Causes of Lumps and Masses in the Mouth in Dogs

Updated on March 16, 2018
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Adrienne is a former veterinary hospital assistant, certified dog trainer, behavior consultant, and author of "Brain Training for Dogs."

Humans are not the only ones to get lumps and bumps on their bodies. Canines also frequently develop odd looking masses and growths.

According to the Pet Cancer Center, oral cancer is the fourth most common cancer overall in dogs. A mass in the mouth can be caused by several conditions, but since there is always a chance that it is cancer, as in humans, any suspected lump or bump should be biopsied to rule out this possibility.

The problem is that owners don't always discover the growths. Sometimes, the growth is hiding under the tongue and can only be seen when the dog keeps the tongue to the side.

Sometimes the lump is in the back of the mouth or on the roof of the mouth. Often, one big cause of alarm is a bump on the roof of the mouth right behind the top front teeth. This often turns out to be an incisive papilla, but at times there can be other growths in these areas too.

It is always recommended for dog owners to inspect their dog's mouth on a frequent basis. The best way to do this is by routinely brushing their teeth.

The following are some of the most common causes of lumps, bumps, or growths in a dog's mouth.

Benign Growth Causes

As scary as growths can be, luckily many are benign. Regardless, all growths should be carefully evaluated by a vet to see whether or not they are harmless or need to be removed.

Canine Viral Papillomas


These are small growths characterized by a jagged surface, resembling a cauliflower or sea anemone in shape. At times, however, they can be smooth.


They are typically found on the lips and muzzles of dogs under the age of two. These papillomas are contagious between dogs and are transmitted with direct contact.


Generally, they go away on their own within five months. While rare, some of these growths do turn malignant, according to Mar Vista Animal Medical Center.


This is the most common type of benign growth found in dogs' mouths. It is also simply known as a gum boil. There are three types of epulis: fibromatous, ossifying and acanthomatous.

Appearance and Location

This growth is the same color of the gums and fairly smooth. It is typically found between the incisors or canine teeth. Sometimes it may present a stalk-like growth.

Who Gets Them

These lumps are generally found in older dogs over the age of six. The Boxer breed and other brachycephalic or short-nosed breeds may be predisposed to it.

Side Effects

As this mass enlarges, it may start causing trouble such as drooling, bleeding, difficulty eating, and bad breath. At times, the growth may cause the teeth to shift and grow misaligned.


A vet will biopsy the growth to rule out cancer and will remove the growth surgically. Prognosis is pretty good for small epulis.

Types of Malignant Mouth Tumors

These are the three most common malignant oral cancers found in dogs. Of dogs with cancer, melanoma affects 30% - 40% dogs, squamous cell carcinoma affects between 17% to 25%, and fibrosarcoma affects 8% - 25% according to Virginia J. Coyle, DVM, and Laura D. Garrett, DVM, DACVIM (oncology).

Malignant Melanoma

This is the most common oral malignancy in dogs. Oral malignant melanoma tends to develop when there is an abnormal cell division of melanocytes.

Location and Side Effects

It typically appears on the gums, the lip, the palate, and sometimes on the tongue of older pets and can cause symptoms such as trouble eating (preferring soft foods), oral bleeding, facial swelling and bad breath.

Who Gets Them

Commonly affected breeds are those with pigmented mouth tissues such as the Chow Chow, however other predisposed breeds are poodles, dachshunds, Scottish terriers and golden retrievers.

These tumors are known for spreading quickly and aggressively to other parts of the body, the preferred site being the lungs and regional lymph nodes.

Squamous Cell Carcinoma

This form of cancer is more common in cats, however dogs occasionally get it as well.

Side Effects

Affected dogs will drool, develop difficulty eating, and have bad breath.


This cancer has a prevalence for developing in the gingiva and is locally aggressive, but may spread late in the disease. If the mass is found in the front part of the mouth, there is a good chance that surgery can cure it, according to Vet Surgery Central Inc.


These are malignant tumors that are locally invasive but may spread to other parts of the body, a process known as ''metastasis."

Location and Appearance

These tumors originate from the fibrous tissue of the mouth and may appear as a red growth or ulcer. These tumors have a tendency to ulcerate and bleed but do not generally spread as quickly as other tumors.

Some less common but also malignant oral tumors found in dogs include osteosarcoma, mast cell tumor, hemangiosarcoma, lymphoma, plasma cell tumor, and multilobular tumor of bone.

Always Get a Vet's Opinion

These are just a few examples of the most common oral growths found in a dog's mouth. Should your dog develop something in their mouth, no matter how small it is, it is best to have a vet take a look at it to rule out the possibility of cancer.

Disclaimer:This article is not to be used as a substitute for veterinary advice. If your dog develops a lump, bump, mass, or growth, have it seen by a veterinarian promptly. By reading this article you accept this disclaimer.

