Canine Skin Cancer

Common Canine Skin Tumors

• Lipomas: These are fatty tumors and are the most common soft skin tumors in dogs. They are soft since they are basically fat. However, some malignant tumors such as mast cell tumors resemble fatty tumors so even if you suspect a lipoma on your dog, it is important to have your vet confirm it by fine needle aspiration. Usually, lipomas can be left alone and need only be removed surgically if the location and size of the tumor is causing a problem to the comfort or mobility of the dog.
• Melanomas: Melanomas are also common skin tumors in dogs and account for about 5 to 7% of all canine skin tumors. Many melanomas that occur on the skin of dogs are benign. The tumors are usually darkly pigmented and appear as black tumors on the skin, from one-quarter to 2 inches in diameter. They occur most often on the head, digits or back. Melanomas are more common in older dogs (the average age is nine years).
• Papillomas: Papillomas are commonly known as warts. They are firm and smaller than lipomas and are cauliflower-like growths. A dog can have one or multiple papillomas. (Puppies usually have multiple growths whereas older dogs commonly have a single growth). In puppies (not older dogs), these tumors are mostly viral in nature and usually disappear in a few months as the puppy's immune system strengthens. They can occur on the head, eyelids, feet, and in and around the mouth. Papillomas can be confirmed by fine-needle aspiration, and can be removed either by surgery, electrocautery (using electric current to remove the tissue), or cryosurgery (freezing the tissue).
• Sebaceous Adenoma/Hyperplasia: Sebaceous hyperplasia is rather common in dogs. This type of tumor may be solitary or multiple wart-like growths that are pinkish in color and are small (less than 1 cm in diameter). These tumors occur more commonly in older dogs and often appear on the eyelids, other areas of the head, trunk and feet. Breed-wise, Miniature Schnauzers, Beagles, Poodles and Cocker Spaniels are more susceptible. Sebaceous hyperplasia can be confirmed by fine-needle aspiration and removed by surgery.
• Histiocytomas: Histiocytomas are common benign skin tumors in dogs as well. They commonly occur in younger dogs (under 3 years of age). Certain breeds are predisposed, such as Cocker Spaniels, Doberman Pinschers, Boxers, Labrador Retrievers and Scottish Terriers. These tumors are usually solitary but fast growing. They are dome-shaped with a hairless or ulcerated surface. Solitary histiocytomas may spontaneously regress (disappear) in approximately 3 months. They can be treated by surgical removal.
• Basal Cell Tumors: Basal cell tumors are benign tumors that occur in the deepest layers of the skin. They are usually solitary, well-defined, firm, and freely movable. These tumors are usually found on the head, neck, and shoulders. Older dogs and Poodles are more susceptible to this tumor. Surgical removal is the conventional treatment.

• Mast Cell Tumors: Mast cell tumors are the most common fatal canine skin cancer, accounting for 16 to 21% of all skin tumors in dogs. These tumors arise from tissue mast cells. The average age at diagnosis is 8 years. Mast cell tumors are commonly known as the "Great Imitators" because they resemble fatty tumors (lipomas) and other benign lesions. As such, these dangerous tumors are often not diagnosed until later in the disease, making treatment more difficult and prognosis less favorable.
• Squamous Cell Carcinoma: Squamous cell carcinoma (SCC) is the most frequently diagnosed carcinomas arising in the skin in dogs. They usually occur on non-pigmented and hairless sections of the skin and is commonly seen as a result of sun damage. This canine skin cancer is locally aggressive but rarely metastasize until later in the course of the disease.
  There are two forms of SCC - cutaneous SCC and subungual SCC.
  Most cutaneous SCCs are firm, raised ulcerated nodules. Older dogs are more susceptible. Breed-wise, Bloodhounds, Basset Hounds, and Standard Poodles are predisposed.
  Subungual SCCs occur in dogs with a dark haircoat, and are most commonly found in Schnauzers, Briards, Kerry Blue Terriers, and Standard Poodles. Females have a slightly higher rate of occurrence than males.
  Surgical removal is the treatment of choice. Where surgery is incomplete or not possible, radiation can be used. Limiting exposure to the sun may help prevent sun-induced squamous cell carcinomas.
• Hemangiosarcoma: Hemangiosarcoma is a soft tissue tumor (sarcoma) that arises out of blood vessels. It commonly arises from the spleen, the liver, and the skin.
  There are two forms of hemangiosarcoma of the skin - dermal or subcutaneous.
  The dermal form is associated with sun exposure and tends to occur on hairless or sparsely-haired skin (e.g. inner thigh, abdomen). Dermal hemangiosarcoma looks like a red or black growth on the skin.
  Dogs with short white haired fur (such as dalmatians, whippets, and pit bull terriers) are predisposed.
  Subcutaneous (under the skin) hemangiosarcoma can occur anywhere on the body. The tumors can be soft and movable, or they can be firm and infiltrative. Surgical removal is the treatment of choice but sometimes complete surgical removal can be difficult, in which case radiation and/or chemotherapy can be used.
• Fibrosarcoma: Firbosarcoma is a type of soft tissue tumor that arises from fibrous connective tissues. These tumors are often subcutaneous (under the skin) but can grow and extend through the skin resulting in ulceration of the overlying skin. They are locally invasive but less likely to metastasize to other parts of the body. Tumors can be solitary or multi-nodular and often will have obvious attachments to the surrounding normal tissues. In dogs, fibrosarcomas are most common on the trunk and extremities.
  This canine skin cancer occurs more frequently in older male dogs.
  Treatment options include aggressive surgical removal, or a combination of surgery and radiation, and with or without chemotherapy.

Causes of Canine Skin Cancer

Symptoms of Canine Skin Cancer

• Appetite loss
• Weight loss
• Weakness and lethargy
• Vomiting (maybe bloody)
• Diarrhea
• Coughing
• Wounds that cannot heal
• Enlarged lymph nodes

Diagnosis of Canine Skin Cancer

• Blood tests
• Biochemistry profile
• Urinalysis
• Chest and abdominal X-rays
• Ultrasound
• Lymph node aspirate
• Bone marrow aspirate

Conventional Treatment of Canine Skin Cancer