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Why Does My Dog Have Bumps on Its Mouth? (4 Reasons Why It Happens)

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Bumps and lumps on dogs’ mouths it’s not normal. There are many causes, but the most common is oral papillomas, a benign tumor caused by a virus. Other causes that lead to bumps and lumps on the mouth include skin infections, allergies, acne, cancer, or epulis. Contact the vet if your dog has a growth on or in its mouth.

Medical conditions that occur in the mouth can be harmless or severe. They often affect dogs’ eating and drinking, which is troubling. 

In some benign diseases, such as papillomatosis, growths develop in the mouth and esophagus, preventing dogs from eating properly.

In other medical conditions, such as cancer, intervention is critical as it can spread to the rest of the body, leading to the development of metastases in different organs. Cancer can also lead to death.

Keep on reading to learn why your dog has bumps on or in its mouth, what the symptoms are, what to do, and more.

Why Does My Dog Have Bumps on Its Mouth?

Bumps on or in dogs’ mouths are caused by acne, epulis, papillomatosis, cancer, and other conditions. Contact the vet if your dog has one or more bumps on its mouth as not all bumps are harmless or benign.

Dogs often have unusual-looking growths all over their bodies, including their mouths. They can get bumps and lumps on their mouths for many reasons:

  • Epulis
  • Papillomatosis
  • Cancer
  • Acne

While if some breeds are more prone to developing these conditions, they can occur in any breed. 

Older dogs are more prone to developing bumps and lumps, but they can occur at any age.

Oral cancer is said to be the fourth most common type of cancer in dogs. For this reason, it is recommended to go to the vet as soon as you discover a growth on and in your dog’s mouth. The vet will examine it and send it to a lab for a biopsy to rule out cancer.


Why Does My Dog Have Bumps on Its Mouth

Epulis is a benign tumor that mainly develops on dogs’ gums between the teeth, looking like a bump. Older dogs are more affected than young dogs. Treatment consists of the surgical removal of the tumor.

Epulis is the most common benign tumor found in the mouth of dogs. There are several reasons why dogs are affected by this condition:

  • Predisposing factors: Age and certain breeds (Boxer, Cane Corso, Bichon).
  • Local: Tartar, untreated dental fractures.
  • General: Metabolic disorders and hormonal imbalances.

Not all dogs are affected in the same way. There are three types of epulis, each with its on characteristics:[1]

  • Fibromatous
  • Ossifying 
  • Acanthomatous

The symptoms of epulis in dogs include:

  • Bleeding from the affected area
  • Difficulty chewing and drinking
  • Hypersalivation
  • Bloody saliva
  • Loss of appetite
  • Weight loss
  • Pink growths, ulcerated or not
  • Swelling of the jaw bone
  • Bad breath
  • Tooth loss

Sometimes they can grow so much that they can come out of the mouth

Fibromatous Epulis

This type develops as a pink bump with a smooth surface, resembling a mushroom. It usually appears near the incisors, canines, or premolars.

Ossifying Epulis

This type is similar in appearance to fibromatous epulis, but the ossified epulis also has bone cells in its composition. Ossifying epulis can turn cancerous.

Acanthomatous Epulis

Acanthomatous epulis or acanthomatous ameloblastoma is an aggressive condition that also affects the bone. This type of benign tumor can turn into a cancerous tumor, but it is rare. 

Unlike the other two types, acanthomatous epulis bumps are irregular, cauliflower-like, and ulcerated.

Treatment Options

Treatment Options for dog

The treatment of epulis is as follows, depending on the type of epulis:

  • Fibromatous epulis: Surgical removal of the tumor mass, dental extractions, and scaling.
  • Ossifying epulis: Same as fibromatous epulis.
  • Epulis acanthomatous: Surgical removal of the tumor mass, including removal of the affected area (bone) of the upper or lower jaw.

In inoperable cases of epulis, radiotherapy is used as an alternative treatment.

