Dogs and Skin Cancer
You might not give much thought to dog skin cancer, because your loyal companion is covered with hair and protected from the sun. But you should know that skin tumors, which may be cancerous, are the most common tumors found in dogs. Fortunately, when caught early, many cases of dog skin cancer can be treated successfully.
Not all varieties of dog skin cancer are caused by sun exposure, but sun damage to the skin can be a causative factor. All dogs have certain areas, such as the nose and the pads of the feet, where there is no hair to shield sensitive skin from the sun. Additionally, pooches with light-colored or thin coats are more susceptible to sun damage over their entire bodies.
Because some types of dog skin cancer, including dog melanomas and mast cell tumors, are fatal if untreated, it is important that you have your veterinarian check any suspicious growths.
Types of Skin Cancer in Dogs
There are different types of dog skin cancers. Three of the most common include:
Malignant melanoma. Just as in people, malignant melanoma is a type of skin cancer in dogs that affects pigmented cells known as melanocytes. Dogs often develop benign tumors in pigmented cells that do not metastasize, which are called melanocytomas. These tumors are found on areas of the dog's body that have hair.
Most malignant melanomas occur on the mouth or mucous membranes, although about 10% of the time they are found on parts of the body covered with hair. They tend to grow extremely fast and are likely to spread to other organs, including the lungs and liver.
No one knows exactly why melanomas develop, although genetic factors seem to play a role. Additionally, trauma or compulsive licking of a particular spot on the skin may increase the likelihood that cells will multiply, thereby raising the chances that cells will mutate during the division process and become cancerous.
Squamous cell carcinoma. This form of dog skin cancer, which occurs in the epidermis, is often caused by exposure to the sun. Scientists believe there may also be a connection between the papilloma virus and the development of squamous cell tumors in certain dogs.
Although squamous cell cancers do not spread to surrounding lymph nodes, they are aggressive and may lead to destruction of much of the tissue around the tumor.
Mast cell tumors. These dog skin cancers, which occur in the mast cells of the immune system, are the most common skin tumors in canines. Veterinarians don't know what causes mast cell tumors to develop, although there have been cases where they have been linked to inflammation or irritants on the skin. Evidence suggests genetic factors are often important, and the hormones estrogen and progesterone may also affect cancer growth.