Cancer is the word used to describe any malignant tumor. Malignant means that the tumor is capable of spreading and invading other tissues. Cancer occurs when cells grow uncontrollably on or inside the body. The risk of cancer increases with age, and common cancers seen in dogs include mammary (breast) tumors, skin tumors, testicular tumors (in unneutered males), mouth cancer, and lymphoma. Be concerned about cancer if your dog shows any of the following signs:
Lumps that don't go away or that grow larger
Sores that don't heal
Unusual or excessive weight loss
Lack of appetite for more than a day or two
Bleeding or discharge from any body opening
Difficulty eating or swallowing
Unexplained lack of energy
Cancer is generally diagnosed with a biopsy the removal and study of a section of tissue. Other diagnostic techniques your veterinarian may use are blood work and X rays.
Mammary tumors are the most common type of cancer in female dogs and are most often seen in older unspayed females. The tumors can be removed surgically and your dog may also benefit from chemotherapy afterward. The best way to prevent or greatly reduce the risk of mammary cancer is to spay a female before her first heat cycle.
It's not unusual for older dogs to develop lumps and bumps on or beneath their skin. Generally these growths are harmless, but it's a good idea to have your veterinarian take a look at them to be sure. Always take your dog in for a checkup if a growth becomes larger or changes color.
Harmless but unsightly growths such as cysts, papillomas (warts), adenomas, and lipomas can be removed surgically. You might also want to do this if a growth is impeding your dog's movement.
Mast cell tumors are a common type of malignant skin cancer. They can develop anywhere on or in the body and resemble raised, nodular masses. Mast cell tumors may feel solid or soft when touched. Most commonly, they develop in dogs that are eight to ten years old, although they can occur at any age. The best treatment is surgical removal, sometimes followed by radiation therapy to kill any remaining tumor cells. In advanced stages of the disease, chemotherapy may be helpful.
Testicular tumors usually develop in male dogs that are at least ten years old, but they have occurred in dogs as young as three. Dogs with retained testicles (which remain up inside the body) are most likely to develop testicular cancer. Testicular cancer is treated surgically, followed by chemotherapy or radiation if the tumor has spread. Neutered dogs do not get testicular cancer.
The most common mouth (oral) cancer in dogs is malignant melanoma. One out of every twenty canine cancer diagnoses is for this disease. Malignant melanoma is highly aggressive, so catching it early is important. That's just one of the many good reasons for brushing your dog's teeth on a regular basis — you're more likely to spot the signs of this disease, which include a mass on the gums, bleeding gums, bad breath, or difficulty eating.
Will my dog lose his hair and become nauseous if he has chemotherapy?
Luckily for dogs, they don't suffer the same side effects from chemotherapy that people do. You may notice, however, that he's tired for a few days after each treatment.
Oral cancers are diagnosed using biopsies and X rays. They're treated surgically and may require a follow-up treatment of radiation therapy. A potential new approach to treating malignant melanoma is a DNA-based vaccine that's being studied at New York City's Animal Medical Center.
If your dog has an unusual swelling or enlargement in the lower neck area, he may have lymphoma, a tumor of the blood-forming system. An examination by your veterinarian may show that all the body's lymph nodes are enlarged. Blood work, a biopsy, and chest and abdominal X rays may all be necessary to confirm the diagnosis and determine where the tumor is located and how large it is. Lymphoma usually responds well to chemotherapy.