl, an unfamiliar dog entering its space), the amygdala activates the hypothalamus and brainstem nuclei that control facial musculature.
- The trigeminal nerve (Cranial Nerve V) innervates the muscles of mastication and facial expression, including the levator labii superioris alaeque nasi — the muscle responsible for lifting the upper lip in a snarl.
- The sympathetic nervous system triggers the fight-or-flight cascade: cortisol and adrenaline surge, pupils dilate, and the dog’s body stiffens. A snarl during this state is a component of a full autonomic arousal response.
- The parasympathetic system, in contrast, governs the relaxed state during a submissive grin. The dog’s heart rate may actually decrease slightly; the facial muscles contract in a different pattern (commissure retraction rather than lip elevation).
Importantly, the two types of teeth-baring recruit different muscle groups. A snarl primarily uses the levator labii muscles to raise the upper lip vertically — the same muscles involved in a human sneer. A submissive grin uses the zygomaticus and risorius muscles to pull the lip corners horizontally backward. This anatomical distinction is why veterinary behaviorists can reliably differentiate the two displays on slow-motion video analysis, even when they appear superficially similar to an untrained observer.
Serotonin levels also modulate these displays. Dogs with lower cerebrospinal fluid concentrations of 5-HIAA (a serotonin metabolite) tend to display impulsive aggression with shorter warning latency — meaning they may snarl and bite with less escalation time. This is one reason selective serotonin reuptake inhibitors (SSRIs) like fluoxetine are sometimes prescribed by veterinary behaviorists for dogs with impulse-control aggression.
Breed Variations: Which Dogs Grin, Snarl, or Do Something Unusual?
Not all dogs display teeth-baring equally. Brachycephalic (short-muzzled) breeds like Pugs, Bulldogs, and Shih Tzus have compressed facial musculature that can make their expressions harder to read. A Pug’s “snarl” may look more like a grimace due to its shortened maxilla, and its natural wrinkled muzzle can mask the rugae that signal genuine aggression in longer-muzzled breeds.
Conversely, some breeds are notorious for pronounced submissive grins:
- Dalmatians — widely documented for their “Dalmatian smile,” a full submissive grin displayed during greetings
- Golden Retrievers — often grin when greeting owners or meeting new people
- Samoyeds — their famous “Sammy smile” is partly structural (upturned mouth corners) and partly a submissive greeting display
- Cocker Spaniels — frequently display submissive grins combined with excited urination during greetings
Breeds originally selected for guarding or protection work (Rottweilers, Doberman Pinschers, Caucasian Shepherd Dogs) tend to have more pronounced and clearly differentiated snarl displays. This isn’t because they are inherently more aggressive — it’s because selective breeding for protective behavior maintained strong, unambiguous threat signaling. A Rottweiler’s snarl is typically textbook: vertical lip lift, full canine exposure, deep growl, rigid forward posture. There is little ambiguity, which is actually a safety advantage for owners who know how to read it.
What It Means When Your Dog Bears Its Teeth: Practical Implications for Daily Life
- Never punish a submissive grin. If your dog grins when you approach after it has chewed something it shouldn’t, it is already communicating deference and stress. Punishment (yelling, physical correction) will increase anxiety and may convert an appeasement display into a fear-based defensive bite over time. Instead, manage the environment: use baby gates, crate training, and positive reinforcement to prevent unwanted chewing.
- Respect a snarl as information, not defiance. A snarling dog is telling you it feels threatened, in pain, or pushed past its comfort threshold. The correct response is to remove the trigger (back away, remove the contested resource, stop the interaction), not to “dominate” the dog. Consult a certified professional dog trainer (CPDT-KA or IAABC-certified) or a veterinary behaviorist (DACVB) for a structured behavior modification plan.
- Teach children the difference. Children are disproportionately likely to be bitten because they misread a snarl as a “smile.” Teach kids: if a dog’s nose is wrinkled and the dog is growling, freeze, avoid eye contact, and slowly back away. Never approach a dog that is showing teeth.
- Watch for context shifts. A dog that grins submissively in greeting but snarls when approached while eating has two separate behavioral profiles. Resource guarding requires specific counter-conditioning protocols (trading up for higher-value items, desensitization to approach during meals) — not general obedience training.
If your dog’s teeth-baring is new, escalating in frequency, or occurring in contexts where it previously did not, schedule a veterinary exam before assuming it’s purely behavioral. Pain-related aggression accounts for a significant percentage of new-onset aggression cases in dogs over age 5. Conditions like osteoarthritis, dental disease, intervertebral disc disease (IVDD), and hypothyroidism can all lower a dog’s aggression threshold. Your veterinarian will typically run a complete blood count (CBC), serum chemistry panel, and thyroid panel (cost range: $150–$350 at most general practices) to rule out medical causes before referring to a behaviorist.
