Cancer in dogs: the warning signs
Not too long ago, when a dog owner learned that a dog had cancer, it meant a death sentence for the animal. But, thanks to advances in cancer research, things have changed.
Cancer is an uncontrolled growth of cells on or within the body. It may be localized, or it may invade adjacent tissues and spread throughout the body. Cancer is common in pet animals, and the rate increases with age. Dogs get cancer at roughly the same rate as humans, while cats get fewer cancers. Cancer accounts for almost half of the deaths of pets over 10 years of age.
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.
Cancer can occur in almost any location or body system – for example areas such as the skin, gastrointestinal tract (stomach, bowels), urinary system (kidney or bladder), blood, nervous system (brain tumors) and bones.
Different types of tumors can grow in each location of the cancer. A cellular diagnosis is needed to determine the "type" of cancer. For example, cancer of the skin can be due to basal cell tumors, mast cell tumors, lymphosarcoma and fibrosarcoma. Each tumor type within a location has a different treatment and prognosis.
Signs of Canine Cancer
Do you know the signs of cancer in dogs? Dogs get many of the same types of cancer as humans, and frequent physical exams and diagnostic tests help detect cancer before it is too late for treatment. Some common types of cancer in dogs are:
- 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.
If you notice any of the symptoms, consult with your veterinarian. 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.
What to Watch For
Signs of cancer in dogs may include:
- Any lump or mass that appears to be increasing in size;
- 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;
- Weight loss;
- Difficulty breathing;
- Persistent lameness or stiffness;
- Offensive odor;
- Difficulty eating or swallowing.