A possible squamous cell carcinoma of the lower mandible in a one-year-old Lab
A possible squamous cell carcinoma of the lower mandible in a one-year-old Lab | Source

Questions & Answers


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      • profile image

        Irène 8 weeks ago

        My little 4lb poodle as a lump growth between his teeth that were pulled by the vet...

        it isn’t tender but is a fair size of it...

        Can you give me any idea of what it is.

      • profile image 9 months ago

        My dog had epulis known as gum boils it was removed and was not canceres.but it grow back again spend a lot of $$ and put her thru hell. Any suggetions what to do?

      • profile image

        Diane 9 months ago

        My German Shepherd one yr. old has a small white bump on his tongue. What is this?

      • profile image

        Margaret Burke 14 months ago

        My boxer has developed black on his lower gums ??? Can you advise????

      • profile image

        Leo 14 months ago

        Few days ago I just notice a mass on the side of my dog canine teeth . So I tried to open his mouth to figure it out,so I feed him water then a small piece of mass came out Form this mouth so I try to pulled it and the whole chunk of mass came out I was so glad . From that insident I always brush his teeth and check his mouth . But still the symptoms is there so if any one dog has recover form this can u give me tips pls.

      • profile image

        heathar 22 months ago

        Our 7 month old pup has a growth under her tongue with white dot like bumps on one side and it appears to have white inside it. last seen by Vet two weeks ago and put her on watch. nothing changed. she has referred us to go to the University of Guelph to have this looked at. today she has started our pup on antibiotics to see if this helps. They are suggesting it could be a blocked gland.

      • profile image

        Candice 2 years ago

        I have a two month old chihuahua, shih tzu mix. Just a few days ago i noticed a lump on the side of his face, cheek area. It seemed to be tender to the touch. Within a matter of a few days it seemed to swell up but didn't seem so tender. My husband checked the inside of his mouth and on the rear right side of his mouth was a lump that is red, with mild bleeding, sore the size of a tip of a qu-tip but is really swollen behind it. Just wondering what may have caused this and if there is anything we can do about it? Can this be serious and dangerous?

      • alexadry profile image

        Adrienne Janet Farricelli 2 years ago from USA

        It might be the incisiva papilla but not necessarily. Have it checked out by your vet to play it safe. Here's about the incisive papilla in dogs.

      • profile image

        sandy 2 years ago

        We have a 3yr old german shepherd that seems to have a small bump just behind his top front teeth roof of his mouth. Is this normal?

        A little background is he got into snail bait out in thecshed at 6 weeks old, we got him through this and a couple months ago he started having seizures. He is on phenobarbital but other than this he is good dog. He is the old fashioned german shepherd with straighter back and quite active.

      • profile image

        Tim 2 years ago

        We have an 18 1/2 year old terrier mix with a fairly large gum boil between his lower lip and teeth. Fortunately, it does not interfere with his eating and he has a big appetite. He doesn't seem to be bothered with it except he often rubs the area on the rug. It sometimes bleeds but not severely. The vet doesn't seem to want to do anything about it. I was wondering how big these boils get and if there's anything I can do at home.

      • alexadry profile image

        Adrienne Janet Farricelli 3 years ago from USA

        Sorry, I really can't help, only your vet can tell exactly what it is. It's sort of like with human masses and lumps. Nobody can tell what a lump in a women's breast is and the same is with dogs. You'll find that even vets won't diagnose by looking at a lump alone, they'll have to do a biopsy to determine what it is. I hope it's something minor.

      • profile image

        Alexandra 3 years ago

        Hi my dog has a rounded lump the size of a pea on his tongue. I just noticed it. It doesn't look sore. It's the same color as the rest of the tongue. Can you help please?

      • alexadry profile image

        Adrienne Janet Farricelli 3 years ago from USA

        At this age, cancer should be uncommon, but not unheard of, more common lumps are papillomas. Did the vet prescribe antibiotics and see if the growth shrinks? Can you have your pup go see a veterinary oncologist? A specialist may be better able to help you out.

      • profile image

        jimal linder 3 years ago

        My thirteen month pup he is mastiff an chow chow mix he has a very big growth on his front lip I'm scared to death for him I took him to the the vet and they said it could be cancerous What more can I do I have his meds prescribed to him what do I do?

      • alexadry profile image

        Adrienne Janet Farricelli 4 years ago from USA

        Oh ,my what type of tumor? Did the vet do a biopsy on it? Does he have any other symptoms? Maybe get a second opinion. When my dog had a lump on her paw, I saw 3 different vets and they told me 3 different things. I used a free vet visit from VCA animal hospital too, so had nothing to lose. If you google VCA free exam, you can fill a form out and get a free visit if you are a new client. Also, a holistic vet can also help too.

      • profile image

        josie 4 years ago

        I have a golden retriever he is 6yrs. old and yesterday the vet told me he has a tumor in the mouth. My Buddy is not feeling very well!! The vet told me that the best option is to put him to sleep!!! Not prepared for that one, love my dog and my kids are devastated!!! What can I do!!!

