Why Do Some Dogs Have Jowls? The Science Behind Saggy Cheeks
Why do some dogs have jowls? Explore the evolutionary, anatomical, and breed-specific science behind canine jowls, plus care tips and health red flags.
The Quick Answer: Why Do Dogs Have Jowls?
Not all dogs have prominent jowls, and the variation is not random. It is the product of thousands of years of human-directed selection layered on top of ancestral canine anatomy. Understanding why your dog has jowls — and what those jowls mean for their daily health — requires a look at evolutionary biology, breed history, and modern veterinary dermatology.
The Evolutionary Basis: From Wolves to Wrinkled Companions
In the wild, canids benefit from streamlined facial anatomy. Excess skin around the muzzle would be a liability: it could snag on brush, collect debris, and impair thermoregulation. So why did jowls emerge in domestic dogs at all?
The answer lies in functional selection for working breeds. Early humans bred dogs for specialized tasks, and in several lineages, loose facial skin conferred advantages:
- Scent hounds (Bloodhounds, Basset Hounds, Coonhounds): Long, drooping jowls and dewlaps create a micro-environment around the nose and mouth that traps volatile scent compounds. As the dog moves with its nose to the ground, air currents carry odor molecules upward into the folds, effectively concentrating the scent. Research published in the Applied Animal Behaviour Science journal has noted that brachycephalic and mesocephalic scent breeds demonstrate superior olfactory tracking partly due to facial morphology directing airflow.
- Mastiff-type guardian breeds (English Mastiff, Neapolitan Mastiff, Cane Corso): Loose, thick facial skin served as armor. When these dogs confronted predators or intruders, an attacker would grab folds of skin rather than reaching muscle, blood vessels, or bone. The jowls acted as a crumple zone — sacrificial tissue that could sustain damage without incapacitating the dog.
- Water retrieval breeds (Newfoundland, Saint Bernard): Some researchers propose that loose facial tissue, combined with large flews (upper lips), helped channel water away from the airway during swimming and water rescue work, though this hypothesis is less well-documented in peer-reviewed literature.
Importantly, a secondary mechanism amplified jowl development across many breeds: domestication syndrome. The neural crest cell hypothesis, proposed by geneticist Adam Wilkins and colleagues, suggests that selecting for tameness inadvertently altered neural crest cell migration during embryonic development. This produced a suite of correlated physical changes — floppy ears, shorter muzzles, reduced tooth size, and looser skin — that we see across many domesticated species. Jowls in dogs may partly be a byproduct of this broader developmental shift.
The Physiological Mechanism: What Are Jowls Made Of?
To understand why jowls behave the way they do — why they sag, drool, and sometimes become infected — you need to understand their composition:
| Tissue Layer | Composition | Function |
|---|---|---|
| Epidermis | Keratinized epithelial cells, melanocytes | Barrier protection, pigmentation |
| Dermis | Collagen fibers (Type I and III), elastin, glycosaminoglycans | Structural support, elasticity, hydration |
| Subcutaneous tissue | Adipose (fat) deposits, loose connective tissue | Cushioning, insulation, energy storage |
| Cutaneous muscles | Platysma, cutaneous faciei muscles | Facial expression, skin tension control |
| Mucosal lining (inner) | Non-keratinized stratified squamous epithelium, salivary gland ducts | Moisture regulation, saliva transport |
The key structural component is the dermal collagen-elastin matrix. In breeds with pronounced jowls, this matrix is both more abundant and organized differently than in tight-faced breeds. The elastin fibers, which normally snap skin back into position, are either less dense or arranged in a way that permits greater gravitational sag.
Saliva production is closely tied to jowl anatomy. The parotid, mandibular, sublingual, and zygomatic salivary glands continuously produce saliva, and in jowled breeds, the deep folds of the flews and lower lip create channels where saliva pools rather than being swallowed. This is why breeds like the Saint Bernard and Mastiff are prolific droolers — it is not that they produce more saliva than a Greyhound (though some individuals do), but that their facial anatomy fails to contain it.
Breed Variations: Which Dogs Have the Most (and Least) Pronounced Jowls?
