What Does a Tumor Look Like on a Dog?

It is typical to discover bumps in the body of a dog. These masses especially appear in dogs in their senior years. As a dog parent, you should know the types of tumors. Persistent, unusual masses should prompt you to get your dog examined at once. You want to know what does a tumor look like on a dog? It helps you understand if these require vet intervention.

Can Dogs Get Skin Cancer?

What Does a Tumor Look Like on a Dog

Dogs can get skin cancer, just like humans. The most common type of tumor in dogs would be skin cancer. Skin tumors are more visible than any other kind of tumor. The skin is unprotected from environmental variables that cause tumors. In contrast, your dog’s internal organs are not bombarded by these. Thus, cancer tumors are easily detected by you and your vet, which helps you treat it with available options.

Causes of Skin Cancer in Dogs

Skin cancer can be traced to various causes. Similar to people, genes play a huge role in which breeds are likelier to develop skin cancer. Genetics has been known to be the number one factor in the progression of skin cancer in dogs. Cancer is triggered when the dog is exposed to too much sun, chemicals in the environment, hormonal imbalances, and types of viruses.

Difference between Tumors, Growths, and Cysts – What Does a Tumor Look Like on a Dog?

What does a tumor look like on a dog? Many vets will call lumps and bumps masses or tumors. Overall, these terms are interchangeable. But most vets do not use the word tumor unless it has been identified as some cancer.

What are Tumors in Dogs?

Abnormal growths can happen anywhere on a dog’s body, especially in areas around the mouth. The following are the warning signs:

  • Abnormal lumps and bumps that range in size from very tiny to large
  • Discolored, itchy, and irritated skin
  • Swollen areas on the body
  • Large lymph nodes
  • Limp or swelling that affects the bones

Cancerous growths

Sebaceous growth has sebum and oily material. It is typically found in the skin around hair follicles. These masses can grow anywhere on the body. Sebaceous growths are nothing to worry about and are typically benign, but can be a malignant tumor otherwise called sebaceous gland adenocarcinoma. If the cyst doesn’t cause discomfort in your dog, your vet might leave it. But this can be removed surgically if needed. Once it is removed, it should be examined to determine if it is a benign tumor and does not require more treatment.

Skin Protrusions

Skin Protrusions growing on dogs are similar to those of humans. These tags can grow into large and pendulous bulges that hang via a narrow stalk. Skin Protrusions are typically benign and should not be removed unless it causes severe discomfort and irritation.


These growths are red bumps that can grow on your dog’s skin but fade after several months. Although these are benign, it can grow rapidly and cause discomfort in your dog. Your vet may suggest removing these large histiocytomas. In contrast to other skin masses, these frequently grow in younger dogs.

Cell Carcinoma

What does a tumor look like on a dog? These carcinomas are a type of tumor that is caused by exposure to the sun. It is a type of cancer that can grow on the skin and mouth area. These tumors have pink or reddish color as well as a distorted and raw appearance.


Malignant melanomas can grow on the skin and the mouth area. It is thought to be a result of harmful sun exposure. A majority of these tumors will be black colored and will vary in appearance from each other. 

Oral Growths

What does a tumor look like on a dog? These are growths on your dog’s mouth area. Some growths are not obvious but will cause symptoms such as bad breath, trouble chewing, and difficulty holding things in the mouth. You might also find that your dog has oral pain and frequently paw at their nose and mouth. However, these signs may be caused by dental disease and should never be ignored.

Papillomas, otherwise known as warts, are caused by papillomavirus. They can grow on your dog’s lips, face, and inner mouth. Papillomas are noncancerous but extremely contagious. They can be eradicated if it causes discomfort in your dog. In a majority of cases, it resolves on its own.

An epulis are oral growths that grow on the gum tissue near the tooth area. Many of these are noncancerous, but some can be malignant. Examining these tissues are necessary.

Gingival hyperplasia is a noncancerous overgrowth of gum tissues that resemble tumors. These excess tissues can be eradicated if it is affecting the teeth and causing discomfort in your dog. A vet pathologist should examine the sample tissue to ensure there are no cancer cells.

Oral melanoma grows on the mouth and are typically black colored.

Squamous cell carcinomas and fibrosarcoma are other types of cancers that can grow within the mouth of dogs.

There are oral tumors that can affect your dog’s teeth, bone, mouth, and face. If there is an oral mass growing on your dog, your vet will recommend your dog to be put under anesthesia and thoroughly examined with radiographs.

Lipomas in Dogs

Lipomas are types of tumors that grow on dogs. It is a noncancerous fatty mass that can occur anywhere on the dog’s body. Lipomas typically grow under the skin. It feels soft and movable and doesn’t cause discomfort in dogs. Lipomas can be removed surgically if they inhibit your dog’s movement and comfort. Removing it is also recommended if it grows rapidly or ruptures. In some cases, what looks like lipoma is a tumor called liposarcoma. Testing helps distinguish the two.

