Treating and Preventing Dog Skin Cancer

By Chelsea Hunt-Rivera / March 12, 2018

Dog skin cancer is perhaps one of the most common reasons pet owners may decide to visit their veterinarian. This is because a lot of dogs are at risk of developing canine skin cancer. From malignant tumors to mast cell tumors—in this article, we’ll briefly cover all you need to know about the various dog skin cancers that can affect your pet.

skin cancer in dogs

Dog Skin Cancer

Just like people, dogs and cats have the potential to develop cancers and tumors throughout their lives. Today, veterinarians estimate that 25% of dogs will at some point in their life develop a form of cancer. Additionally, research has suggested that 50% of dogs over the age of 10 are likely to die from cancer, thus suggesting that many older dogs are at risk of eventually developing some sort of canine cancer.

Types of Dog Skin Cancer

There are many types of dog skin cancers our canine friends can get. But, in this article, we will focus mainly on mast cell tumors, melanomas, squamous cell carcinomas, tumors of the skin glands and hair follicles, epitheliotropic lymphoma, and basal cell tumors.

To make this entire article much easier to understand, we’ll first define the various terminologies your veterinary oncologist may use when describing your dog’s skin cancer.

First, we need to understand what exactly is a tumor? Well, our body is made up of cells—and, when cells begin to replicate uncontrollably, then they clump up and form a mass. This is a tumor.

Benign and Malignant Tumors

Tumors can be classified as benign or malignant. A benign tumor is not cancerous and does not spread throughout the body. The act of cancer invading near-by tissue is referred to as metastasis. So, in contrast, a tumor that breaks off and spreads via the lymphatic system is referred to as a malignant tumor. This is cancerous and is a lot more difficult to treat.

Cancer can further be classed as a Carcinoma, Sarcoma, Leukemia, Melanoma, or Lymphoma. A carcinoma is a type of cancer that originates on the outer surface of the skin or more specifically, the epithelial layer of the skin.

Now, keep in mind that every organ also has an epithelial (outer layer) to it. Therefore, carcinomas can also occur on the outer surface of an organ. Examples of these types of dog skin cancer include squamous cell carcinoma and basal cell carcinomas.


A sarcoma is a cancer that originates within connective tissue such as fat or muscle. For example, hemangiosarcoma is a type of cancer that originates from the inner lining of blood vessels (not to be confused with Leukemia).


Leukemia is very different as it is a cancer of the blood. Blood contains a combination of red and white blood cells. When white blood cells replicate and grow continuously, they take over the red blood cell population.

Now, as we know, white blood cells are the body’s defense mechanism. Since these fast-growing white blood cells are not mature, they are not able to actually help the body in any way.  So, essentially, leukemia is the abnormal fast-growth and over-production of white blood cells in the body.

Melanomas and Lymphomas

Melanomas and lymphomas are pretty straightforward to understand! all we gotta do is break down the words. In Latin, the term -oma means “abnormal growth or tumor”. So, Melan– refers to melanin which is skin pigmentation. Therefore, melanoma denotes a cancer that originates on the melanin of the skin (melanocytes).

In contrast,  lymph- in physiology takes about that clear fluid our body produces in the lymph nodes. So, a lymphoma is cancer that affects our lymphatic system.

Mast Cell Tumor

mast cell tumors in dogs

Did you know an allergic reaction can also cause cancer? Mast cell tumors are a very common cancer that can be prevalent in breeds such as Boxers, Bulldogs, Pugs, and other brachycephalic (broad, short-skulled) breeds. Mast cells tumors are a type of blood cell cancer that occur as a result of the bodies response to an allergen.

A mast cell basically refers to a type of white blood cell that contains a lot of histamine molecules. Mastocytomas, more commonly known as Mast cells, can cause neo-plastic cancers like Mast Cell Sarcoma, and Mast Cell Leukemia.

Mast Cell Tumors and Your Dogs Lifespan

Mast cell tumors can be classified into three stages. The first stage implies that the mast cell tumor has not spread. Thus surgical removal will ensure that the skin tumor is completely eliminated.

Stage two, suggests that the skin tumor has spread deeper into the body. Dogs diagnosed with stage two mast cell tumor will require surgical removal of excessive tissue. You can estimate that a dog with this type of mast cell tumor can live for four years. Lastly, stage three mast cell tumors are the most serious.

Unfortunately, dogs diagnosed with stage three mast cell tumor will require radiation therapy and chemotherapy. Vets say that pets with stage three skin cancer may live anywhere from a few months to two years.

Melanoma in Dogs

Melanoma in dogs

Melanomas are a type of cancer that tends to affect pigmented (color-producing) cells known as melanocytes. So, you can expect to find canine melanomas in places such as their foot pads, around the mouth,  or in the mouth.