      • alexadry profile image

        Adrienne Janet Farricelli 5 years ago from USA

        The surgery may prevent cancer from spreading if caught in the early stages. That's what my vet said and why he removed it from my lab. Best wishes!

      • profile image

        Andrea Foncerrada 5 years ago

        I have a 12 year old chow. She has a little mass on her tongue since last august. We decided not to do any surgery until it was absolutely necessary. It might be time because she is starting to have difficulty eating. If it is cancer, we won`t do chemotherapy or other treatments. We are only concerned of increasing her quality of life. Will the surgery increase it or decrease it? Any help?

      • alexadry profile image

        Adrienne Janet Farricelli 5 years ago from USA

        I hope it turns out being just a papilloma, fingers crosses. Lumps and masses in dog mouths can be scary.

      • profile image

        Mollysmom 5 years ago

        I have a wonderful golden named Molly, she just turned 7yrs. old 10/11/12. We took her to the vet 3 wks ago, because she has a white round growth towards the tip of her tongue, vet put her on Pregnazone steroids, says he's 95% sure its cancer, I'm holding out hope that its some type of a viral wart Thank god she has no fluid coming from it, no bad breath, no problem eating or drinking, so we're hoping for the best. A needle bipsy is going to be performed this Fri.10/10, hoping for the best.

      • alexadry profile image

        Adrienne Janet Farricelli 5 years ago from USA

        So sorry to hear that. The vet offered no option of removing the mass in your dog's mouth surgically?

      • profile image

        Lab Owner 5 years ago

        My 11 year old labrador has a growth on his top gum mouth and it's growing into the roof of his mouth. He had a tooth removed as the vet believed that it was irritating the growth. That growth has now doubled in size. She has assured us that it wasn't cancerous in any way shape or form. My labrador is now very ill as this growth has length sessions of bleeding every now and again. He has been sick, bringing up old blood, fresh blood from the growth and a white fluid. He's very lethargic and is showing signs of anemia. If there is no improvement, we will be letting him go tomorrow.

      • alexadry profile image

        Adrienne Janet Farricelli 6 years ago from USA

        Linda, don't over worry, the lump does not have to necessarily have to be something worrisome. My vet assumed the worst but then it turned out being only an oral papilloma. I know it is easier said than done, but try to relax and wait for Monday. If she is young and you just noticed this, chances are good it may be nothing major. Fell free to post back your vet's finding to share with others in your same situation. Best wishes!

      • profile image

        Linda 6 years ago

        I just noticed a red mass in the back of my lab's mouth. Her breath has been bad lately but associated it with her snacking on deer droppings in our back yard. The more I read the more I cry. I will get her to the vets on Monday. Also last night after playing and running i noticed her breathing wheezing. With wjat is in tbe back of her throat it now makes sende. Anyone have seen this or cooments while I wait to get her to the doctor. Thank you and happy new year 2012.

      • alexadry profile image

        Adrienne Janet Farricelli 6 years ago from USA

        Alicia, my vet tentatively assumed the worse, but after removing the lump noticed its jagged surface and said it was a papilloma.

      • profile image

        Alicia Nuss 6 years ago

        My lab has a mass under her tongue and others about her body .The one in her mouth looks very similar to this pic, thanks, now I am afraid to take her to the vet again she is my baby.Pug Lady I am so sorry about ur baby.Waggin Tails Mobil Pet Grooming

      • MarloByDesign profile image

        MarloByDesign 6 years ago from United States

        puglady, that breaks my heart. I am truly so very sorry.

      • profile image

        puglady 6 years ago

        3 1/2 weeks ago my 12 yr. old pug had her teeth cleaned and an epulis removed. Vet did chest x-ray and told me 'best heart he's ever seen in an older pug'. Lab work came back perfect !! Thyroid, etc...all 'normal range'.

        Noticed a few days ago difficulty eating and lymph nodes swollen . Opened mouth and saw LARGE growth on roof of tongue!! Just got back from vet. He was shocked. Immediately diagnosed with 'oral cancer'. I will being putting my baby girl down on Monday.

      • SUSIE DUZY profile image

        SUSIE DUZY 7 years ago from Delray Beach, Florida

        Thanks for this good information.

      • marcoujor profile image

        Maria Jordan 7 years ago from Jeffersonville PA

        Thank you for this well written information. A student recently discussed a mass that was found in her dog's mouth, and the picture was unbelievable. I will share this with her as well.

        Voted UP & USEFUL!

      • MarloByDesign profile image

        MarloByDesign 7 years ago from United States

        Thank you for writing a Hub to help make dog owners aware of these canine mouth issues - as a dog lover, this is great. Please feel free to visit my Hub on 'Saving Money for Dog Owners'. Rated your Hub up and awesome.


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