The thought of cancer strikes fear into the heart of many pet owners, and with good reason: About 20% to 25% of dogs and cats will develop cancer during their lives, and the risk increases as pets age.
But the good news is that many pets do well with chemotherapy and other treatments, and even pets with aggressive cancers may experience long remissions (periods during which cancer is not detectable). In some cases, surgery can provide a cure—especially if the cancer is caught early and hasn’t spread.
Understanding the types of cancer pets can get, as well as the signs of cancer to watch for in cats and dogs, is important in helping to provide pets with the best quality of life for as long as possible.
What Types of Cancer Do Pets Get?
As in people, dogs and cats can develop many different types of cancer. Cancer develops when the DNA in cells become damaged and the resulting abnormal cells begin to duplicate (make copies of themselves) and multiply uncontrollably. These cells generally form tumours (lumps or growths) that can destroy and spread into surrounding tissue, or the damaged cells are released into the blood and circulate to other areas of the body (metastasize).
This process can occur in any part of the body, but certain kinds of cancer are more common in pets, including:
Fibrosarcoma—This type of soft-tissue cancer usually forms beneath the skin and in the connective tissue of the skin, often on the legs and trunk, but can also develop in the nose and mouth (and sometimes in the jawbone).
Lymphoma—Affecting the lymph nodes and lymphatic system (which includes the spleen and tonsils), this form of cancer can stay localized (in one specific area, such as under the jaw or behind the knees) or can spread throughout the body. Lymphoma can develop in dogs and cats and is associated with the feline leukaemia virus (FeLV) in cats.
Hemangiosarcoma—Developing from cells that line the blood vessels, this type of cancer often attacks the spleen but can also affect the heart, liver, and skin.
Mammary (breast) cancer—These tumours usually begin as tiny nodules near a nipple. Mammary gland carcinomas tend to develop in unspayed female dogs and cats. Male pets rarely develop this cancer, although it is possible.
Mast cell tumours—This kind of cancer tends to form masses or nodules in the skin, but it can also affect other areas, such as the liver, intestine, bone marrow, or spleen.
Melanoma—A common oral cancer in dogs that tends to affect breeds with dark gums and tongues, melanoma can be difficult to notice in the early stages and unfortunately tends to spread quickly throughout the body. Melanoma is rare in cats.
Oral squamous cell carcinoma—The most common oral cancer in cats, squamous cell carcinoma can develop in the gums, tongue, roof of the mouth, or tonsils and can also grow into the jawbone.
Osteosarcoma—This painful type of bone cancer commonly affects the long bones in the legs. These malignant tumours can also develop in the jaw, ribs, backbone, and pelvis, as well as in areas that aren’t bone, such as the kidneys, liver, mammary glands, and spleen.
Many pets respond well to chemotherapy and other cancer treatments.
What Are Symptoms of Cancer in Pets?
The signs of cancer vary depending on the type of cancer, and many cancers are silent (don’t have any obvious signs) in the early stages. But generally, pets with cancer may have:
- A lump that continues to grow (either slowly or quickly) or fluctuates in size
- A lump, sore, or lesion that bleeds or doesn’t heal
- Abnormal bleeding
- Bad breath, drooling, or difficulty eating
- Changes to the eye (such as the iris darkening)
- Facial swelling
- Loss of energy
- Loss of or decreased appetite
- Pale gums
- Swollen lymph nodes
- Trouble breathing
- Trouble urinating or defecating
- Unexplained diarrhea or vomiting
- Unexplained weight loss or loss of muscle mass
Many of the symptoms listed can also be signs of other conditions or diseases, so don’t panic if your pet shows any of them, but also don’t delay in letting us know about them. The sooner we catch cancer or other medical problems, the better the chance of a positive outcome for your pet.
Can I Prevent Cancer in My Pet?
Unfortunately in most cases, there’s not much you can do to try to keep your pet from developing cancer.
Many factors are involved in cancer development, including exposure to known carcinogens (cancer-causing agents) such as cigarette smoke, chemicals, and sunlight.
Some cancers may be related to obesity, inflammation, and infection, while others can be linked to specific hormones.
Certain breeds may be genetically predisposed to developing cancer, and the risk of dogs and cats developing cancer increases with age.
Experts don’t know why certain factors promote the growth of cancer in some pets but not in others.
Spaying or neutering your pet can help eliminate or reduce the risk of several types of cancer, including mammary gland, ovarian, prostate, testicular, and uterine cancer. Obesity is believed to play a role in the development of cancer, so keeping your pet at a healthy weight may help reduce the risk of certain cancers.
Most cancers can’t be transmitted to other pets. However, if one of your pets has a condition that is transmissible to other cats and can cause cancers, such as FeLV, you will want to take precautions to ensure that other cats in your household don’t become infected. You can ask us for advice.
How We Can Help Pets With Cancer
At Tej Dhaliwal Veterinary Group, we have many options to help treat cancer in dogs and cats, including surgery, chemotherapy, and radiation therapy. Let us know right away if you’ve noticed any symptoms of cancer or changes in your pet’s behaviour, or if your pet just seems off.
How early cancer is diagnosed and how quickly treatment is started may make a difference in a pet’s outcome. If you have any questions or concerns, please give us a call.
- American Animal Hospital Association (AAHA). Is my dog at risk for cancer? https://www.aaha.org/your-pet/pet-owner-education/ask-aaha/canine-cancer
- American Veterinary Medical Association (AVMA). Cancer in pets. https://www.avma.org/resources/pet-owners/petcare/cancer-pets
- American College of Veterinary Surgeons (ACVS). Bone tumors in cats and dogs. https://www.acvs.org/small-animal/bone-tumors
- ACVS. Mast cell tumors. https://www.acvs.org/small-animal/mast-cell-tumors
- Canadian Cancer Society. How cancer starts, grows and spreads. https://www.cancer.ca/en/cancer-information/cancer-101/what-is-cancer/how-cancer-starts-grows-and-spreads
- Colorado State University Flint Animal Cancer Center. Common cancers in cats. https://www.csuanimalcancercenter.org/2019/11/20/common-cancers-in-cats
- Cornell University College of Veterinary medicine. Feline leukemia virus. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-leukemia-virus
- International Cat Care. Cancer in cats. https://icatcare.org/advice/cancer-in-cats
- NC State Veterinary Hospital. Medical oncology: feline oral squamous cell carcinoma. https://cvm.ncsu.edu/nc-state-vet-hospital/small-animal/oncology/feline-oral-squamous-cell-carcinoma
- Washington State University Veterinary Teaching Hospital Oncology Service. Canine mast cell tumors. https://vth.vetmed.wsu.edu/specialties/oncology/information-for-owners/mast-cell-cancer
All accessed November 11, 2020.