Pet Columns, Office of Public Engagement, College of Veterinary Medicine at the University of Illinois at Urbana-Champaign

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Tumors: Take a Closer Look At Lumps and Bumps


Pet Column for the week of July 21, 2003


Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Ann Marie Falk
Information Specialist

Odds are during your daily scratching and petting session with your pooch there will come a time when you find a lump or bump. Don't panic! Fido isn't dying, but he does need to take a trip to the veterinarian.

As they age, dogs and cats-like people-will develop warts and masses. The most common time of life for tumors to begin to form is middle age, around 5 years and older. Not all tumors mean your pet has cancer.

"Any animal, from the very young to the very old, can develop a skin or subcutaneous (just below the skin) growth. The majority of tumors are benign. Sometimes benign tumors need to be removed because they impinge on surrounding structures, thereby causing problems. Also, if they might break open and cause infection, they need to be removed," says Dr. Sarah Charney, a veterinary oncologist formerly at the University of Illinois Veterinary Teaching Hospital in Urbana.

If you find a mass (growth) on your pet, ask your veterinarian examine it. Your veterinarian will aspirate the mass, which means using a needle to collect a sample of the cells inside. Your veterinarian will look at these cells under a microscope to determine what kind of tumor it is and if it is malignant or benign. Cats are less prone than dogs are to developing skin and subcutaneous tumors, but both types of pets will need veterinary care for a growth.

Benign tumors do not spread to other organs or tissues. They can, though, grow in size. Benign tumors do not need to be removed unless they are crowding another structure. A benign tumor that is growing near the eye will probably need to be removed. Some owners opt to remove benign tumors for cosmetic reasons. Dogs like to look their best too!

"Many dogs get lipomas as they age. A lipoma is a fatty tumor that feels like a soft mass. It is common in older animals. When we aspirate it, we just see fat. No treatment is necessary unless it is causing problems for neighboring areas," comments Dr. Charney.

Unfortunately some tumors are malignant, i.e., cancerous. If your veterinarian thinks a mass may be malignant, more diagnostic tests need to be done. These tumors can and usually do spread to other organs, causing problems throughout the body. Where a tumor will spread depends on the type of tumor.

"Treatment for malignant tumors is usually surgical removal followed by either chemotherapy or radiation. Radiation therapy is recommended when not all of the tumor can be removed surgically. Chemotherapy is used when there is a high risk that the tumor will spread to other parts of the body. The chemotherapy drugs used are administered either orally or intravenously. Animals are treated with the same medications used in human cancer treatment," states Dr. Charney.

In cats, tumors can grow at the site of a recent injection. After your annual vaccination visit, watch the injection area to see if bumps develop. If the lump is bigger than 2 cm or persists for longer than 30 days, head back to the veterinarian�s office.

This reaction to vaccines occurs in a very small number of animals. Cats are more prone than dogs to have a bump at a vaccination site. This doesn't mean you should not vaccinate; just be aware that there is a small chance a tumor will form. Skipping vaccinations is asking for trouble!

Contact your local veterinarian if you find a mass on your pet or have any questions relating to tumor growth or cancer therapy.