Common Misconceptions Debunked
| Myth | Fact |
|---|---|
| “My dog is smiling at me because it’s happy.” | A true canine “smile” (submissive grin) signals appeasement and social deference, not necessarily joy. A happy, relaxed dog more commonly displays an open mouth with a relaxed tongue loll, not teeth exposure. |
| “If a dog shows teeth, it will definitely bite.” | A snarl is a warning — it means the dog is communicating a desire to avoid biting. Most dogs progress through an escalation ladder (freeze → stare → growl → snarl → snap → bite). Punishing the snarl removes the warning step and can produce a dog that bites without signaling first. |
| “Some breeds are just ‘smiley’ and it doesn’t mean anything.” | Even in breeds prone to submissive grins, the behavior carries communicative meaning. It signals social stress or deference. Ignoring it means missing your dog’s attempt to tell you it feels uncertain. |
| “Dogs bare teeth to show dominance.” | The dominance framework has been largely discredited in modern canine behavioral science (see AVSAB position statement). Teeth-baring reflects emotional state (fear, frustration, pain, or appeasement), not a calculated attempt to climb a social hierarchy. |
When Teeth-Baring Signals a Problem: Medical and Behavioral Red Flags
🚨 Consult Your Veterinarian If:
- Your dog suddenly begins snarling or growling with no prior history of aggression
- Teeth-baring is accompanied by lethargy, appetite changes, or reluctance to be touched in specific areas
- Your dog snarls when picked up, when lying down, or when moving — possible indicators of musculoskeletal pain
- A previously submissive-grinning dog begins snarling in the same contexts (possible escalation from anxiety to fear-aggression)
- Teeth-baring is paired with disorientation, head-pressing, or seizures — these suggest neurological disease and require emergency evaluation
For behavioral concerns that are not medically driven, seek a board-certified veterinary behaviorist (DACVB) or an IAABC-certified dog behavior consultant. Expect initial consultation fees of $200–$500 and a multi-session behavior modification plan spanning 8–16 weeks.
How Is This Different From Humans?
Humans bare teeth primarily in a smile — a signal of positive affect, greeting, or social bonding. Our closest primate relatives, chimpanzees, use a “fear grin” (teeth bared, lips retracted) that is functionally closer to a dog’s submissive grin than to a human smile. This is a case of convergent signaling: across mammalian species, exposing vulnerable anatomy (teeth, throat, belly) communicates non-threatening intent.
The key difference is that humans have largely lost the aggressive snarl as a functional threat display. When we see a dog baring teeth, our cultural instinct is to map it onto a human smile — which is precisely why misinterpretation is so common and so dangerous. Dogs did not evolve to “smile” the way we do. They evolved to communicate threat gradients and social appeasement through facial musculature that happens to involve the same anatomical structures we associate with happiness.
Is it normal for my dog to bear its teeth when excited?
Some dogs display a brief, involuntary teeth exposure during high-arousal greetings — sometimes called a “submissive sneeze-grin” combination. If the body is loose, the tail is wagging in wide arcs, and the dog immediately transitions to relaxed play behavior, this is generally a normal variant of excited greeting behavior. If the body is stiff or the display persists, consult a behavior professional.
Can dogs actually smile on purpose?
Dogs can learn to offer a “smile” (teeth exposure) as a trained operant behavior if it is consistently reinforced. However, this is a shaped trick, not a spontaneous emotional expression. The dog has learned “when I pull my lips back, I get a treat” — it has not adopted smiling as an emotional communication in the human sense.
Why does my dog bare its teeth when I hug it?
Many dogs find hugging (encircling pressure around the neck/torso) inherently stressful. A snarl during a hug is a clear request to stop. A grin may indicate appeasement under stress. Either way, the dog is communicating discomfort. Respect the signal and find other ways to show affection that your dog finds genuinely pleasant — such as chest scratches or calm proximity.
What should I do if my dog bares teeth at another dog at the park?
Calmly increase distance. Do not punish, yell, or physically force your dog into closer proximity. A snarl at the dog park is your dog telling you it needs more space. If this happens repeatedly with multiple dogs, your dog may benefit from structured parallel-walk introductions and counter-conditioning rather than unstructured dog-park socialization.
Do puppies bare their teeth, and does it mean the same thing?
Puppies frequently mouth and show teeth during play — this is normal exploratory and social behavior, not aggression. However, puppies can also display genuine fear-based snarling if they are in pain, cornered, or poorly socialized. If a puppy under 16 weeks consistently snarls with stiff body language during handling, consult your veterinarian and a positive-reinforcement trainer early — intervention during the critical socialization window (3–14 weeks) has the best prognosis.
- AVSAB Position Statement on Dominance — avsab.org
- Merck Veterinary Manual: Normal Behavior in Dogs — merckvetmanual.com
- ASPCA: Common Dog Behavior Issues — aspca.org
Aaron Whyte
All our authors care for dogs every day — read more of their work on the authors page.
