What Are the Signs of Cancer in Pets

People are warned about the dangers and warning signs of cancer on a regular basis, but many may fail to realize similar risks exist for their animal companions.

Owners need to be aware of the possibility that their dog or cat could develop cancer so they are tuned in to warning signs and know there is treatment available, said Ruthanne Chun, doctor of veterinary medicine and animal cancer specialist at Kansas State University .

Chun said the best way to detect a cancerous tumor is not an unpleasant task at all. “I usually tell people the best way to detect a tumor is just to pet their dog or cat a lot,” Chun said. “If you happen to feel an abnormal bump or lump, or if the animal seems tender where they didn’t used to be, then you ought to have it looked at.

“There are lots of tumors that are benign, meaning they’re not likely to spread to other parts of the body or cause the animal’s death. Just because there’s a bump doesn’t mean it’s bad, but it isn’t necessarily good either. I always encourage people to get it checked out by their veterinarian.”

Other physical signs may include a decrease in appetite, vomiting or being less active, Chun said. In addition, any signs of lameness may be an indication of bone cancer.

The feline leukemia virus (or FeLV) and the feline immunodeficiency virus (or FIV) are two diseases that effect a cat’s immune system, which often makes the cat more susceptible to developing cancerous tumors. Cats can be vaccinated against FeLV, but there is no vaccination against FIV.

Mammary, or breast cancer, is a common cancer in dogs and cats. Getting a dog spayed before she has completed two heat cycles greatly reduces her chance of getting breast cancer, and having a cat spayed reduces her risk of breast cancer slightly, Chun said.

Chun said spaying an animal and vaccinating for FeLV are known to help reduce the risk of breast cancer and other tumor types, but early detection is the best that can be hoped for with many cancers. Skin tumors, lymphoma (a cancer of the lymph nodes) and osteosarcoma (bone cancer) are unpreventable cancers Chun said she sees frequently in dogs and cats.

“Most of the cancer we see in animals is for unknown reasons,” Chun said. “Herbicides are suspected as a cause of cancer. Use of weed control products greater than label recommendations probably isn’t good for the animal or owner. Cigarette smoke has also been a big issue with people, but it hasn’t been shown to be as much of a problem for animals. I’d still recommend avoiding exposing your animal to it.”

When a dog develops a cancerous tumor, the treatment options are similar to those available to humans. Chemotherapy, radiation therapy or surgery are offered, depending on the type of cancer. Immunotherapy (drug therapy that stimulates the immune system) may also be an option.

Chun said many people have misconceptions about treating their animal with chemotherapy, feeling that it would be unethical or mean. “Dogs and cats are much more tolerant than people of chemotherapy,” Chun said. “They can tolerate the same drugs without getting as sick as people. The treatments also tend to be less aggressive because we don’t treat them with the same doses of chemotherapy that would be given to a person.

“They don’t end up spending days in the hospital, not being able to be at home with their owners. We still watch for toxicities, but overall their quality of life is good to excellent. They tend to feel good and still want to play and go for walks and eat normal food and everything.”

Chun said treatment for a 30-pound dog with a common tumor, like lymphoma, would be $800 to $1,000 for a six-month treatment. This would prolong the dog or cat’s life for an average of one year. Chun said it is always important to think in animal years, not people years. She said one year is a long time to a dog or cat.

Chun said it is also important to recognize that animals can benefit from treatment even if they are older. “I hate to tell people whether or not to treat an animal as it should be the owner’s decision,” Chun said. “However, I do tell them that age is not a disease. All else being equal, if the animal is feeling good to begin with and she’s been eating and going for her walks and doing everything normal before you notice this lump, then yes, you should take proper steps in addressing the disease. But if she has kidney failure and heart failure or a lot of other problems, the treatment may be a lot harder on her — it depends on the overall health status of the animal, but not the age.”

For more information, contact Chun at (785) 532-5690 .

Prepared by Bree Bisnette. Kansas State University News Services, 9 Anderson Hall, Manhattan KS

NB: Pet Plan Insurance reports that 60% of dogs over age six will develop cancer. My clinical experience verifies this distressing number.-Dr. Jeff

Please note: The information provided here is intended to supplement the recommendations of your veterinarian. Do not disregard veterinary advice or delay treatment based on information on this site. Nothing can replace a complete history and physical examination performed by your veterinarian. -Dr. Jeff