Signs and Symptoms of Cancer in Pets

Author: Christina Bach, LCSW, MBE, OSW-C, FAOSW
Content Contributor: Hannah Nibauer, MSW
Last Reviewed: June 05, 2022

Since our pets cannot tell us when they’re in pain, we need to be aware of behavioral changes that may signal our pet isn't feeling well. Behavior changes can include

  • Changes in eating or less interest in food.
  • Changes in bowel/bladder habits.
  • Changes in activity level.
  • Drinking more or less water.
  • Changes in behavior--new aggression, anxiety, wanting to be around or handled by people/other pets less, or even destructive behaviors.

It is important to talk to your veterinarian about any of these changes as they could be signs of something medical happening with your pet. Not all abnormalities or changes mean cancer! But, as in humans, early detection of cancer in pets is critical to ensuring the best possible treatment outcomes. Successful treatment often hinges on our ability to "catch it early".

Besides behavior changes, there are symptoms of cancer in animals that are similar to those in humans. Some of the most common early warning signs of cancer in pets are:

  • Abnormal swelling that persists or continues to grow: Regularly check your pet's skin for lumps and bumps. Check behind the ears, in the mouth, and around the face. Cancer can move fast. If you find any abnormality, be sure to note it and measure it. If it changes shape and size, it's time to see the vet for the growth to be evaluated.
  • Sores that do not heal: If your pet has a sore on the skin that is not going away or healing, it’s time to call the veterinarian.
  • Unexplained weight loss: Unless there has been a diet restriction or change, weight should remain stable throughout your pet’s life.
  • Loss of appetite: There are many reasons why your pet may have a loss in appetite, cancer being one of them. Seek veterinary advice if this is the case.
  • Pale gums: Healthy gums are a red-pink color. Pale or grey gums can be a sign of illness. If you notice your pet has pale, almost white, gums, seek veterinary assistance as soon as possible.
  • Bleeding or discharge from any body opening such as the nose or mouth.
  • Bad odor, especially from the mouth.
  • Difficulty eating or swallowing.
  • Reluctance to exercise or loss of stamina.
  • Persistent lameness or stiffness.
  • Difficulty breathing

Cancer presents itself in our pets in subtle ways. We know our pets better than anyone. It's important to report changes to your veterinarian. Just because your pet has some symptoms or is acting differently, doesn’t mean that it is cancer. Being aware and mindful of your pet’s health and well-being is an important step in the early detection and treatment of cancer.


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