# Bumps on Your Dog's Lips and Mouth: Causes and Care A dog bump on the lip is usually a wart-like papilloma, a cyst, or a benign growth, but it can also be a tumor that needs treatment. Because mouth lumps are easy to see but hard to identify by eye, a veterinarian should examine anything that persists, grows, or bleeds. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Most small, slow-growing lip bumps in young dogs are viral papillomas that often resolve on their own within weeks to a few months. - Any lump that grows quickly, bleeds, smells bad, or interferes with eating, drinking, or breathing needs prompt veterinary attention. - Tumors of the skin and tissue just under the skin are the most common tumors seen in dogs, and the mouth and lips are no exception [1]. - Lip fold dermatitis is a separate problem that causes swollen, bad-smelling, inflamed lower lip folds in breeds with droopy lips, such as spaniels, English Bulldogs, and Saint Bernards [2]. - Never try to pop, cut, or tie off a mouth lump at home. Your veterinarian needs to see the tissue intact to diagnose it. ## What a Dog Bump on the Lip Looks Like and What Is Normal Dogs get bumps on the lips, gums, tongue, roof of the mouth, and cheeks for many reasons. Some are harmless and some are serious. The tricky part is that they can look almost identical at first. A normal mouth should be pink, smooth, and moist. The lips should sit comfortably against the teeth without sores or swelling. Small, pale, raised spots on the inner lip where it touches the teeth can be contact ulcers, sometimes called "kissing ulcers," because they form where the lips "kiss" the teeth [2]. These are not tumors, but they still need a veterinarian to sort out the cause. You may also notice a dog bump on the skin elsewhere on the body, which can be unrelated to the mouth. If you are seeing bumps in more than one place, it helps to read about [Dog Skin Bumps and Lumps: When to See the Vet](/knowledge/veterinary-medicine/vet-visit-decisions/dog-skin-bumps-lumps) so you can track what is new and what has been there a while. ### Common places owners find mouth bumps - Inner surface of the upper lip, near the canine or carnassial teeth - Lower lip folds, especially in droopy-lipped breeds - Gums along the tooth line - Roof of the mouth (hard or soft palate) - Cheek lining next to the molars - Tongue, especially underneath A dog bump on the roof of the mouth or a dog bump on the cheek can be harder to see. You might only notice it because your dog drools more, chews on one side, or drops food. ## Main Causes of Bumps on a Dog's Lips and Mouth The table below groups the most common causes by what you are likely to see and how quickly you should act. This is a guide, not a diagnosis. | Cause | Typical clues | How urgent | |---|---|---| | Viral papilloma (wart) | Small, cauliflower-like, often in young dogs, may come and go | Routine visit unless it grows fast or bleeds | | Cyst or mucocele | Smooth, soft, fluid-filled, slow growing | Routine visit | | Lip fold dermatitis | Swollen, red, bad-smelling lower lip folds in droopy-lipped breeds [2] | See vet soon, can become painful | | Contact ulcer (kissing ulcer) | Sore where lip meets tooth, often in Greyhounds and some other breeds [2] | See vet soon | | Benign skin tumor | Firm or soft lump, slow growth, no pain | Routine visit with sampling | | Malignant tumor | Rapid growth, irregular shape, bleeding, ulceration | Urgent, same week or sooner | | Histiocytic disease | Multiple raised or flat bumps, sometimes on the face [1] | See vet soon | | Lymphoma or sarcoma | Oral mass, sometimes with lameness or bone changes [3][4] | Urgent | ### Papillomas and warts Papillomas are the classic "dog bump on lip" in a young dog. They are caused by papillomavirus and often look like tiny cauliflowers. A papilloma was confirmed in a dog that developed an oral nodule a year after surgery for an unrelated tumor, and testing was positive for papillomavirus [5]. Most papillomas in young dogs regress without treatment, but your veterinarian may want to confirm the diagnosis if the bump is large or unusual. ### Cysts and mucoceles Cysts are fluid-filled sacs. They tend to be smooth and soft. A mucocele forms when