Jowl development falls on a spectrum. The American Kennel Club breed standards explicitly describe facial fold characteristics for many breeds, which gives us a useful framework for comparison.
| Breed | Jowl Severity | AKC Standard Language | Functional Origin |
|---|---|---|---|
| Bloodhound | Extreme | "Skin is loose and pendulous, falling in deep folds" | Scent tracking — traps odor particles |
| English Mastiff | Extreme | "Muzzle is broad, deep, and somewhat flattened; flews moderately pendulous" | Guardian/combat protection |
| Neapolitan Mastiff | Extreme | "Heavy wrinkles and folds on the head; pronounced dewlap" | Estate guardian — protective armor |
| Saint Bernard | Moderate to Extreme | "Flews of upper jaw are strongly developed, pendulous" | Alpine rescue, cold-weather insulation |
| Basset Hound | Moderate to Extreme | "Lips are dark in color, well-flewed; dewlap pronounced" | Scent trailing at ground level |
| Bulldog | Moderate | "Chops (flews) are thick, broad, pendant, and very deep" | Bull-baiting (historical) — gripping protection |
| Boxer | Mild | "Flews are thick and padded; not overly pendulous" | Working/guard — moderate protection |
| Labrador Retriever | Minimal | "Lips should not be too square or jowly" | Retrieval — clean mouth for carrying game |
| Greyhound | Absent | "Lips tight, well-pigmented" | Cursorial hunting — aerodynamic efficiency |
Notice the pattern: breeds developed for close-contact physical work (guarding, holding, fighting) or ground-level scent work tend to have the most pronounced jowls, while breeds built for speed or precision retrieval have tight, minimal facial skin.
Practical Implications: What Jowls Mean for Daily Care
If your dog has prominent jowls, here is what you need to know about day-to-day management:
Drool Management
Jowled breeds drool — sometimes in staggering quantities. A mature English Mastiff can produce 1 to 2 cups of saliva per day that ends up outside the mouth. Practical strategies:
- Keep a designated "drool rag" (microfiber cloths work best, roughly $8–$12 for a 6-pack) accessible in every room
- Use a snood or bib during meals and water breaks to catch excess moisture
- Wipe the jowls and chin after every meal and drink session to prevent skin maceration
- Place washable mats under water bowls — expect a 2–3 foot splash/drool radius
Fold Hygiene and Infection Prevention
The warm, moist environment inside jowl folds is an ideal breeding ground for bacteria (especially Staphylococcus pseudintermedius) and yeast (Malassezia pachydermatis). According to the Merck Veterinary Manual, skin fold dermatitis (intertrigo) is one of the most common dermatological conditions in brachycephalic and heavily wrinkled breeds.
Daily fold care protocol:
- Gently lift each jowl fold and inspect for redness, odor, or discharge
- Wipe inside the fold with a veterinary-grade chlorhexidine wipe (e.g., Chlorhexidine 2% wipes, approximately $12–$18 for a 50-count box) or a soft cloth dampened with diluted chlorhexidine solution
- Dry the fold thoroughly — moisture left behind accelerates microbial growth
- Apply a thin barrier ointment (petroleum-free, zinc oxide-free formula like Vetricyn Plus Wound Care, ~$15) if folds are prone to chafing
Expected annual veterinary cost for fold-related dermatitis treatment: $150–$600 depending on severity and frequency, including cytology exams ($45–$80 per visit), topical antimicrobials, and oral antibiotics for secondary infections.
