Advances in early recognition, diagnosis, and treatment are improving cancer treatment success rates for pets.  

One in every four dogs will develop cancer in their lifetime, and this increases to 50 percent in dogs over 10 years of age, according to the American Veterinary Medical Association. For cats, the risk of cancer varies between 25 to 35 percent. Since November is Pet Cancer Awareness Month, veterinary oncologists, Drs. Joshua L. Lachowicz and John Farrelly of BluePearl Specialty and Emergency Pet Hospital, are educating pet owners on the early signs of cancer, as well as treatment options and possible ways to prevent cancer in furry companions.

Overall, lymphoma is the most common cancer in both dogs and cats. After lymphoma, there are some tumors that are more common in dogs versus cats, and vice-versa,” explained Dr. John Farrelly, MS, DACVIM (Oncology), DACVR (Radiology), BluePearl in Midtown Manhattan.

“Some breeds are prone to develop certain tumors. For example, Scottish terriers are more likely to develop bladder tumors, brachiocephalic breeds, like bulldogs, are more prone to developing certain brain tumors. This is not a reason to avoid these breeds. However, if you have a purebred dog it is a good idea to know what types of cancer they may be prone to develop, so you can be on the lookout for early warning signs of these tumor types.”

Signs and symptoms.

Pet owners should examine their pets for any lumps or bumps, says Dr. Farrelly. At home, continually monitor pets for abnormalities, including lameness, discomfort, changes in body composition and/or symmetry, attitude and behavior. You can also feel for lumps and bumps or unusual swellings on the pet’s body. Be sure check everywhere, including the neck, paws, belly/mammary region, and even the mouth if permitted.

Although the average age of cancer onset depends on the type of cancer, most cancers occur in middle age to older pets. In general, if your older pet develops any abnormality, it is best to have them seen by a veterinarian. Also, even if your pet is acting normally, it is best to get them in to their primary care veterinarian. Dr. Farrelly says primary care veterinarians are the first line of defense in finding tumors, and the best chance to cure or control tumors is to diagnose them early and have them treated right away.

Common warning signs of cancer in cats and dogs.

  • Persistent or abnormal swelling including palpable lumps/bumps
  • Sores that do not heal
  • Loss of weight and/or loss of appetite
  • Bleeding or abnormal discharge from any body opening
  • Difficulty eating or swallowing
  • Lethargy or loss of stamina
  • Persistent lameness or stiffness
  • Difficulty urinating, defecating, or breathing


Treatment for cancer in pets varies depending on the type of cancer, stage and grade, as well as considerations for the pet. In dogs, lymphoma, various skin tumors (mast cell tumors and sarcomas), osteosarcoma, melanoma, hemangiosarcoma, and transitional cell carcinoma are the most common. In cats, lymphoma is the most commonly diagnosed type of cancer.

It is not uncommon for tumors to require a multimodality approach, which includes some combination of surgery and/or radiation and/or chemotherapy.

Some cancers, such as lymphoma, may only need to be treated with chemotherapy, while others, such as a skin tumor, may only require surgical removal. Nasal tumors or some brain tumors are often successfully treated with radiation alone,” remarked Dr. Joshua L. Lachowicz, DACVIM (Oncology), Regional Vice President of Medicine, Northeast, BluePearl.

“Radiation therapy is used following surgery for incompletely excised tumors but may also be used as a primary means of treatment depending on the type of cancer.”

Immunotherapy—enhancing the pet's ability to generate antibodies against cancer cells or improving the immune cells' ability to detect tumors—may be used in certain circumstances, says Dr. Lachowicz. It is also important to keep in mind that with chemotherapy, treatment involves visits once every one to three weeks for outpatient therapy.


While there is very limited information regarding the prevention of cancer in pets, Dr. Farrelly says the best approach to pet cancer prevention is to provide pets with a healthy lifestyle, including a nutritionally balanced diet and keeping up with preventative care.

Additionally, Dr. Lachowicz offers a few proactive measures owners can take to help reduce the risk of pet cancer:

  • Keep your pet at a healthy weight and provide nutrient-dense food that includes all the essential minerals and vitamins that a cat or dog’s body needs to stay healthy, strong and energetic.
  • Spay or neuter your pet at an appropriate age as directed by a veterinarian.
  • Minimize exposure to carcinogens and other toxins. This includes secondhand smoke, pesticides and herbicides, which have been associated with increased risks of some cancers. Carcinogens in cigarette smoke can be deposited on a dog or cat’s fur. When they groom or lick themselves or another animal, they unintentionally ingest these carcinogens, which can cause oral tumor development.
  • Obtain yearly physical examinations. Pets, especially geriatric ones, should receive annual checkups from a veterinarian. Exams that include blood and urine tests can lead to early detection of cancer—even if the dog or cat may not show physical or behavioral symptoms of illness. If cancer is caught early, treatment is less aggressive and more likely to result in remission or a cure.

Take things one step at a time & get informed.

For pet owners concerned about pet cancer, BluePearl oncologists suggest bringing the pet in for a consultation with a primary care veterinarian and/or an oncologist and/or radiation oncologist. Learn about treatment options, potential side effects of treatment, prognosis, and cost. Once you have all of the information you need, along with the results of the initial staging tests, then you can proceed to make an informed decision about the best treatment option for your pet and family. If the pet’s quality of life is not improved and/or maintained, treatment can be modified or discontinued.

Learn more about veterinary oncology at BluePearl:

Play Youtube Video