An Interview with Veterinarian Ann E. Hohenhaus, DVM
Did you know that, despite all their fur, dogs can develop skin cancers? Sun & Skin News discussed canine skin cancer prevention and treatment with Ann E. Hohenhaus, DVM. A Diplomate of the American College of Veterinary Internal Medicine and certified in both Oncology and Small Animal Internal Medicine, Dr. Hohenhaus practices at The Animal Medical Center in New York City (www.amcny.org).
Q. What kind of skin cancers do dogs most commonly develop?
A. Mast cell skin cancer is the most common skin cancer in dogs. Mast cells are allergy cells, and swelling, itching, and redness are commonly associated with these tumors. Sun exposure is not believed to play a part, because these cancers can develop anywhere on the body, even areas well covered by hair. When dogs develop these raised, hairless, raspberry-like skin tumors, we surgically remove them. Since some mast cell tumors spread, a biopsy of the tumor tissue is taken for examination in the lab, to confirm the diagnosis and determine whether chemotherapy and/or other treatment is appropriate.
Q. What about the two most common cancers, basal and squamous cell carcinoma?
A. In humans, the two most common skin cancers are basal and squamous cell carcinoma (BCC and SCC). BCCs in dogs are rare, and most are simply removed surgically. SCCs in dogs, however, while also rare, are more likely to require treatment beyond surgery, such as radiation or chemotherapy. Light-haired dogs are more likely to develop sun-induced SCCs, which tend to appear on sparsely haired areas, such as the belly.
Q. Can dogs also develop melanoma?
A. Melanoma is more common than BCCs and SCCs in dogs, and its location determines its severity. Melanomas of the haired skin (trunk and limbs) are usually noninvasive, and can be easily removed surgically. Melanomas on the toe or in the mouth are highly invasive, spread easily, and may be fatal. Unlike SCCs, however, melanomas are more common in dark-haired dogs, like black labs and cocker spaniels; heredity is believed to play a role in their development. Hereditary factors may also lead some dogs to develop ocular melanomas. Pedigree analysis of golden retrievers and Labrador retrievers revealed a form of ocular melanoma which is believed to arise in part from one or more genetic mutations. Treatment is usually removal of the eye.
Q. What can I do to protect my dog against these cancers?
A. Providing shade can help prevent suninduced skin cancers. If your pup spends much time outdoors in a gated play area, for instance, have it fitted with a sunroof. Sun-protective clothes, goggles, and even sunscreen are available at many pet supply stores. Most dogs should tolerate sunscreen on the nose and ears. With melanoma, early intervention is important. Teach your dog early on to let you open its mouth, so that you can periodically look inside for anything unusual. Stinky breath could be a clue to a mouth tumor, so make sure your dog receives routine vet care, including dental exams. Identification of these melanoma early warning signs should help catch the cancer at an early stage. Melanoma and SCC on the toe are often associated with a broken toenail, so if your dog keeps licking a toe with a broken toenail, or the nail doesn’t grow back right, have it checked out. When tumors are caught and treated early, dogs usually survive.