Dental Health Considerations
Jowled breeds often have altered dental anatomy — crowded teeth, malocclusions, and deep gingival pockets where food and bacteria accumulate. The loose lip tissue also traps food debris against the gumline. Plan for:
- Professional dental cleanings under anesthesia every 6–12 months ($300–$800 per session)
- Daily tooth brushing with enzymatic canine toothpaste (e.g., Virbac CET, ~$10–$14 per tube)
- Regular lip-fold inspection during brushing sessions
Common Misconceptions About Dog Jowls
| Myth | Fact |
|---|---|
| "Drooling means my dog is sick or nauseous." | While nausea can cause hypersalivation (ptyalism), most drooling in jowled breeds is anatomical, not pathological. Saliva simply escapes because the lips cannot contain it. However, a sudden increase in drooling in a previously dry-mouthed dog warrants veterinary evaluation. |
| "You can train a dog to stop drooling." | Drooling in jowled breeds is a physiological response to gravity, saliva production, and lip anatomy. No training protocol will change this. You can manage it with husbandry, but expecting a Mastiff to stop drooling is like expecting a Greyhound to stop being fast. |
| "Loose skin means my dog is overweight." | Jowl tissue is primarily dermal collagen and connective tissue, not adipose. A lean Bloodhound still has dramatic jowls. However, obesity can worsen skin fold problems by deepening folds and increasing friction. |
| "All wrinkles need surgical correction." | Most jowl and facial fold tissue is normal breed conformation. Surgery (such as lip-fold resection or cheiloplasty) is only indicated when folds cause chronic, treatment-resistant infections or interfere with eating and breathing. Your veterinarian will determine if surgical intervention is warranted. |
| "Jowls are purely cosmetic and have no function." | In their original working context, jowls served scent-trapping, protective, or thermoregulatory functions. They are not vestigial — they were actively selected for, even if modern pet dogs no longer perform the work that made jowls advantageous. |
When Jowls Signal a Problem: Medical Red Flags
- Sudden, unilateral jowl swelling (one side only) — could indicate abscess, salivary gland mucocele, or neoplasia
- Foul odor from folds that does not resolve with daily cleaning — suggests bacterial or yeast overgrowth requiring prescription treatment
- Pawing at the mouth, reluctance to eat, or dropping food — may signal dental disease, oral mass, or foreign body trapped in the fold
- Thick, yellow-green discharge from fold tissue — indicates active infection needing culture and targeted antibiotics
- Acute increase in drooling volume accompanied by retching, distress, or a distended abdomen — these are emergency signs of gastric dilatation-volvulus (GDV/bloat) or oral trauma
- Visible masses, lumps, or ulcerated areas inside the jowl folds — oral melanoma, squamous cell carcinoma, and papillomas can develop in lip-fold tissue
Lip fold dermatitis (also called lip fold pyoderma) is the most common jowl-related medical condition. It occurs when the lower lip fold creates a dark, moist, warm pocket where bacteria proliferate. Signs include redness, a musty or yeasty smell, brown discharge, and the dog frequently rubbing its face on furniture or carpet. Treatment typically involves topical chlorhexidine or miconazole, and in refractory cases, a surgical procedure called lip fold resection (cheiloplasty) to remove the excess tissue. Costs for cheiloplasty range from $500 to $2,500 depending on the complexity and whether both upper and lower folds are addressed.
Another condition to watch for is salivary mucocele — a fluid-filled swelling that forms when a salivary gland duct is damaged and saliva leaks into surrounding tissue. These typically appear as soft, fluctuant swellings under the jaw or along the jowl line. They are usually painless but require veterinary drainage or surgical excision of the affected gland.
Frequently Asked Questions
Why do some dogs have jowls while others do not?
Jowl development is determined by breed genetics and the selective breeding history behind each breed. Dogs bred for scent work (Bloodhounds) or physical protection (Mastiffs) were selected for loose facial skin because it served a functional purpose. Dogs bred for speed (Greyhounds) or precise retrieval (Labradors) were selected for tight, aerodynamic facial anatomy. The trait is heritable and controlled by multiple genes influencing collagen production, elastin density, and skin attachment to underlying facial structures.
Can dogs with jowls smell better because of them?
There is a functional relationship, though it is indirect. In scent hounds, the long, pendulous jowls and ear leathers create a "scent chamber" near the nose that helps trap and concentrate volatile odor molecules. This does not mean a Bloodhound's olfactory receptors are inherently superior to a German Shepherd's — both breeds have excellent olfaction — but the jowl anatomy in Bloodhounds gives them a mechanical advantage in directing scent-laden air toward the nasal epithelium. Bloodhounds have approximately 300 million olfactory receptors compared to roughly 220 million in a Beagle and about 5–6 million in humans, which is the primary driver of their scenting superiority.
