Canine Skin Cancer

Skin cancer covers a wide range of tumors, that comprises any uncontrolled growth of cells of the skin and related structures like glands, hair follicles and supportive tissues (fat and connective tissue). Middle aged or older dogs are more vulnerable of getting affected by skin cancer, however, there are different types of canine skin cancers that may also occur in younger dogs. Studies show that skin cancer is found six times more in dogs as compared to cats, but is likely to be more benign than those in cats. Boxers, Scottish terriers, Bull mastiffs, Basset hounds, Weimaraners, Kerry blue terriers and Norwegian elkhounds are some of the common dog breeds that are at a high risk of having skin cancer.

Canine skin cancer can be either superficial (on or near the surface) or subcutaneous (under the skin) masses, hence, it becomes essential to differentiate the benign lesions from potentially malignant masses. Moreover, in dogs nearly 20 - 30% of skin cancers are malignant and usually some dermal masses having malignant potential are mistaken for benign lesions. This makes it even more important to get these skin masses evaluated by a veterinarian, as soon as they are observed. Benign tumors are usually slow growing, freely movable and non-painful, that mutate a bit over months and years. Whereas, malignant tumors are fast growing, have ill-defined margins, penetrative and ulcerative in nature.

Types and Causes
As per the cell type and cell division, the cancer can be divided into four categories:

• Epithelial Tumor: This tumor mainly affects the skin, glands in the skin or the hair follicles.
• Mesenchymal Tumor: The tumor develops from the cells that surround or support the skin like fat, connective tissue, blood vessels and nerves.
• Round Cell Tumor: Named after its appearance under microscope, the tumor include lymphosarcoma, mast cell tumors, histiocytomas, plasma cell tumors and transmissible venereal tumors.
• Melanoma: The tumor develops from melanocytes cells that provide pigment in the skin.

The causes are still unknown, however, excessive exposure to the sun, especially light colored dogs with thin hair coats may suffer two types of cancers: squamous cell carcinoma and hemangioma. Though rarely, sometimes genetic factors can also be the causes.

Symptoms
Systemic symptoms vary depending upon the site of the tumor and the extent to which it has developed and/or spread. However some of the common symptoms that can be seen in the dog are:

• Loss of appetite and anorexia
• Chewing or scratching the affected area
• Bloody vomit and diarrhea
• Abdominal pain
• Dark or black feces
• Itchiness and lethargy
• Irregular heart rhythm and blood pressure
• Enlarged lymph nodes
• Bleeding disorders and delayed wound healing

Diagnosis
Different diagnostic tests are required to be conducted, to detect the type of skin cancer and exclude other diseases. The veterinarian may take a fine-needle aspirate from the tumor to submit a sample for preliminary biopsy or cytology for microscopic examination of the cells. Urinalysis, X-rays, or ultrasound may be performed to determine how far the tumor has spread. Blood tests may comprise an entire blood count, serum chemistry profile, and buffy coat, that will reflect the low or high white blood cell count, low platelet count and raised cell counts.

Treatment
Treatment depends on the type of tumor and how early the disease has been diagnosed. However, if the tumor has not spread and is confined to a specific area, it can be removed through surgery without affecting the associated tissues. Chemotherapy or radiation therapy can be considered, if entire tumor cannot be removed surgically or if the tumor has spread to other tissues. For small and benign tumors, cryosurgery is conducted where the tumor and adjacent skin areas are frozen. Another advanced technique to cure canine skin cancer is photodynamic therapy, in which a dye is injected in to dog's blood stream that automatically localizes in the cancer cells. A laser of a specific wavelength is then used to excite the cells and kill them.

Hence, if you observe a new lump or sore on your pet's skin, that doesn't appear to heal, immediately seek veterinary attention as it can be a kind of canine skin cancer. Early diagnose, proper treatment and dog care will surely help to overcome this canine skin disorder.