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Melanoma in Dogs

A black and tan dog walks down a road in a forest

It may be surprising to learn that many of the cancers that affect humans can also affect their dogs. They can develop tumors internally or can develop them on their skin and in their mouths. Melanoma is one such cancer, and it can occur on the skin or inside of your dog’s mouth. While the skin version of melanoma can be relatively benign, the oral form is much more severe.

What is Melanoma in dogs?

Cells calledmelanocytesare responsible for producing pigment that colors the skin. If your dog has black pigment anywhere on his skin or in and around his mouth, this is because of the pigment that comes from melanocytes.

Diseased melanocytes grow in an unchecked manner, forming a tumor. A combination of hereditary and environmental factors can cause melanocytes to do this. For example, sunlight exposure can increase the risk of developing melanoma of the skin. Certain breeds like Cocker Spaniels, Chow Chows, Golden Retrievers, Schnauzers, and Miniature Poodles have a higher risk of developing melanomas.

Oral melanoma is the most common type of malignant tumor that can develop in your dog’s mouth. It can appear pigmented or can have a non-pigmented appearance known asamelanotic melanoma. What makes it so malignant is that it can invade underlying bone and spread to other parts of the body, causing facial swelling and eventually making it difficult and painful for your dog to eat.


If your dog will let you brush his teeth, this is the best time to look at his mouth and around his gums. Sometimes, an oral tumor may appear as a small amount of extra tissue, or it may appear as a perfectly round tumor coming from the gingiva or on the inside of the lips and cheeks. Tumors can also form on the roof of the mouth or under the tongue. If you see a new lump or bump, bring it to your vet’s attention as soon as you can. Oral pain or bleeding from the mouth is a more urgent sign and may warrant a trip to the emergency room.

A fine needle aspirate can be performed on any number of skin bumps. This involves the use of a needle and syringe to collect cell samples from the bump. Sedation is usually necessary since the mouth is a sensitive place, but sometimes fine needle aspirate results are inconclusive. This is especially true for bumps that are too firm and don’t give up cells very easily. In this case, general anesthesia and biopsy are necessary for a definitive diagnosis.


Biopsies can sometimes remove all the visible tumor, but with melanoma, there is a high likelihood that there is some microscopic disease left behind. Definitive treatment will require additional surgery to remove the underlying disease, and specialized imaging like CT scans will be necessary to determine the extent of the tumor. If the tumor is invading bone, then surgical margins will need to include bone. This would be a highly invasive surgery which may mean that your dog could lose part of his face or jaw.

For tumors that are inoperable, radiation therapy can help with treatment, especially with very small melanomas. There is also a vaccine known as Oncept which helps with the microscopic disease, though it cannot prevent melanoma completely nor can it preventmetastasis or spread of cancer.

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Dogs who go through surgery may need an Elizabethan collar or cone to prevent scratching around their faces. Soft food or liquid diet is recommended for at least two weeks while the mouth heals. Dogs who need radiation therapy may appear lethargic or have some nausea, but if the radiation is focused only on your dog’s mouth, then he may be less likely to experience these problems.

Your pup will also need frequent follow-ups with his veterinarian. It may also be necessary to repeat a CT scan later to make sure that cancer does not return.

If you choose to not pursue surgery and radiation therapy, your dog will eventually stop eating. This is usually because the tumor is preventing him from eating comfortably due to the invasion of the surrounding bone. This may occur anywhere from three to six months after the initial diagnosis, but it is possible for this timeline to be shorter or longer in certain cases.

Melanoma is one of the most malignant oral tumors in dogs. It can cause facial swelling and painful eating without treatment. Early diagnosis is best because surgery will be more effective if there are only small surgical margins compared with larger, more aggressive melanomas. Surgery and radiation are the treatments of choice, and the Concept vaccine can help with the microscopic disease.

Meet The Author 

Dr. Erica Irish DVM


Erica has worked in the veterinary field since 2006, starting out as a veterinary technician before graduating from the UF College of Veterinary Medicine in 2013. As a general practitioner in an animal hospital, she has many interests and is especially interested in dermatology, cardiology, internal and integrative medicine.

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