How do dogs with jowls process food differently?
Jowled breeds tend to be messier eaters, not because they process food differently in a digestive sense, but because their lip anatomy fails to create a tight seal around the mouth. Food particles and water escape the oral cavity more easily, and kibble can become trapped in the fold between the lower lip and the jawline. Some heavily jowled breeds also have brachycephalic (short-muzzled) conformation that affects how they grasp and chew food. Using a slow-feeder bowl or a raised food station can reduce mealtime mess, though it will not eliminate it.
What does it mean when my dog's jowls are swollen?
Swollen jowls are not normal breed conformation — they signal a medical issue. Common causes include dental abscesses (especially of the carnassial teeth), salivary gland mucoceles, insect stings or allergic reactions, trauma (bite wounds or lacerations hidden within the fold), or neoplasia (oral tumors). Unilateral swelling (one side only) is particularly concerning for abscess or tumor. Bilateral swelling may suggest an allergic reaction. In all cases, prompt veterinary evaluation is necessary. Do not attempt to lance or drain any swelling at home.
Is excessive drooling from jowls normal, or should I be concerned?
Baseline drooling in jowled breeds is normal and expected. However, a sudden change in drooling patterns warrants investigation. If your Mastiff has always drooled moderately and suddenly begins producing large volumes of thin, watery saliva, possible causes include oral foreign bodies (stick fragments, bone shards), dental fractures, nausea from gastrointestinal disease, heat stroke, toxin exposure, or neurological conditions affecting the salivary nerves. If excessive drooling is accompanied by lethargy, vomiting, difficulty swallowing, or a distended abdomen, seek emergency veterinary care immediately — these can be signs of GDV (bloat), which is life-threatening.
How is jowl anatomy in dogs different from humans?
Humans do not have jowls in the canine sense. While aging humans may develop sagging skin along the jawline (sometimes colloquially called "jowls"), this is age-related dermal elastin degradation, not a functional anatomical structure. Dogs with pronounced jowls have them from birth — the tissue is developmentally programmed by breed genetics. Additionally, canine jowl tissue contains a mucosal inner lining continuous with the oral cavity, integrated salivary duct openings, and cutaneous facial muscles (like the depressor labii inferioris) that have no direct human equivalent in terms of scale and mobility. The dog's jowl is a distinct anatomical structure, not simply loose skin.
Can I reduce my dog's jowls through diet or exercise?
No. Jowl tissue is primarily collagen and connective tissue, not fat. While maintaining your dog at a healthy body condition score (BCS of 4–5 on the 9-point scale) will prevent obesity from deepening folds and worsening skin fold dermatitis, weight loss will not reduce the jowl tissue itself. If jowls are causing chronic medical problems, surgical correction (cheiloplasty or lip fold resection) is the only option, and this should be discussed with your veterinarian or a veterinary dermatologist.
Related Behaviors and Abilities
Jowl anatomy connects to several other canine traits worth understanding:
- Drooling and thermoregulation: Dogs do not sweat through their skin like humans. Panting and saliva evaporation are primary cooling mechanisms. Jowled breeds may drool more in warm weather as part of their thermoregulatory response — this is functional, not pathological.
- Flehmen response: While more studied in cats, dogs also exhibit a rudimentary flehmen response (curling the upper lip to direct scent to the vomeronasal organ). Loose jowl tissue may alter how scent molecules reach this organ.
- Facial expression and communication: Dogs use facial muscles for social signaling — relaxed, open-mouth expressions versus tight-lipped stress signals. Heavily jowled breeds can make facial expressions harder to read, which is one reason these breeds are sometimes misinterpreted as "lazy" or "unresponsive" when they are simply harder to read visually.
- Brachycephalic obstructive airway syndrome (BOAS): Some jowled breeds (Bulldogs, Pugs) also have brachycephalic conformation. While jowls themselves do not cause BOAS, the same selective breeding that produced loose facial skin often shortened the muzzle, creating overlapping respiratory challenges.
Beth Carrasco
All our authors care for dogs every day — read more of their work on the authors page.
