Pet Cancer Warning Signs

Pet Cancer Warning Signs

Early detection is key, know the signs of pet cancer

Content courtesy of One Cure Staff Writer, Colorado State University / Flint Animal Cancer Center

Content courtesy of One Cure Staff Writer, Colorado State University / Flint Animal Cancer Center 

November is National Pet Cancer Awareness Month. Each year, more than six million dogs and cats are diagnosed with cancer. Cancer is the leading cause of death in pets beyond middle age. Knowing what to look for can help with early detection. As with people, early detection can make a difference. Following are the top 10 warning signs of cancer in companion animals. If you notice any of these signs in your pet, please consult a veterinarian.

  1. Abnormal swellings that persist and continue to grow

    Pet your pet! This is the best way to find lumps, bumps, or swellings that could be anywhere on the body. 

  2. Sores that do not heal

    Non-healing sores can be a sign of infection or cancer. Your veterinarian can determine the reason why the sore is not healing.

  3. Weight loss

    If your pet is not on a diet, but is losing weight, illness could be to blame. 

  4. Loss of appetite

    It is not normal for pets to lose their appetite. This may be a sign of illness. 

  5. Bleeding or discharge

    Bleeding can occur for many reasons - most of which are abnormal. Note that vomiting and diarrhea are examples of abnormal discharge. 

  6. Offensive odor

    This is a common sign especially for tumors in the mouth, nose or anus. 

  7. Difficulty eating or swallowing

    This is a common sign of cancers of the mouth and neck.

  8. Hesitation to exercise or loss of stamina

    This can be one of the first signs that your pet is not feeling well.

  9. Persistent lameness

    There are many causes of lameness, including nerve, muscle or bone cancer. 

  10. Difficulty breathing, urinating, or defecating

    These problems are likely caused by an underlying health problem. 

Schedule a veterinary appointment if your pet displays any of these symptoms. Early detection and treatment are important for pets, just as for people.

About One Cure Cancer is cancer. Colorado State University’s One Cure program is founded on the principle that cancer affects all creatures and, that treatment breakthroughs come through collaboration between scientists and doctors who are working with both people and animals. This approach is known as comparative or translational oncology; the study of cancer in people and pets to benefit both species. It is the core of One Cure and is a guiding concept for the Flint Animal Cancer Center at Colorado State University. The center works to improve the prevention, diagnosis, and treatment of cancer in pet animals and, by working with the human medical field, translates research findings and knowledge to also help people with cancer. For more information, visit

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