Melanoma in Dogs: Common Symptoms, Causes, and Treatment

Melanoma is a cancerous tumor that comes from pigmented cells called melanocytes.

Melanocytes are specialized cells at the deepest part of the epidermis (outer layer of skin) that make melanin, the pigment that gives a dog color in its skin, hair, and eyes. 

What Is Melanoma in Dogs?

Melanoma shows up most often as a dark-colored mass, but it can also be pink. The mass may bleed or break open as it grows.  

Melanoma can be aggressive and quickly spread to other parts of the body. This condition is a medical emergency and, if you notice it, your dog should be seen by a veterinarian right away. 

Types of Melanomas in Dogs  

Melanoma is generally categorized by location. It can grow anywhere on the body, but three types of melanomas in dogs are seen most often. 

• Oral melanoma—This is the most common type of melanoma in dogs and accounts for up to 35.8% of all cancerous tumors found in the mouth. It is typically very aggressive and likely to metastasize (spread) to the lymph nodes and lungs. 

• Digital melanoma—This occurs when melanoma appears in the dog’s nail bed or between their toes. It can be aggressive and spread to other areas of the body. 

• Ocular melanoma—This type of melanoma commonly affects the eyelids, conjunctiva (the protective layer covering the inner surface of the eyelid and front of the eye), and uvea. the middle layer of the eye. Ocular melanoma typically does not spread. 

Symptoms of Melanoma in Dogs

Oral melanoma symptoms include: 

• Bad breath 

• Drooling 

• Abnormal saliva consistency (thickness) 

• Visible mass in the mouth 

• Lack of interest in eating 

• Weight loss 

Digital melanoma symptoms include: 

• A loose toenail 

• An irregularly shaped toenail 

• Limping 

• Paw licking 

Ocular melanoma symptoms include: 

• Vision loss 

• Changes in eye shape or color 

• Eye bulging 

Causes of Melanoma in Dogs

There is no known singular cause of melanoma. Rather, several genetic and environmental factors likely play a role. 

As is the case with most cancers, older dogs are more likely to get melanoma than younger dogs. Anecdotal evidence also suggests that males are more likely than females to be diagnosed with melanoma, as are certain breeds.  

For example, one study of 338 dogs with oral melanoma found Golden Retrievers, Pekingese/Poodle mixes, and Chow Chows to be overrepresented.

Another study found that Rottweilers and Labrador Retrievers were at higher risk for digital melanoma than others. However, some sources state that there is no fully confirmed breed predisposition. 

Unlike in humans, exposure to ultraviolet (UV) light is not considered a big risk factor for melanoma in dogs. 

How Veterinarians Diagnose Melanoma in Dogs

Your dog’s veterinarian will start with a full physical exam, followed by a series of tests based on your dog’s symptoms, needs, and past medical history. 

• Blood work—Checking a dog’s complete blood cell count (CBC) or blood chemistry profile can give information on their overall health and any abnormalities that show a new or ongoing medical issue. 

• Urinalysis— Checking the dog’s urine can help show kidney, liver, and urinary system health. 

• Imaging—Several imaging techniques are available, including X-ray, a CT scan, and ultrasound. More than one method may be used depending on the location, evidence that the cancer may have spread, or inconclusive results. 

• Biopsy—Taking a sample of the tumor itself can be done several ways. A fine needle aspiration (FNA) involves taking out some cells of the suspicious mass to be looked at under a microscope.

  • An incisional biopsy involves cutting a piece of the tumor tissue for examination, while an excisional biopsy involves removing the entire tumor to be checked. Your vet may opt to biopsy other parts of your dog’s body, such as the lymph nodes, to help figure out if the cancer has spread. 

Before your dog’s visit with their vet, it's a good idea to make sure that your dog’s medical records are up to date and include their entire medical history.  

A list of symptoms with timelines can also be handy to make sure you’ve shared all the information with your dog’s veterinarian. 

Treatment of Melanoma in Dogs

Left untreated, melanomas will continue to grow.  

The course of treatment chosen will depend on the characteristics of your dog’s melanoma, as well as their age and general health.

Dogs diagnosed with advanced stage melanoma may not be treated and may have a more guarded prognosis (or poor probable outcome) based on the factors examined.

Unfortunately, if the prognosis is poor or quality of life suffers, humane euthanasia may be recommended by your vet.  

Surgery is typically the preferred treatment option. In the case of oral melanoma, the mass is usually removed in full or part. Partial removal of the upper or lower jawbone may be needed to ensure the mass is fully taken out.  

The treatment of digital melanoma may be full surgical removal of the toe, and the treatment of ocular melanoma may involve the partial or complete removal of the eye. 

Secondary (adjuvant) treatments may also be recommended in addition to surgery. These include radiation; chemotherapy drugs such as toceranib, prednisone, and lomustine; cryotherapy; photodynamic therapy; laser therapy; and the canine melanoma vaccine.  

The melanoma vaccine works by stimulating the dog’s body to make antibodies that fight melanoma cancer cells.

The vaccine is typically given once every two to four weeks, then every six months thereafter. It’s given for the treatment of oral melanoma but often is under the purview of a veterinary oncologist. 

Recovery and Management of Melanoma in Dogs

Recovery time from surgery depends on a variety of factors. Dogs with simple cases will likely recover in about two weeks. Others can take more than two months.  

Your dog will be sent home with pain management medication to help keep them comfortable.  

You’ll want to limit their activity, check their surgery site daily for any signs of infection (such as redness and swelling), and keep them in a quiet, confined space to give them time to heal. 

Many products can aid your dog in their recovery process: 

• Prescribed pain medications, such as gabapentin 

• A white noise machine for dogs  

• Recovery cone  

• Orthopedic dog bed 

• Dog gate 

Your dog’s veterinarian will schedule a series of follow-up appointments to continue checking your dog’s status.  

Prevention of Melanoma in Dogs

Melanoma does not have a singular known cause, making preventative measures hard to determine.  

The prognosis of a dog diagnosed with melanoma will improve very much if caught early, so regular veterinary checkups are very important. 

 Any suspected signs of melanoma are worth a veterinary exam and should be taken seriously.