Malignant Melanomas in Dogs

French bulldog

Melanomas, or tumors arising from pigment producing cells, are more often than not benign in dogs, especially when they occur in the skin. Unfortunately, this is not true for melanomas that occur in the mouth or on the toes/nail beds. In those locations on dogs, melanomas tend to be malignant and are prone to destructive growth locally and re-growth even after surgery as well as to metastasis or spread to other locations in the body.

What will you see if your dog has a malignant melanoma?
Whether on you or on your dog, you should always try to be aware of any new growths that occur. As is often the case, you just cannot always tell by looking whether a lump is benign or malignant. In addition, even though melanomas are derived from pigment producing cells, they can occur in an un-pigmented form (called amelanomtic) where they are a normal-looking, healthy pink color. So pigmented or not, you should always have your veterinarian check any new growths your dog develops.

Of course, you may actually find the tumors because of clinical symptoms associated with their location on your dog. For instance, toenail tumors may cause a swollen toe, a deformed nail, licking at the site or even lameness. Likewise, tumors in the mouth may bleed, causing drooling or bad breath, or difficultly eating and swallowing.

How do you know for sure your dog has a malignant melanoma?
Your veterinarian will have to send a tissue sample to the laboratory in order to get a definitive diagnosis either by a needle aspirate or surgical biopsy.  If the diagnosis is malignant melanoma your veterinarian will want to run other tests (blood work, X-Rays, ultrasounds, aspirates) to establish your dog’s general overall health (to make sure he doesn’t have any other illnesses) and to stage the cancer (establish as best as possible if it exists in any other locations). This information is important in order to give you a clearer picture of your dog’s individual condition and prognosis.

What can you do if your dog has a malignant melanoma?
Sadly, malignant melanomas are very aggressive cancers. The prognosis is guarded, and the odds of long term survival are not good. Complete surgical removal of the original tumor is always the best first step provided that the size and location of the tumor allow for it. Unfortunately that is not always the case.  Radiation therapy may be indicated in some instances for non-surgical tumor control or even after surgery where excision of the cancer was not complete. Chemotherapy may also be an option. And there is even a vaccine that is approved for the treatment of microscopic malignant melanomas in dogs.

Once your veterinarian has gathered all available information, he can then counsel you on the best approach for treating your dog and whether you will need to be referred to a veterinary oncologist or cancer specialist. Just remember that treating cancer is not something you do expecting to cure the condition, but rather to control it and to slow down the progression. That is why it is particularly important that you make sure that you fully understand what your veterinarian is telling you regarding your dog’s prognosis, the treatment plan being proposed and what reasonable expectations you should have for achieving happy, quality time with and for your dog before moving forward.

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.


Reviewed on: 
Tuesday, February 3, 2015