Cancer in dogs

Overview

Recently you noticed an unusual growth on your dog's tummy. When your veterinarian explains that it is a tumor, you feel a shiver go down your spine. Could your beloved pet have cancer?

Cancer is marked by an abnormal growth of cells that is uaually noticed once it has developed into a mass of tissue known as a tumor. It can affect just about any part or system of a dog's body.  A tumor that spreads into surrounding organs and structures is said to be malignant.  Malignant tumors are typically harder to treat and may require surgical removal, chemotherapy, radiation, or some other form of treatment . 

However, not all tumors are serious threats to your pet's health. Those that do not spread to surrounding tissue are called benign tumors. These kinds of tumors are sometimes removed by a veterinarian, as they can still do damage if they rupture, hemorrhage, or place pressure on nearby tissues or organs.

Symptoms

Symptoms of cancer vary according to the type of cancer, and there are many. Some dogs do not exhibit any symptoms at all in the earliest stages. Any of these symptoms might indicate cancer:

• Difficulty eating or swallowing
• Extremely bad breath
• Rapid or labored breathing
• Abnormal lump or bump, especially if it gets larger
• Open sore that doesn't heal
• Difficulty urinating or defecating
• Loss of appetite, weight loss
• Bloody discharge
• Lameness, stiffness
• Weight loss
• Poor haircoat
• Change in behavior
• Seizures

Causes & prevention

Cancer does not appear to have a single cause, but rather is triggered by a multitude of factors, including genetic, environmental, nutritional, and traumatic. It usually appears in middle-aged to older animals. Some breeds, like Golden Retrievers, are known to have a higher incidence of cancer. Female dogs spayed before they reach sexual maturity at 6 to 9 months have much less risk than an intact female of developing mammary cancer. Neutering prevents testicular cancer in males and greatly reduces the likelihood of prostatic cancer.

Treatment

Your veterinarian may use x-rays, ultrasound, blood tests ,or perform a biopsy to determine the nature of your pet's illness. There are many options for the treatment and cure of cancer, including surgery, chemotherapy, and radiation therapy, depending on the type of cancer diagnosed. Most tumors are removed surgically, and checked to be sure the malignant cells on the outer margins of the tumor were completely removed. Make treatment decisions based on the prognosis for the dog's recovery, age and overall health. A vaccine is now available to assist in the treatment of canine malignant melanoma, a tumor that most often affects the tissues of the mouth.

The future

If your dog is diagnosed with cancer, it's not necessarily a death sentence for your pet. Many animals recover completely. If the cancer cannot be cured, he may still be able to live comfortably for a long time. Work with your veterinarian to monitor your pet's health, so any recurrence is caught early.

Resources

Common signs of Cancer, http://www.zzcat.com/index.htm#signs

Golden Retriever Foundation Leads Fight against Canine Cancer, http://www.goldenretrieverfoundation.org/research.html

DNA-Based Vaccine Triples Survival for Dogs with Melanoma http://www.mskcc.org/mskcc/html/13199.cfm, Memorial Sloan-Kettering Cancer Center, April, 2003

Canine cancer vaccine shows early promise, http://www.news.wisc.edu/12063 University of Wisconsin-Madison, Jan., 2006