a salivary gland duct leaks saliva into surrounding tissue. These are usually not cancer, but they can get large enough to bother your dog. ### Lip fold dermatitis This is a skin problem, not a tumor. It happens in breeds with drooping upper lips and lower lip folds, such as spaniels, English Bulldogs, and Saint Bernards [2]. Moisture collects in the folds, and bacteria grow. The folds can become very bad-smelling, inflamed, uncomfortable, and swollen [2]. Poor oral hygiene makes it worse because saliva carries more bacteria [2]. ### Contact ulcers and stomatitis Canine stomatitis is inflammation of the mouth lining. Signs include severe gum inflammation, receding gums, and large sores near the big teeth [2]. The contact ulcer forms where the lip rubs the tooth, most often the inner upper lip next to the upper canine and carnassial teeth [2]. Blood tests and tissue samples help rule out other causes such as advanced kidney disease [2]. ### Tumors Tumors are abnormal growths of cells. Tumors of the skin or the tissue just under the skin are the most commonly seen tumors in dogs [1]. They are diagnosed often because they are easy to see and because skin is constantly exposed to things that can cause tumors, including chemicals, solar radiation, and viruses [1]. Hormonal and genetic factors may also play a role [1]. Some tumors are benign. Others are malignant and can spread. An 8-year-old Golden Retriever with an oral mass and lameness was diagnosed with atypical lymphoma, and chemotherapy led to remission and improvement of the oral mass and bone lesions by day 142 after admission [3]. In cats, oral histiocytic sarcoma can invade the jawbone and spread to lymph nodes, which shows why early evaluation matters for any oral mass [4]. Merkel cell carcinoma, a malignant skin tumor, can be confused with other skin growths in young dogs, though it often has a good prognosis after complete surgical removal [5]. Cutaneous histiocytosis causes numerous raised or flat bumps in the deep skin or fat [1]. It is rare, can occur at any age, and is most common in young adults [1]. Certain breeds may have higher risk, including Chinese Shar Peis, Collies, Border Collies, Shetland Sheepdogs, Briards, Bernese Mountain Dogs, Golden Retrievers, and German Shepherds [1]. The bumps may come and go and usually do not itch [1]. They can affect the face and cause trouble breathing if they involve the nostrils [1]. If your dog has bumps on the body along with the mouth lump, the article [Why Is My Dog having lumps on skin? Lipoma vs Mast Cell vs Cyst Diagnosis](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-lumps-on-skin-lipoma-vs-mast-cell-vs-cyst-diagnosis) explains how veterinarians tell these apart. ## Red Flags That Make a Mouth Lump an Emergency Some mouth bumps can wait a few days. Others cannot. Call your veterinarian right away or go to an emergency clinic if you see any of these. - Your dog cannot eat, drink, or swallow. - The lump is bleeding and will not stop. - Your dog is pawing at the mouth, crying, or showing severe pain. - There is swelling under the jaw or down the neck. - Your dog is having trouble breathing. - The lump grew noticeably in a few days. - You see a large sore or ulcer that is not healing. - Your dog is drooling heavily or dropping food. - There is a foul smell from the mouth that is new. - Your dog seems weak, lethargic, or is losing weight. A mass on the soft palate can cause voice changes and reluctance to chew hard food, as seen in a cat with oral histiocytic sarcoma [6]. Dogs can show similar signs. Any of these signs means the lump is affecting function, and that moves it into urgent territory. ## Safe Things You Can Do at Home While Waiting You cannot diagnose a mouth lump at home, but you can keep your dog comfortable and avoid making things worse. ### Do - Take clear photos of the bump from a few angles, with good light. - Note the date you first saw it and measure it with a ruler if you can do so safely. - Write down anything else that changed, such as appetite, drooling, breath odor, or chewing on one side. - Keep meals soft if chewing seems painful. Canned food or soaked kibble can help. - Offer fresh water often. - Keep the lip folds clean and dry if