Dogs with dark coats are more at risk for squamous cell carcinoma than other dogs. It is not yet known why, but it may have something to do with the way dark colors tend to absorb sunlight rather than reflect it. Exposure to sunlight is considered a major risk factor for squamous cell carcinoma.
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What It Is
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Squamous cell carcinoma is an aggressive form of cancer that destroys a wide margin of surrounding tissue, although it does not spread to the lymph nodes.
Where It Occurs
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Lesions will appear wart-like or ulcerated, and can occur on any part of the dog’s body. Dark-colored dogs are known to be more at risk for the subungual variety, which occurs under the toenails.
Diagnosis
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Diagnosis is made through a combination of examination and biopsy. A fine-needle aspirate may be performed instead if the lesion is subungual. Unlike a biopsy, where an actual chunk of tissue is removed for study, a fine-needle aspirate involves the insertion of a hypodermic needle into the mass. When it is pulled out, it contains a tiny sample of the cells as well as a sample of any fluid that may be present.
Treatment
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Tumors must be removed surgically, and most dogs with subungual lesions require amputation of the affected toe. Chemotherapy and radiation may be used as palliative care.
Prognosis
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Dogs who undergo removal surgery have a 95 percent one-year survival rate, and chemotherapy and radiation can extend that time span.
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