However, should a dog develop melanomas around their oral cavity or nail bed, this can be risky! The reason being, these kinds of melanomas can actually metastasize and invade internal tissues such the lymph nodes, liver, and other organs.

The general presentation of oral melanomas may include veterinary oncologists noticing the appearance of a swelling around the mouth region. Additionally, symptoms of oral melanomas include halitosis, an inability to consume food or water, an inability to hold food in the mouth, and loss of teeth.

Squamous Cell Carcinoma

Squamous cell carcinomas are a type of skin cancer that originates in the epidermal layer of cells. This just means that this type of cancer occurs mainly on the skin.

Studies show that large breed dogs are more at risk of developing squamous cell carcinomas, specifically Poodles, Labradors, and Samoyeds may be more at risk of developing squamous cell carcinoma.

Squamous cell carcinomas can also occur as a result of excessive sun exposure. So, it may be most prevalent in dogs with white skin, short hair, and white fur. Watch out for lumps on your dog’s belly as that’s where they generally form. This is because dogs tend to lie on their back, thus leaving their belly wide open for sunlight. So, make sure you limit your dog’s sun exposure and lather them up with plenty of sunscreen (yes, dogs can use sunscreen) that will protect your pooch from developing squamous cell carcinomas.

Tumors of the Skin Glands

If we were to look at our dog’s skin under a microscope, we’d see tiny, little glands. These are your sebaceous and sweat glands! Now, as their name suggests—the sebaceous gland secretes sebum (an oily secretion from your skin), and the sweat gland secretes sweat. So, these glands are also at risk of developing various types of cancers.

The veterinary name given to cancers that affect the sweat glands is Apocrine gland tumors. These types of cancers can further be classed as:

  • Apocrine adenomas
  • Apocrine ductal adenoma
  • Ceruminous adenoma
  • Ceruminous gland carcinomas
  • Apocrine carcinoma
  • Apocrine ductal carcinoma

Hair Follicle Tumors

There are a few types of tumors that can be associated with your dog’s hair follicles. These include:

  • Tricholemmomas: a benign type of tumor, found most commonly on a dog’s head. There is evidence to suggest that Poodles are at higher risk of developing tricholemmomas.
  • Trichofolliculomas: a type of hair follicle tumor, that is fortunately very rare.
  • Trichoepitheliomas: a type of follicular cancer that may be most commonly seen in dogs such as Basset Hounds, Irish Setters, Standard Poodles, and Golden Retrievers.

Epitheliotropic Lymphoma

Epitheliotropic Lymphoma is a rare form of neoplastic dog skin cancer that affects only 1% of the pet dog population. This type of cancer is a disease said to affect T-cells, and so it may often be referred to as Cutaneous Epitheliotropic T-cell Lymphoma.

The most common clinical signs of this type of canine cancer will include the presence of plaques, scaling, ulceration, mucosal lesions, and pruritus. As these cancer cells are rare, vets may often accidentally confuse these cancers with dermatits.

Dermatitis is a type of skin disease that occurs as a result of the allergic or non-allergic reaction. Symtoms of dermatits often include inflammation of the skin.

Basal Cell Cancer

Basal cell tumors are a type of canine cancer that’s commonly diagnosed in the Cocker Spaniels, Golden Retrievers, and Poodles. This type of tumor has the potential to either be malignant or benign.

Basal cell carcinomas are common in many dog breeds, but unfortunately not much is known about their cause. However, veterinarians believe that prolonged sun exposure has been linked to a higher risk of dogs developing basal cell carcinomas.

When veterinarians talk about basal cell tumors, this implies that the tumor is benign. However, if a veterinarian refers to cancer as “basal cell carcinoma”, then this indicates that the cancer is malignant.

Fortunately, your vet can treat basal cell cancers and basal cell tumors with cryosurgery or surgical removal.

Dog Skin Cancer Symptoms

The symptoms of canine skin cancer can be variable as each type of skin cancer will have different clinical presentations. Nevertheless, in general, your veterinarian will examine your dog’s skin for potential signs of cancer.

To start analyzing symptoms, veterinarians will take into account the age and the breed of your dog. For example, dog breeds such as the Norwegian elkhounds are at a high risk of developing prostate cancers.

However, in general, your veterinarian will look at the shape of the lumps present on your dog’s skin, the diameter of the lump or tumor, the color of the tumor, and any associated clinical signs such as ulceration.

What Does Skin Cancer Look Like

What your dog skin cancer will look like depends on what type of cancer they may have. But, often even veterinary oncologists may not be able to visually diagnose the type of cancer present in your pet. Thus, they will perform fine-needle aspirate (FNA) in order to view the architecture of your dog’s cancer cells more closely.

Fine needle aspirate means that your veterinarian will take a sample of the mass by inserting a needle into your dog’s lump. Your vet will then eject the contents onto a glass slide and view it under the microscope.