Oral Papillomatosis

Papillomatosis is caused by a papillomavirus. This disease is contagious and is transmitted from dog to dog. It has three forms: mucous, cutaneous, and inverted cutaneous.

Papillomatosis is caused by a papillomavirus, a DNA virus that replicates in the cell nucleus.[2] It produces papillomas (or warts) on different body parts, including in the mouth and esophagus.

Papillomas have a nodular surface, similar to cauliflowers. They are white, gray, or skin color, forming in single instances or in grouped clumps. 

The grouped form generally appears in young dogs.

Papillomatosis is mainly transmitted through direct contact with infected dogs, but can also be spread through contaminated objects or insects.

There are three types of papillomas in dogs:

  • Mucous: Warts appear on the mucous membranes, especially in the mouth.
  • Cutaneous: Warts appear all over the body, including the mouth, especially in old dogs.
  • Inverted cutaneous: Warts mainly appear on the abdomen and legs.

The symptoms of papillomatosis in dogs:

  • Single or multiple growths on the skin, including in and on the mouth
  • Hypersalivation
  • Bloody saliva
  • Discomfort
  • Foul odor coming from the mouth

Take your dog to the vet if it has warts on its tongue, gums, lips, or other areas of the body.

Oral Papillomatosis

Treatment Options

Papillomas usually heal by themselves within 1–2 months of formation if your dog has a strong immune system.

If they do not heal on their own or multiply, vets will surgically remove them.

Related Article: White Bumps on Dog Lips


Oral cancers can manifest as bumps on or in the mouth. Malignant melanomas are the most common type of tumor in the mouth. Other types of cancer that can appear in the mouth are squamous cell carcinoma and fibrosarcoma.

The most common types of tumors[3] that develop in or on dogs’ mouths are as follows:

  • Malignant melanoma: 30-40%
  • Squamous cell carcinoma: 17-25%
  • Fibrosarcoma: 8-25%
Type of tumorMalignant melanomaSquamous cell carcinomaFibrosarcoma
LocationGums, lips, palate, and tongue.It is most often found on the gums but it can also appear on the mouth.It most often appears on the oral mucosa.
SymptomsThe presence of a growth, difficulty chewing, bloody saliva, bad breath, and facial swelling.The presence of a growth, difficulty chewing, bloody saliva, and bad breath.The presence of a red, ulcerated growth (sometimes), foul-smelling breath, and bloody saliva.

Keep in mind that malignant tumors advance quickly. They are aggressive, invading, and metastasizing, reducing your dog’s lifespan and quality of life. 

It is advised to seek the vet’s help as soon as possible.

Cancer on dogs mouth

Treatment Options

The treatment options for oral cancers are not varied. The main treatment option is the surgical removal of the tumor. 

If the tumor has also caught the mandible bone or is infiltrated deeply into the surrounding tissues, the vet can recommend mandibulectomy (removal of a smaller or larger portion of the mandible bone).

In other cases chemotherapy or radiotherapy can be recommended in addition to surgical treatment, depending on the severity.


Acne appears as small red bumps on and around your dogs mouth. It is not a severe medical condition and It does not endanger your dog’s life. It occurs especially in young dogs and certain breeds and can disappear quickly if the pets are well cared for.

Acne mainly affects dogs 5–8 months old, where the hair follicles become inflamed and irritated. Some dogs are prone to acne:[4]

  • Short hair breeds (Boxer, Bulldog, Rottweiler, English Bulldogs, Great Danes, German Shorthaired Pointers, and others)
  • Dogs with poor hygiene
  • Dogs suffering from allergies

Symptoms of acne in dogs include:

  • Breakout on lips, chin, and muzzle (looks like pimples)
  • Severe pain
  • Inflammations and infections, which lead to scars and skin lesions

Treatment Options

In mild cases, the veterinarian can recommend creams and ointments based on benzoyl peroxide (a derivative of hydrogen peroxide). [6] In more severe cases, in addition to these local ointments, steroids can be recommended to reduce skin inflammation.

In other cases, topical and oral antibiotics can also be prescribed.

About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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