Causes of Swollen Lips in Dogs

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If your dog has folds around his mouth, keep them clean and dry.
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You love your pup's sweet face, but when something's not quite right with it, it's cause for alarm. If your dog has a fat lip, it may be from a tussle with another dog, a cat or even an insect. Other potential causes of a dog's swollen lip include infection, dental disease, and tumors.


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Look for bites and stings

Dogs are curious, busy creatures, often following their noses wherever they're led. If your pup stuck his sniffer in the wrong place, he might have encountered a bee or a spider that took offense to his interest.


Stings and bites can cause a dog's swollen lip and if your dog has a severe allergic reaction, his throat may swell also, cutting off his ability to breathe. If the swelling expands and he has trouble breathing, don't wait for your dog to pass out to seek veterinary treatment. Dog swollen lips can be a vital first sign of a potentially dangerous reaction. If he's suffering from an allergic reaction, antihistamines and steroids may be part of his treatment plan.


Check for oral growths

Cancerous and noncancerous growths can cause dog's swollen lip. Oral growths that can affect your dog's lips include viral warts, slower growing papillomas, epulides, and cancerous tumors such as squamous cell carcinoma.


If your pup has a tumor in his mouth, he'll likely have problems eating; other symptoms include bleeding and unpleasant odor. Whether benign or malignant, tumors require early treatment to stop the growth, though viral warts may disappear on their own.

Sniff out dental problems

Dental problems can give your dog a swollen mouth or lips. An infected tooth will cause swelling, as well as fever and depression. Severe gum disease and inflammation inside the mouth, such as ulcerative stomatitis, can cause inflammation of the lips.


Dental conditions are painful, often showing symptoms such as reluctance to eat, pawing at the mouth, bad breath, and blood-tinged saliva. Treatment depends on the condition, and may include tooth extraction, dental cleaning, and antibiotics to clear up an infection.

Investigate infection from injury

In addition to an inquisitive nature, dogs love to snipe at anything that just might taste good. That means he may snag something that is apt to cut his mouth, such as a sharp plant, resulting in inflammation and sores in his mouth. Other symptoms of a mouth injury might include blood in his saliva, drooling, and bad breath.


A chance encounter with another dog, cat, or another animal may result in an infected puncture wound, also known as cellulitis. Signs of an infection include swelling, redness, tenderness or pain, and ulcers. He'll need a trip to the vet to get his wound cleaned and antibiotics to clear up any infection.


Clean deep lip folds

If your dog is a breed with a drooping upper lip and lower lip fold, such as an English bulldog or Saint Bernard, he may experience a skin inflammation known as lip fold dermatitis. The lips are prone to accumulating moisture, causing swelling, inflammation, and foul odor.


Keeping on top of your dog's oral hygiene is important, meaning his lip folds should be cleaned once or twice a day with a mild cleanser. As well, his mouth should be kept dry to keep moisture from collecting in the folds. In severe cases, deep lip folds may be corrected surgically.

Consider other causes

If your dog hosts the wrong tick, he can become infected with rickettsia rickettsii, the organism causing Rocky Mountain spotted fever. In the acute stage, this condition carries symptoms such as fever, depression, loss of appetite, joint and muscle pain, and fluid accumulation in the face and legs. Timely veterinary treatment is necessary for a full recovery and requires antibiotic therapy. Other supportive care, such as fluid therapy, may be required, depending on the dog's condition.

Some breeds of dogs, such as boxers, Doberman pinschers, and Labrador retrievers, experience a rare condition known as craniomandibular osteopathy, causing swelling in the jaw. The condition tends to develop in dogs less than a year old, and include other symptoms such as drooling, reluctance to eat, and fever. It often stabilizes around the age of one year, and anti-inflammatories help to manage the associated pain.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.