Melanomas will appear to have a dark brown, gray look to them. However, visually, they may be no more than 2.5 inches in diameter.

Mast cell tumors have a rubber-like appearance and ulcerations. Mast cell tumors are more common on the limbs and trunk of a dog.

Carcinomas, such as squamous cell carcinomas, will often look like a wart. These are the types of tumors that will be firm to the touch and can have a cauliflower-like shape.

Cancerous Moles

More common in senior dogs, moles can either be benign or malignant. Unfortunately, there are many types of cancerous moles an older dog can get. This includes melanomas, sebaceous adenomas, skin carcinomas, and mast cell tumors.

How To Tell If a Mole is Cancerous

Unless you’ve got an exceptionally trained eye and the skills of a veterinarian pathologist or oncologist—you will not be able to self-diagnose a cancerous mole on your pup!

Cancerous moles can, in general, appear black in color, and can be of any shape and size. But, only a trained eye and the proper diagnostic tools will be able to conclude whether or not your dog’s mole is malignant or benign.

Dog Skin Cancer Diagnosis

dog skin cancer diagnosis

There are a few diagnostic tools your veterinarian will use in order to diagnose the type of skin cancer a dog may have. These diagnostic methods include histology, cytology, FNA, and biopsy.

Histology and cytology is a diagnostic tool that allows veterinarians to view the tissue of the cancer cells. This will let veterinarians know the architecture of the cells and the type of cancer.

FNA (Fine-Needle Aspiration) determines if cancer is present and if so, what type it is. With this method, your vet may simply insert a needle into the mass or tumor growth. They will then eject the cancer cell contents onto a slide to view under the microscope.

Excisional biopsy simply means that the veterinarian will excise a small portion of the cancerous growth. This excised mass will then be placed in a solution of formalin until an oncologist or pathologist can examine it.

Treatment For Dog Skin Cancer

Traditional cancer treatments involve chemotherapy and radiotherapy, surgery, and histopathology.

Dog Skin Cancer Prevention

dog skin cancer prevention

Preventing canine cancer can be quite challenging—simply because the etiology of most cancers and tumors is still poorly understood.

As mentioned before, many dog breeds, such as Golden Retrievers, Poodles, and Scottish Terriers are predisposed to various types of skin cancers. The basis of this statement stems from the fact that cancers such as lymphomas or sarcomas can be genetically linked.

In fact, it’s worth noting that pedigree breeds will have a higher risk of developing some form of cancer during their lifetime. So, it stands to reason that the best method of dog skin cancer prevention is to not breed genetically prone or high-risk dogs.

 But, what should you do if you already have a high-risk breed?

First, know that you cannot manipulate nor control your dog’s genetics, but you can change their lifestyle in order to decrease their risk of cancer.

  1. You can potentially feed your dog a high-quality diet, that consists of fresh fruits, vegetables, and cooked meat!
  2. You can feed your dog foods rich in antioxidants, vitamins, and minerals. Foods such as fish oil, blueberries, kelp, turmeric, and pumpkin all have cancer-fighting properties.
  3. Spay and neuter your pets! Cancers such as mammary tumors, hemangiosarcoma, mast cell tumors, osteosarcoma, and prostate cancer are very common in unfixed dogs. Just make sure to not do it before 6 months of age.

5 Facts About Dog Skin Cancer

1.  Yunnan Baiyao is a type of Chinese herbal medicine that many people know for its wound healing properties. While it does not heal dog skin cancers, you can use it to stop or prevent bleeding from canine skin cancers such as hemangiosarcoma.

2. Radiation therapy is a painless method of treatment that vets use in order to treat skin cancers or tumors. The vet will administer a high dose of Radiation therapy so it will kill the cancer cells and prevent further replication.

3. If you have dogs and cats with allergies, watch out! The most common type of malignant cancer in our pets is mast cell tumors.

4. Hemangiosarcoma can spread to different organs. However, this type of canine cancer originates from the blood vessels in the body.

5. Mammary cancer is the equivalent to human breast cancer. Mainly affecting unspayed female dogs over the age of two years old, Mammary cancer has a 50/50 chance of either being a benign or malignant tumor.

Do you have a question about canine skin cancer? Let us know in the comments below!


How many types of dog skin cancer are there?

My dog has a mole. How do I know if it’s cancer?

How can I stop dog skin cancer before it starts?

Are all tumors cancerous?

What are the signs of skin cancer in dogs?


10 Foods That Help Fight Or Prevent Cancer In Dogs

Apocrine Gland Tumors

Mast Cell Tumors


About the author

Chelsea Hunt-Rivera

Chelsea Rivera is a Dedicated Pet Parent who loves to create amazing content for pet owners and is helping change pet wellness as the Head of Content for