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Malignant Melanomas in Dogs

Posted February 03, 2015 in Dog Diseases & Conditions A-Z

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.

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Mike has more than 35 years of experience in companion animal veterinary practice and is a valued member of IDEXX’s Pet Health Network team since 2013.