Canine Cancer - The Signs of Possible Cancer in Your Dog

Dogs commonly get cancer. Cancer accounts for almost half of the deaths of pets over 10 years of age. It is a disease that is characterized by a group of cells that grow to invade and destroy adjacent tissues. Cancer (neoplasia) is a transformation of normal cells into abnormal malignant cells, and it can take many forms. Some involve solid masses, or tumors, while others involve the blood or bone marrow in leukemia. It may also spread to distant areas through a process called metastasis.  Cancer can develop in virtually any organ or body system.

Cancer can occur in the skin, under the skin and affect just about any location or organ in the body. There are also several types of cancer that is possible at each location. The signs of cancer vary with the location and type of cancer. The aggressiveness of the cancer will depend on the type of cancer, the location and the individual pet.

Because cancer can affect almost any organ or body system, the signs can be just about anything. For example, if the cancer involves a bone, some animals will be lame. If the cancer involves the skin, you may feel a mass. If the cancer involves the intestine, some pets will exhibit signs related to the intestinal tract such as not wanting to eat, loosing weight, vomiting, diarrhea or abdominal pain.

Types of canine cancer:

  • Skin tumors. Skin tumors in dogs are rather common. Melanomas, lipomas, basal cell tumors and mast cell tumors are the most often diagnosed. All skin tumors – lumps or masses of any sort – should be examined by your veterinarian.

  • Lymphoma. This form of cancer is common in dogs. Lymphoma can affect the digestive system, resulting in lethargy, vomiting and diarrhea. It can also affect the liver resulting in lethargy, vomiting and a yellow tinge to the gums and skin. Lymphoma can also affect the chest, causing coughing and difficulty breathing.

  • Mammary gland tumors. These tumors are more common in the older female dog that has not been spayed. About 50 percent of all tumors in dogs are mammary gland tumors. Of those, about ½ are malignant. Typically, a lump is felt in the breast tissue. Although they are most common in intact dogs, they can also occur in spayed dogs.

  • Abdominal tumors. Abdominal tumors are common, but it is difficult to make an early diagnosis. Some examples include hemangiosarcoma, mast cell tumors, lymphoma and prostate cancer. You should be aware of any weight loss, weakness, pale gums, protracted vomiting, continual diarrhea, and/or abdominal enlargement and see your veterinarian if these signs occur.

  • Testicular tumors. This type of tumor is the second most common tumor of intact male dogs. Signs are usually one large testicle and one normal sized testicle. If malignant, the cancer can spread throughout the body, resulting in weakness, lack of appetite and weight loss.

Some common warning signs of cancer may include:

  • Any lump or mass that appears to be increasing in size

  • A firm mass

  • A mass that seems attached to the underlying tissue

  • A pigmented mass

  • A mass that changes its character

  • Weight loss

  • Repeated vomiting – especially in an older dog

  • Coughing

  • Bloody urine

  • Any sore that does not heal

  • Change in bowel or bladder habits

  • Difficulty urinating or defecating

  • Unexplained bleeding or discharge from any body opening

  • Loss of appetite or difficulty eating or swallowing

  • Difficulty breathing

  • Persistent lameness or stiffness

  • Offensive odor

Is there any hope for a cure?

Not too long ago, when a dog owner learned that a pet had cancer, it meant a death sentence for the animal. But, thanks to advances in cancer research, things have changed. If found early, most of these cancers can be cured with surgery, chemotherapy, radiation therapy, or a combination of the three, and early diagnosis will aid your veterinarian in delivering the best care possible.

Unfortunately, the cause of most cancers is not known and therefore prevention is difficult. One type of cancer, breast cancer, is largely preventable with early spaying. Fifty percent of all breast tumors in dogs are malignant. Spaying your pet prior to the first heat cycle will greatly reduce the risk of breast cancer.