your dog has droopy lips. A veterinarian can recommend a safe wipe or cleanser. - Use a soft cloth to gently dry the folds after meals if your dog tolerates it. ### Do not - Do not squeeze, pop, or puncture the bump. - Do not tie string or thread around it. - Do not apply human acne creams, hydrogen peroxide, or alcohol to the mouth. - Do not give human pain medications. Many are toxic to dogs. - Do not wait months to see if it goes away on its own. If your dog is vomiting or licking the lips more than usual, that can be a sign of nausea or mouth discomfort. The article [Dog Vomiting and Licking Lips: What It Means and What to Do](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-vomiting-licking-lips) covers that pattern. Constant licking of the paws and lips together can also point to irritation or allergy, which is discussed in [Dog Keeps Licking Paws And Lips](/knowledge/veterinary-medicine/clinical-methods/dog-keeps-licking-paws-and-lips). ## What Your Veterinarian Will Check and Test Your veterinarian will start with a full oral exam. This often requires gentle restraint or sedation, because most dogs will not hold still for a thorough look at the back of the mouth. ### The physical exam The veterinarian will look at the lips, gums, tongue, palate, cheeks, and back of the throat. They will check the teeth for sharp edges or disease that could be causing a contact ulcer [2]. They will feel under the jaw and down the neck for enlarged lymph nodes or swelling. They will also check the rest of the skin for other bumps, since skin tumors are the most common tumors in dogs [1]. ### Tests your veterinarian may recommend - Fine needle aspiration: a thin needle collects cells from the lump for review under a microscope. - Biopsy: a piece of tissue is removed and sent to a lab. This is the most reliable way to know what the lump is. - Blood work: checks for infection, inflammation, and organ problems. Blood tests can help rule out other causes of stomatitis such as advanced kidney disease [2]. - Dental X-rays or imaging: looks at tooth roots and bone. In one case, CT showed bone destruction and abnormal tissue in the ear canal area, which helped explain a jaw mass [7]. - PCR testing: can detect papillomavirus in a wart-like growth [5]. ### Treatment depends on the diagnosis Benign warts may need no treatment. Cysts may be drained or removed. Lip fold dermatitis is managed with cleaning, drying, and sometimes medication [2]. Tumors are usually removed surgically, and the tissue is sent for lab review. Some cancers need chemotherapy or other treatment. In one dog with atypical lymphoma, multi-drug chemotherapy led to remission and improvement of the oral mass and bone lesions [3]. In a cat with oral histiocytic sarcoma, surgery reduced the mass but did not remove it completely, and chemotherapy was started afterward [6]. Your veterinarian will tailor the plan to your dog. ## Prevention and Monitoring You cannot prevent every mouth lump. You can improve the odds of catching problems early. - Check your dog's mouth at least once a month. Lift the lips and look at the inner surfaces. - Brush your dog's teeth with pet-safe toothpaste. Good oral hygiene lowers bacterial counts that worsen lip fold problems [2]. - Dry the lip folds after meals in droopy-lipped breeds. Moisture drives lip fold dermatitis [2]. - Keep up with dental cleanings and exams. - Track any bump with a photo and a date. Growth over weeks matters more than size alone. - Limit sun exposure for light-skinned dogs, since solar radiation is one cause of skin tumors [1]. - Ask your veterinarian about breed risk if you have a Chinese Shar Pei, Collie, Border Collie, Shetland Sheepdog, Briard, Bernese Mountain Dog, Golden Retriever, or German Shepherd [1]. If your dog has a rash with bumps instead of a single lump, the article [Dog Skin Rash with Bumps: What Could It Be?](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-skin-rash-with-bumps) can help you tell the difference. ## Limitations and When to Contact a Veterinarian This article cannot tell you what your dog's lump is. Only a veterinarian can do that, ideally with a sample of the tissue. Individual cases need a veterinarian, and the timing below is a guide. Contact