Cell Tumors in Dogs

What does a tumor look like on a dog? Cell tumors grow on the skin as bumps and internal tumors. These growths release histamine when irritated. It can harm your dog’s body. If your veterinarian identifies the growth as a mast cell tumor, your pet must be treated with diphenhydramine to mitigate the release of histamine. Once the mass is removed, a pathologist will identify the tumor as a 1, 2, or 3. These numbers indicate the tumor’s malignancy and how likely it is to spread to other parts of your dog’s body.

Mammary Tumors in Dogs

Mammary tumors are typical in female dogs, especially if they are not spayed, but they can also grow on spayed females. A minority of mammary masses are noncancerous, but many are cancerous. Prognosis is better when the masses are diagnosed and removed when they are small.

Internal Masses

In some cases, your dog may develop internal masses within the chest and abdomen. It is especially true if they are entering their senior years. You will know your dog is suffering from internal masses from symptoms such as vomiting and difficulty breathing. Your vet might also come across it during a checkup. Internal masses can be either noncancerous or malignant. It can be identified through several diagnostic procedures such as radiographs, ultrasounds, and lab work. The treatment plan will depend on the area and type of tumor.


Lymphomas are cancer of certain cells in the immune system. But a crucial sign of lymphoma is swelling of the lymph nodes, which can resemble and feel like tumors.

Dog owners often observe these lumps in the neck area. But it can also grow in the ancillary area, lower abdomen, and back of the knees. Lymphoma can be diagnosed by extraction with a fine needle or biopsy. Chemotherapy is the best intervention for lymphoma.

Diagnostic Process

What Does a Tumor Look Like on a Dog

Once a lump is discovered, your vet will physically examine your dog. If it is new and possibly temporary, such as bug bites, the vet may recommend observing it for a period. But in a majority of cases, they will perform diagnostics to identify the type of cells within the mass. This means getting a sample of the lump mass and examining it under a microscope.

Typically, a vet collects the samples through a fine needle aspirate or biopsy. The samples will be evaluated, which can indicate if the mass is cancerous. It also helps identify the specific cancer present.

If your veterinarian diagnoses that your dog has cancer, they will require additional diagnostics such as the following:

  • Blood chemistry tests, blood count, urine examination
  • Radiographs which can show metastasis and other issues
  • Ultrasounds which can show a better view of internal structures and signs of metastasis.
  • CT scan and MRIs help vets get a close look at the structure of the dog’s tumors and internal organs.

A vet specialist must do advanced diagnosis and treatments.

When Your Dog Needs a Biopsy

A biopsy is recommended if needle aspirate is not adequate. Biopsies are performed when a dog is under general anesthesia or sedated. But local anesthesia may be utilized depending on the size and area the mass is located.

The biopsy may be done utilizing a special large needle. The vet may cut the mass surgically. The entire mass will be removed surgically and examined in a laboratory.

Preventing Cancer in Your Pet

Consider Spaying or Neutering Your Pet

Spaying your female dog before the first heat cycle mitigates the risk of breast cancer. Spaying requires removal of the ovaries and uterus.

Reduce sun exposure

Exposing your dog to the sun’s harmful UV rays is one of the top causes of skin cancer. Your dog’s furry coat protects them from sun exposure, but those with light-colored fur, especially on the eyes, nose, and ears where there is thin fur, can develop cell carcinomas when exposed under the sun for long periods. Light coated dogs can also develop skin cancer in areas where there is sparse hair. If your dog has a light-colored coat and spends much time outdoors, try to factor in sun protection options.

Quit Smoking

A majority of lung cancers develop due to smoking. Your physician will recommend you quit the habit of mitigating your risk of developing lung, throat, and bladder cancers. But smoking can cause cancer in your pet as well. A dog that lives with owners who smoke has a higher risk of nasal cancer. Dogs exposed to secondhand smoke have a risk of developing lymphoma and cancer cells.

Be an Observant Owner

As a dog owner, you should know that many types of cancers exhibit similar symptoms. But these symptoms can indicate serious diseases other than cancer. When you interact with your pet, check for crucial signs. If you come across something that shows an emergency, make sure to have your dog examined by a vet. You might observe your dog suffers from a loss of energy and lack of interest in physical activity. These are warning signs that something is off. Keep in mind that early diagnosis can help with treatment success. It is true whether your pet has cancer or other types of diseases.

Final Thoughts – What Does a Tumor Look Like on a Dog?

What Does a Tumor Look Like on a Dog

It is crucial to care for and maintain your dog’s health throughout their lives. Check your dog’s body when grooming and bathing them for anything odd such as tumors. What does a tumor look like on a dog? These are growths that feel and look unusual. Make sure to have your dog checked by a veterinarian to ensure the growth is noncancerous. Your vet will recommend treatment interventions based on their diagnosis.

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