Dogs wrinkle their nose for several distinct reasons, from warning you to back off to processing an interesting scent more deeply. The specific meaning depends heavily on what the rest of the dog’s body is doing at the same time. A wrinkled nose paired with a stiff body and pinned ears sends a very different message than one paired with squinty eyes and a wagging tail.
The Muscles Behind the Wrinkle
Dogs have a facial muscle that lifts the upper lip and pulls it to the side while also flaring the nostrils open. When this muscle contracts, the skin on top of the muzzle bunches upward, creating those distinctive horizontal wrinkles. This single movement serves double duty: it can expose the teeth as a visual warning, and it can physically widen the nostrils to pull in more air and scent molecules. The context determines which purpose the dog is using it for.
Aggression and Warning Signals
The most common reason people notice nose wrinkling is during an aggressive display. When a dog feels threatened, the wrinkled nose is part of a coordinated warning package: curled lips revealing the front teeth, a closed or tight mouth, low rumbling growls, ears pinned flat against the head, and a rigid body. The hair along the upper back (the hackles) often stands up at the same time. Every part of this display is designed to say “back off” without the dog having to escalate to a bite.
This is different from what you’ll see during rough play between two dogs. Play snarls tend to be exaggerated and theatrical, with big open-mouthed grins, loose wiggly bodies, and growling that sounds almost cartoonishly over the top. A dog who is genuinely upset will be stiff, tight-lipped, and quiet in comparison. If you’re trying to figure out whether two dogs are playing or fighting, stiffness is the single most reliable indicator of trouble.
The Submissive Grin
Some dogs wrinkle their nose in a way that looks alarming but actually means the opposite of aggression. This is called a submissive grin, and it’s one of the most commonly misread expressions in dogs. The dog pulls its lips back to show its front teeth, wrinkling the nose in the process, but the rest of its body tells an entirely different story: squinted or soft eyes, a low and loosely wagging tail, a body curved into a C shape, and sometimes a fully exposed belly.
Dogs typically direct this expression at people or other dogs they’re greeting with deference. It’s essentially a canine way of saying “I’m not a threat.” If you’ve ever come home to a dog who seems to be snarling at you while simultaneously wiggling its entire back end, you’ve seen a submissive grin in action. The key distinction is always in the body. A stiff dog showing teeth is warning you. A wiggly dog showing teeth is being polite.
Processing Scent More Intensely
Not every nose wrinkle is about communication. Dogs sometimes curl their lips and flare their nostrils to activate a secondary scent-processing system called the vomeronasal organ (or Jacobson’s organ). This structure sits inside the nasal cavity and opens into the roof of the mouth behind the upper front teeth. It’s specifically wired to detect pheromones and other chemical signals from other animals.
When a dog curls its lips and flares its nostrils, it physically opens up this organ, increasing the nasal cavity’s exposure to scent molecules. You’re most likely to see this when a dog encounters urine markings from other dogs, the scent of a female in heat, or any novel biological smell that carries social information. The brain region connected to this organ deals primarily with mating and social identification, so the dog is essentially running a chemical background check. This behavior looks less like a snarl and more like a brief, focused lip curl, often with a slightly glazed or distracted expression.
Discomfort or Irritation
Dogs also wrinkle their nose in response to physical irritation. A strong chemical smell, dust, pollen, or something tickling the muzzle can trigger a quick nose scrunch, sometimes followed by a sneeze. This is reflexive rather than communicative. You’ll notice it’s fleeting, lasting only a second or two, and the dog typically shakes its head or sneezes immediately afterward. If your dog is wrinkling its nose repeatedly without an obvious trigger, or pawing at its face, that can point to allergies, a nasal irritant, or dental pain that’s worth investigating.
Breed Differences in Nose Wrinkling
Some breeds look like they’re permanently wrinkling their noses simply because of how their skulls are shaped. Flat-faced (brachycephalic) breeds like French Bulldogs, Pugs, English Bulldogs, Pekingese, Boston Terriers, and Shar Peis have shortened skulls that cause excessive skin to fold around the muzzle, eyes, and ears. These folds aren’t expressions. They’re structural, present whether the dog is happy, angry, or asleep.
Those permanent skin folds do create a real health concern. Skin fold dermatitis is a major problem in these breeds, particularly in Bulldogs and Pugs. Moisture and debris get trapped between the folds, creating a warm, dark environment where bacteria and yeast thrive. Signs include redness, hair loss, crusting, a foul smell, and visible irritation in the creases of the face. In severe cases, the skin can become ulcerated. Keeping facial folds clean and dry is a routine part of caring for these breeds, and persistent redness or odor signals an infection that needs treatment.
Reading the Whole Dog
The nose wrinkle itself is ambiguous. It can mean aggression, submission, intense scent processing, or simple irritation. What makes the meaning clear is everything happening around it. A quick checklist of what to look at alongside the wrinkled nose:
- Body tension: Stiff and rigid suggests a genuine warning. Loose and wiggly suggests play or a submissive grin.
- Mouth shape: A closed, tight mouth with visible teeth is a threat. A wide-open mouth with a relaxed jaw is playful or friendly.
- Ear position: Pinned flat and back usually accompanies fear or aggression. Relaxed or forward-facing ears are neutral or curious.
- Tail position: A high, stiff tail or a tucked tail paired with nose wrinkling signals stress. A low, loose wag signals friendliness.
- Duration: A sustained wrinkle during a social interaction is communicative. A brief scrunch followed by a sneeze is physical.
Dogs are remarkably consistent in how they combine these signals. Once you start reading the full body instead of focusing on the nose alone, misinterpreting the expression becomes much harder.