your veterinarian the same day if: - The lump is new and growing. - Your dog is drooling more or chewing on one side. - The lip folds are swollen, red, or bad-smelling [2]. - There is a sore where the lip meets a tooth [2]. - Your dog has other new bumps on the body [1]. Go to an emergency clinic now if: - Your dog cannot breathe, eat, or drink. - Bleeding will not stop. - There is rapid swelling of the face, jaw, or neck. - Your dog is in severe pain or collapses. Schedule a routine visit if: - The bump is small, slow-growing, and your dog is eating and acting normally. - You want a baseline check and a plan for monitoring. ## Frequently Asked Questions ### Is a bump on my dog's lip always cancer? No. Many lip bumps are papillomas, cysts, or contact ulcers. Tumors of the skin and tissue under the skin are common in dogs, but many are benign [1]. A veterinarian can sample the lump to tell you which one you are dealing with. ### Will a dog lip wart go away on its own? Often, yes. Viral papillomas in young dogs commonly regress without treatment. A papilloma was confirmed in one dog and was linked to papillomavirus on testing [5]. If the wart grows quickly, bleeds, or bothers your dog, your veterinarian may recommend removal. ### Can I pop a cyst on my dog's lip? No. Popping or squeezing can cause infection, bleeding, and pain, and it can make the tissue harder to diagnose. Let your veterinarian decide whether the cyst needs to be drained or removed. ### Why does my dog's lip fold smell bad? Lip fold dermatitis is the usual reason. Moisture collects in the folds of droopy-lipped breeds, and bacteria grow, causing a strong odor, redness, and swelling [2]. Cleaning and drying the folds, plus treatment from your veterinarian, usually helps. ### How do veterinarians tell a benign lump from a malignant one? They take a sample. Fine needle aspiration collects cells, and a biopsy removes a piece of tissue for lab review. Imaging such as X-rays or CT may be used if bone or deeper tissue is involved [7]. The lab result guides treatment. ### Should I worry about a bump on the roof of ## Related Articles - [Dog Skin Rash with Bumps: What Could It Be?](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-skin-rash-with-bumps) - [Dog Skin Bumps and Lumps: When to See the Vet](/knowledge/veterinary-medicine/vet-visit-decisions/dog-skin-bumps-lumps) - [Dog Vomiting and Licking Lips: What It Means and What to Do](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-vomiting-licking-lips) - [Why Is My Dog having lumps on skin? Lipoma vs Mast Cell vs Cyst Diagnosis](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-lumps-on-skin-lipoma-vs-mast-cell-vs-cyst-diagnosis) - [Dog Keeps Licking Paws And Lips](/knowledge/veterinary-medicine/clinical-methods/dog-keeps-licking-paws-and-lips) - [Dog Skin Bumps: Comprehensive Veterinary Reference Guide](/knowledge/veterinary-medicine/dermatology/dog-skin-bumps) ## References 1. [Tumors of the Skin in Dogs - Dog Owners](https://www.merckvetmanual.com/dog-owners/skin-disorders-of-dogs/tumors-of-the-skin-in-dogs). Merck Veterinary Manual. 2. [Disorders of the Mouth in Dogs - Dog Owners](https://www.merckvetmanual.com/dog-owners/digestive-disorders-of-dogs/disorders-of-the-mouth-in-dogs). Merck Veterinary Manual. 3. [A case of atypical canine lymphoma with oral mass and multiple osteolysis](https://pubmed.ncbi.nlm.nih.gov/17917387/). The Journal of veterinary medical science, 2007. 4. [Oral histiocytic sarcoma in a cat with mandibular invasion and regional lymph node metastasis](https://pubmed.ncbi.nlm.nih.gov/34777847/). JFMS open reports, 2021. 5. [Diagnosis and treatment of Merkel cell carcinoma in a puppy: A comparative oncology approach](https://pubmed.ncbi.nlm.nih.gov/42266333/). The Canadian veterinary journal = La revue veterinaire canadienne, 2026. 6. [Oral histiocytic sarcoma in a cat](https://pubmed.ncbi.nlm.nih.gov/33282334/). JFMS open reports, 2020. 7. [Infected oral squamous cell carcinoma associated with purulent otitis media in an adult pet rat (Rattus norvegicus)](https://pubmed.ncbi.nlm.nih.gov/41929735/). The Canadian veterinary journal = La revue veterinaire canadienne, 2026. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)